WO2010136431A9 - Spiro epoxides as intermediates - Google Patents

Spiro epoxides as intermediates Download PDF

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Publication number
WO2010136431A9
WO2010136431A9 PCT/EP2010/057121 EP2010057121W WO2010136431A9 WO 2010136431 A9 WO2010136431 A9 WO 2010136431A9 EP 2010057121 W EP2010057121 W EP 2010057121W WO 2010136431 A9 WO2010136431 A9 WO 2010136431A9
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Prior art keywords
alkyl
substituted
haloalkyl
halogen
crc
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PCT/EP2010/057121
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French (fr)
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WO2010136431A1 (en
Inventor
James Nicholas Scutt
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Syngenta Limited
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Priority claimed from GB0909303A external-priority patent/GB0909303D0/en
Priority claimed from GB0921345A external-priority patent/GB0921345D0/en
Priority to EA201101675A priority Critical patent/EA020243B1/en
Priority to CA2763830A priority patent/CA2763830A1/en
Priority to US13/375,223 priority patent/US8680299B2/en
Priority to AU2010252000A priority patent/AU2010252000B2/en
Priority to JP2012512334A priority patent/JP5735491B2/en
Priority to EP10720780A priority patent/EP2435415A1/en
Application filed by Syngenta Limited filed Critical Syngenta Limited
Priority to BRPI1014691-1A priority patent/BRPI1014691A2/en
Priority to AP2011006038A priority patent/AP2011006038A0/en
Priority to MX2011012533A priority patent/MX2011012533A/en
Priority to CN201080023447.0A priority patent/CN102448948B/en
Priority to UAA201115171A priority patent/UA106494C2/en
Publication of WO2010136431A1 publication Critical patent/WO2010136431A1/en
Publication of WO2010136431A9 publication Critical patent/WO2010136431A9/en
Priority to IL216364A priority patent/IL216364A0/en
Priority to US14/157,685 priority patent/US8987476B2/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D493/00—Heterocyclic compounds containing oxygen atoms as the only ring hetero atoms in the condensed system
    • C07D493/02—Heterocyclic compounds containing oxygen atoms as the only ring hetero atoms in the condensed system in which the condensed system contains two hetero rings
    • C07D493/10—Spiro-condensed systems
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N43/00—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds
    • A01N43/02—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one or more oxygen or sulfur atoms as the only ring hetero atoms
    • A01N43/04—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one or more oxygen or sulfur atoms as the only ring hetero atoms with one hetero atom
    • A01N43/14—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one or more oxygen or sulfur atoms as the only ring hetero atoms with one hetero atom six-membered rings
    • A01N43/16—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with one or more oxygen or sulfur atoms as the only ring hetero atoms with one hetero atom six-membered rings with oxygen as the ring hetero atom
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D309/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings
    • C07D309/02—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
    • C07D309/08—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D309/10—Oxygen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D309/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings
    • C07D309/16—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
    • C07D309/28—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D309/30—Oxygen atoms, e.g. delta-lactones
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D309/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings
    • C07D309/32—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members

Definitions

  • the present invention relates to novel compounds, their preparation and their use as intermediates in the preparation of herbicidally active substituted 4-phenyl-3,5-pyrandiones, 4-phenyl-3,5-thiopyrandiones and 6-phenylcyclohexane-1 ,3,5-triones.
  • the present invention accordingly relates to compounds of formula I
  • R 1 is halogen, CrC 4 alkyl, Ci-C 4 haloalkyl, C 3 -C 6 cycloalkyl, Ci-C 4 alkoxy, Ci-C 4 haloalkoxy, d- C 4 alkylthio, CrC 4 alkylsulfinyl, Ci-C 4 alkylsulfonyl;
  • R 2 is hydrogen, halogen, methylsulfonyloxy, Ci-C 4 haloalkylsulfonyloxy, p-tolylsulfonyloxy, optionally substituted aryl or optionally substituted heteroaryl;
  • r is 0, 1 , 2 or 3;
  • R 3 if r is 1 is C C 6 alkyl, C C 6 haloalkyl, C C 6 alkoxy, C C 6 haloalkoxy, C C 6 alkylthio, C C 6 alkylsulfinyl, CrC 6 alkylsulfonyl, cyano or nitro; or the substituents R 3 , if r is 2 or 3, independently of each other, are CrC 6 alkyl, CrC 6 haloalkyl, CrC 6 alkoxy, CrC 6 haloalkoxy, CrC 6 alkylthio, CrC 6 alkylsulfinyl, CrC 6 alkylsulfonyl, cyano or nitro;
  • Y is O, S, SO, S0 2 or CO;
  • R 4 , R 5 , R 6 and R 7 are hydrogen, Ci-C 4 alkyl, Ci-C 4 haloalkyl, d- C 4 alkoxyCi-C 4 alkyl, Ci-C 4 alkylthioCi-C 4 alkyl, Ci-C 4 alkylsulfinylCi-C 4 alkyl, d- C 4 alkylsulfonylCi-C 4 alkyl, cyclopropyl or cyclopropyl substituted by d- or C 2 alkyl, d- or C 2 haloalkyl or halogen; cyclobutyl or cyclobutyl substituted by d- or C 2 alkyl; oxetanyl or oxetanyl substituted by d- or C 2 alkyl; C 5 -C 7 cycloalkyl or C 5 -C 7 cycloalkyl substituted by d- or C 2 alkyl;
  • R 4 and R 5 , or R 6 and R 7 are joined to form a 5-7 membered saturated or unsaturated ring in which a methylene group is optionally replaced by an oxygen or sulfur atom, or a 5-7 membered saturated or unsaturated ring substituted by d- or C 2 alkyl, where a methylene group of the ring is optionally replaced by an oxygen or sulfur atom; or
  • R 4 and R 7 are joined to form a 5-7 membered saturated or unsaturated ring unsubstituted or substituted by d- or C 2 alkyl, d- or C 2 alkoxy, d-or C 2 alkoxyd- or C 2 alkyl, hydroxy, halogen, phenyl or phenyl substituted by d-C 4 alkyl, d-C 4 alkoxy, d-C 4 haloalkyl, halogen, nitro, cyano, d-dalkylthio, d-C 4 alkylsulfinyl, d-C 4 alkylsulfonyl or d-C 4 alkylcarbonyl; heteroaryl or heteroaryl substituted by d-C 4 alkyl, d-C 4 alkoxy, d-C 4 haloalkyl, halogen, nitro, cyano, d-dalkylthio, d-C 4 alkylsul
  • the invention further relates to a process for the preparation of 4-phenyl-3,5-pyrandiones, 4- phenyl-3,5-thiopyrandiones and 6-phenylcyclohexane-1 ,3,5-triones of formula (A) which is shown below, using the compounds of the formula I as intermediates.
  • the alkyl substituents and (halo)alkyl moieties of alkoxy, alkylthio etc. having 1 to 6 carbon atoms are preferably methyl, ethyl, propyl, butyl, pentyl and hexyl, in the form of their straight and branched isomers.
  • Suitable cycloalkyl groups contain 3 to 7 carbon atoms and are for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. Cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl are preferred.
  • Suitable cycloalkene groups contain 4 to 7 carbon atoms and may contain up to 3 double bonds.
  • Preferred halogens are fluorine, chlorine and bromine.
  • Preferred examples of aryls are phenyl and naphthyl.
  • Preferred examples of heteroaryls are thienyl, furyl, pyrrolyl, isoxazolyl, oxazolyl, oxetanyl, isothiazolyl, thiazolyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyrazinyl, triazinyl, oxadiazolyl, thiadiazolyl and pyridazinyl, and, where appropriate, N-oxides and salts thereof.
  • aryls and heteroaryls can be substituted by one or more substituents, where preferred substituents are halogen, CrC 4 alkyl, Ci-C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 -C 4 haloalkenyl, C 2 -C 4 alkynyl, d- C 4 alkoxy, CrC 4 haloalkoxy, CrC 4 alkylthio, CrC 4 alkylsulfinyl, CrC 4 alkylsulfonyl, d- C 4 haloalkylthio, CrC 4 haloalkylsulfinyl, CrC 4 haloalkylsulfonyl, nitro or cyano.
  • substituents are halogen, CrC 4 alkyl, Ci-C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 -C 4 haloalkenyl, C 2 -C 4 alky
  • R 1 is halogen, Ci-C 4 alkyl, Ci-C 4 haloalkyl, C 3 - C 6 cycloalkyl or Ci-C 4 -haloalkoxy.
  • R 2 is halogen, aryl or heteroaryl; or aryl or heteroaryl both substituted by halogen, Ci-C 4 alkyl, Ci-C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 - C 4 haloalkenyl, C 2 -C 4 alkynyl, Ci-C 4 alkoxy, Ci-C 4 haloalkoxy, phenoxy, Ci-C 4 alkylthio, C C 4 alkylsulfinyl, CrC 4 alkylsulfonyl, Ci-C 4 haloalkylthio, CrC 4 haloalkylsulfinyl, d- C 4 haloalkylsulfonyl, C 3 -C 6 cycloalkyl, CrC 4 alkylsulfonyloxy, CrC 4 haloalkylsulfonyloxy, d- dalkoxy
  • R 2 in the compounds of formula I is halogen, aryl or heteroaryl; or aryl or heteroaryl both substituted by halogen, CrC 4 alkyl, CrC 4 haloalkyl, phenoxy, C 2 -C 4 alkenyl, C 2 -C 4 haloalkenyl, C 2 -C 4 alkynyl, CrC 4 alkoxy, CrC 4 haloalkoxy, CrC 4 alkylthio, C C 4 alkylsulfinyl, CrC 4 alkylsulfonyl, CrC 4 haloalkylthio, CrC 4 haloalkylsulfinyl, d- C 4 haloalkylsulfonyl, nitro or cyano.
  • R 2 is phenyl, thienyl, furyl, pyrrolyl, isoxazolyl, oxazolyl, isothiazolyl, thiazolyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyrazinyl, triazinyl, pyridazinyl, oxadiazolyl and thiadiazolyl, and N-oxides and salts thereof, where these rings are unsubstituted or substituted by halogen, CrC 4 alkyl, CrC 4 haloalkyl, C 2 -C 4 alkenyl, C 2 - C 4 haloalkenyl, C 2 -C 4 alkynyl, CrC 4 alkoxy, CrC 4 haloalkoxy, CrC 4 alkylthio, CrC 4 alkylsulfinyl, CrC 4
  • R 2 is phenyl or pyridyl or phenyl or pyridyl both substituted by halogen, nitro, cyano, Ci-C 2 alkyl, Ci-C 2 haloalkyl, Ci-C 2 alkoxy or CrC 2 haloalkoxy.
  • R 2 is phenyl substituted at the para-position by halogen (in particular chlorine) and is optionally further substituted by halogen, nitro, C C 2 alkyl, Ci-C 2 haloalkyl, Ci-C 2 alkoxy or Ci-C 2 haloalkoxy.
  • halogen in particular chlorine
  • R 3 is hydrogen (r is 0) or CrC 6 alkyl, especially hydrogen.
  • R 3 if r is 1 , is C C 3 alkyl.
  • R 4 , R 5 , R 6 and R 7 independently of each other, are hydrogen, CrC 4 alkyl, Ci-C 4 haloalkyl, Ci-C 4 alkoxyCrC 4 alkyl, d- C 4 alkylthioC C 4 alkyl, C 1 -C 4 alkylsulfinylC 1 -C 4 alkyl, Ci-C 4 alkylsulfonylC C 4 alkyl; C 5 - C 7 cycloalkyl or C 5 -C 7 cycloalkyl substituted by C or C 2 alkyl or d- or C 2 haloalkyl and in which a methylene group is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; C 5 -C 7 cycloalkylC
  • R 4 , R 5 , R 6 and R 7 independently of each other, are hydrogen, Ci-C 2 alkyl, CrC 2 haloalkyl or Ci-C 2 alkoxyCrC 2 alkyl.
  • R 1 is ethyl, methyl or cyclopropyl
  • R 2 is phenyl or phenyl substituted by halogen or Ci-C 2 alkyl
  • R 3 is hydrogen
  • R 4 , R 5 , R 6 and R 7 , independently of each other, are CrC 2 alkyl.
  • Ri is methyl, ethyl, cyclopropyl, n-propyl, halogen, trifluoromethoxy, difluoromethoxy and trifluoromethyl
  • R 4 , R 5 , R 6 and R 7 independently of each other, are hydrogen, methyl and ethyl
  • R 2 is halogen, phenyl substituted by halogen, Ci-C 4 alkyl, Ci-C 4 haloalkyl, Ci-C 4 haloalkoxy or Ci-C 4 alkoxy
  • R 3 is hydrogen and Y is oxygen
  • Ri is ethyl or cyclopropyl
  • R 4 , R 5 , R6 and R 7 are methyl
  • R 2 is phenyl substituted once or twice by fluorine, chlorine, methoxy or methyl
  • R 3 is hydrogen and Y is oxygen
  • Ri is ethyl
  • R 4 , R 5 , R 6 and R 7 are methyl
  • R 2 is 4-chlorophenyl, 2,4- dichlorophenyl and 2-fluoro-4-chlorophenyl
  • R 3 is hydrogen and Y is oxygen.
  • Ri is ethyl, trifluoromethyl, cyclopropyl, difluoromethoxy, trifluoromethoxy , fluoro, bromine or iodine
  • R 4 , R 5 , R 6 and R 7 independently of each other, are hydrogen or methyl
  • R 2 is bromine
  • R 3 is hydrogen and Y is O, where
  • Ri is ethyl, cyclopropyl
  • R 4 , R 5 , R6 and R 7 are methyl
  • R 2 is bromine
  • R 3 is H
  • Y is O.
  • Suitable acids include Bronsted acids such as mineral acids and organic acids, for example sulfuric acid, hydrochloric acid, hydrogen chloride, p-toluenesulfonic acid, acetic acid and formic acid, and Lewis acids such as metal halides, for example boron trifluoride, aluminium chloride, iron chloride, tin(IV) chloride, zinc chloride, zinc bromide, lithium perchlorate, as well as metal triflates such as scandium triflate and ytterbium triflate. Mixtures of such acids can also be used.
  • the conversion of a compound of formula (I) into a compound of formula (A) may be considered to be an example of a semi-Pinacol rearrangement (see for example M.
  • Suitable solvents are those chosen to be compatible with the acid used, and include chlorinated hydrocarbons, alcohols, ethers, aromatics and organic acids, for example dichloromethane, dichloroethane, diethyl ether, acetic acid, formic acid, toluene, benzene, methanol, ethanol, isopropanol and tetrahydrofuran. Mixtures of solvents can also be used.
  • the reaction is performed using concentrated sulphuric acid in dichloroethane.
  • the preferred reaction temperature is within the range of between -50°C and 83°C, even more preferably between -50°C and 40°C.
  • Additional preferred reaction conditions are the use of lithium perchlorate solution in ether in combination with 0.1 - 100mol% ytterbium triflate as acid, at a temperature range between 0°C and 60°C.
  • the present preparation process is therefore suitable especially for the cost-effective, large- scale preparation of the diones and triones of formula (A).
  • Epoxidation may be effected by treatment of a compound of formula (B) with a suitable oxidising agent such as an organic peroxide or metal hyperchlorite, for example dimethyldioxirane, sodium hypochlorite, hydrogen peroxide, tert-butyl peroxide or trifluoroperacetic acid, optionally in combination with a suitable base (such as an alkali metal hydroxide or carbonate, alkaline earth metal hydroxide or carbonate, or an amine base such as 1 ,8-diazabicyclo[5.4.0]-undec-7-ene), optionally in a suitable solvent (such as an alcohol, a halogenated hydrocarbon or an aromatic compound, for example methanol, ethanol, dichloromethane or toluene) and at a suitable temperature.
  • a suitable oxidising agent such as an organic peroxide or metal hyperchlorite, for example dimethyldioxirane, sodium hypochlorite, hydrogen peroxide, tert-
  • the reaction can also be performed under biphasic conditions, in which a phase-transfer reagent is also typically used in 0.001 -50 mol%.
  • the phase transfer reagent is preferably a quaternary ammonium salt, a crown ether, a polyethylene glycol, or phosphonium salt, and at a suitable temperature.
  • Similar reactions are known in the literature (see for example, I. K. Korobitsyna, O. P. Studzinskii, The Russian Journal of Organic Chemistry (1969), 5(8), 1493-5; A. Halasz, Z. Jambor, A. Levai, C. Nemes, T. Patonay and G. Toth, J. Chem. Soc, Perkin Trans.
  • oxidising agents can also be used.
  • epoxidation is carried out using hydrogen peroxide and a metal hydroxide (especially lithium hydroxide or sodium hydroxide), in methanol at a temperature of between -10 °C and 60 °C.
  • a metal hydroxide especially lithium hydroxide or sodium hydroxide
  • a compound of formula (B) may be prepared from a compound of formula (C) by condensation with a benzaldehyde of formula (D), in the presence of a suitable base and optionally in the presence of a suitable solvent (see for example, A. Lagrange, S. Forestier, G. Lang and B. Luppi, EP368717 A1 ; D. C. Rowlands, US2776239; and E. Tamate, Journal of the Chemical Society of Japan, (1957), 78, 1293-7).
  • the base is a metal hydroxide, such as sodium hydroxide or potassium hydroxide, or a metal alkoxide such as sodium methoxide, sodium ethoxide or potassium tert-butoxide.
  • the solvent is dimethoxyethane, dioxane, tetrahydrofuran, diethyl ether or an alkyl alcohol, such as methanol, ethanol or isopropanol. Mixtures of bases and, in particular, solvents can also be used.
  • Compounds of formula (D) are either known compounds, or can be prepared by formylation of a compound of formula (E) wherein Hal is chlorine, bromine or iodine (preferably bromine or iodine).
  • Preferred compounds of the formula (D) are the compounds of the formula (D1 )
  • R 1 , R 3 and r as defined above and R 20 and R 30 independently of each other, are hydrogen, methyl, methoxy, fluorine, chlorine or bromine.
  • Suitable conditions for effecting the formylation of aryl halides include, for example, the treatment of an aryl halide with a suitable organometallic reagent (such as isopropyl magnesium chloride, n-butyllithium, sec-butyllithium or ie f-butyllithium), or by treatment with a suitable alkali metal or alkali earth metal (such as lithium or magnesium) in a suitable solvent (such as diethyl ether, dimethoxyethane or tetrahydrofuran).
  • a suitable organometallic reagent such as isopropyl magnesium chloride, n-butyllithium, sec-butyllithium or ie f-butyllithium
  • a suitable alkali metal or alkali earth metal such as lithium or magnesium
  • a suitable solvent such as diethyl ether, dimethoxyethane or tetrahydrofuran
  • a compound of formula (D) may be prepared from a compound of formula (E) (wherein Hal can also be a pseudohalogen such as triflate) by treatment with a carbonylating agent (such as carbon monoxide) in the presence of a suitable catalyst, base, and reducing agent (see for example L. Ashfield and C. Barnard, Org. Process Res. Dev., 1 1 (1 ), 39 -43, 2007).
  • a carbonylating agent such as carbon monoxide
  • suitable catalyst, base, and reducing agent see for example L. Ashfield and C. Barnard, Org. Process Res. Dev., 1 1 (1 ), 39 -43, 2007.
  • Compounds of formula (E) are either known compounds (see for example WO 2008/071405), or may be synthesised from known intermediates using standard chemical transformations.
  • a compound of formula (I) may be prepared by reacting a compound of formula (F) (wherein halogen is chlorine, bromine or iodine, preferably chlorine or bromine) with a compound of formula (D), as illustrated in the following reaction scheme.
  • halogen is chlorine, bromine or iodine, preferably chlorine or bromine
  • the reaction of (F) and (D) can be performed with a suitable base, optionally in a suitable solvent, at a suitable temperature.
  • the base is an alkali or alkali earth metal hydroxide (such as sodium hydroxide, lithium hydroxide or potassium hydroxide), an alkali or alkali earth metal alkoxide (such as sodium methoxide, sodium ethoxide or potassium tert- butoxide), an alkali or alkali earth metal carbonate (such as potassium carbonate or sodium carbonate, or sodium bicarbonate), a metal amide (such as lithium diisopropylamide, lithium hexamethyldisilazide or lithium 2,2,6,6-tetramethylpiperidide), an organometallic (such as butyl lithium or ethylmagnesium bromide) or a metal hydride (such as sodium hydride or potassium hydride).
  • an alkali or alkali earth metal hydroxide such as sodium hydroxide, lithium hydroxide or potassium
  • Suitable solvents include chlorinated hydrocarbons, ethers, alcohols, aromatics and various polar aprotic solvents, for example 1 ,2-dimethoxyethane, tetrahydrofuran, 1 ,4-dioxane, diethyl ether, dibutyl ether, dichloromethane, dichloroethane, acetonitrile, dimethyl sulfoxide, benzene, toluene, methanol, ethanol, isopropanol or tert- butanol, and is chosen to be compatible with the base under the reaction conditions.
  • polar aprotic solvents for example 1 ,2-dimethoxyethane, tetrahydrofuran, 1 ,4-dioxane, diethyl ether, dibutyl ether, dichloromethane, dichloroethane, acetonitrile, dimethyl sulfoxide, benzene, toluene
  • the reaction can also be performed under biphasic conditions, in which a phase-transfer reagent is also typically used in 0.001 -50 mol%.
  • the phase transfer reagent is preferably a quaternary ammonium salt, a crown ether, a polyethylene glycol, or phosphonium salt.
  • the reaction is performed using lithium diisopropylamide in tetrahydrofuran at a temperature range of -100°C to 60°C.
  • the conversion of a compound of formula (F) into a compound of formula (I) may be considered to be an example of a Darzens condensation (see for example, W. N. Wassef, M. M.
  • Compounds of formula (F), wherein Y is S, SO and S0 2 are either known compounds (see for example M. Polievka, L. Uhlar, V. Patek, Petrochemia (1973), 13(5-6), 156-60; N. N. Novitskaya, B. V. Flekhter, G. M. Prokhorov, A. S. Lukmanova, G. A. Tolstikov, G. V. Leplyanin, S. A. Lange, M. V. Strashnov, SU 468920 A1 ; P. H. McCabe, W. Routledge, Tetrahedron Letters (1976), (1 ), 85-6; T. S. Chou, C. Y.
  • Step 3 Preparation of 2-(5-Bromo-2-ethylphenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • Step 2 Preparation of 2-(5-Bromo-2-ethylphenyl)-4,6,6-trimethyl-1 ,5-dioxaspiro[2.4]heptan-7- one
  • reaction mixture is stirred at-70°C for a further 20 minutes, followed by addition of 2-ethyl-5-bromobenzaldehyde (23.9g, 0.1 1 mol) as a solution in anhydrous tetrahydrofuran (40ml) dropwise over 20 minutes.
  • 2-ethyl-5-bromobenzaldehyde 23.9g, 0.1 1 mol
  • the reaction mixture is allowed to warm to room temperature then stirred for an additional 30 minutes.
  • the reaction mixture is then quenched by pouring into ice/water (acidified to pH 3 with 2M hydrochloric acid) (500ml) and extracted with ethyl acetate (3 x 100ml). Organic fractions are combined, washed with water and brine, then dried over magnesium sulphate.
  • the crude product is re-dissolved in ethyl acetate (500ml), extracted into 0.5M aqueous potassium carbonate, and washed with additional ethyl acetate (x 2).
  • the aqueous phase is then carefully acidified with concentrated hydrochloric acid, and the product extracted with ethyl acetate (3 x 150ml).
  • Organic fractions are combined, washed with brine then dried over magnesium sulfate, filtered, and the filtrate concentrated in vacuo.
  • the crude product is further purified by flash column chromatography to afford 4-(5-bromo-2-ethylphenyl)-2,2,6-trimethylpyran-3,5-dione (14.1 Og) as a white foam.
  • Step 1 Preparation of 4'-chloro-4-trifluoromethyl-biphenyl-3-carbaldehyde
  • Step 2 Preparation of 4-[1 -(4'-chloro-4-trifluoromethylbiphenyl-3-yl)methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
  • reaction mixture is stirred at 0°C for 30rminut.es and then at ambient temperature for a further 1 hour after which it is partitioned between 1 M hydrochloric acid and dichloromethane.
  • the aqueous phase is extracted again with dichloromethane, than all organics are combined and evaporated to afford 4-[1 -(4'-chloro-4- trifluoromethylbiphenyl-3-yl)methylidene]-2,2,5,5-tetramethyldihyd (2.50g) as a yellow gum. This material is used directly in the next step.
  • Step 3 Preparation of 2-(4'-Chloro-4-trifluoromethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • Step 4 Preparation of 4-(4'-Chloro-4-trifluoromethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran- 3,5-dione
  • Step 2 Preparation of 4-[1 -(5-Bromo-2-iodophenyl)methylidene]-2, 2,5,5- tetramethyldihydrofuran-3-one
  • Step 3 Preparation of 2-(5-Bromo-2-iodophenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • Step 1 Preparation of 4-[1 -(5-Bromo-2-trifluoromethoxyphenyl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
  • Step 2 Preparation of 2-(5-Bromo-2-trifluoromethoxyphenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • reaction mixture is extracted with diethyl ether (x 3), then the organic phase is further washed with saturated aqueous sodium bicarbonate (x 2) then brine. All organics are combined, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to afford 2-(5-bromo-2-trifluoromethoxyphenyl)-4,4,6,6-tetramethyl- 1 ,5-dioxaspiro[2.4]heptan-7-one (6.34g, 86%) as a yellow oil.
  • Step 1 Preparation of 4-Bromo-4'-chloro-biphenyl-3-carbaldehyde
  • Anhydrous N,N- dimethylformamide (1 .71 g, 0.0184mol) is next added dropwise, maintaining temperature below - 40°C, followed by warming to room temperature and quenching with 2M hydrochloric acid (60ml).
  • the reaction mixture is further diluted with diethyl ether, the two phases separated, and the aqueous phase extracted with additional diethyl ether.
  • the combined organic extracts are washed with brine, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo.
  • Step 2 Preparation of 4-[1 -(4-Bromo-4'-chlorobiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
  • reaction mixture When addition is complete the reaction mixture is stirred at 0°C for a further 1 hour, then quenched with 2M hydrochloric acid (50ml). After stirring for an additional 1 hour the solution is diluted with diethyl ether, the two phases separated, and the aqueous phase further extracted with diethyl ether (x 2). The combined organics are further washed with brine, then dried over magnesium sulfate, filtered, and the filtrate concentrated in vacuo to afford 4-[1 -(4-bromo-4'-chlorobiphenyl-3-yl)-methylidene]- 2,2,5,5-tetramethyldihydrofuran-3-one (3.40g, 92%) as a yellow gum.
  • Step 3 Preparation of 2-(4-Bromo-4'-chlorobiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • Step 1 Preparation of 4-[1 -(5-Bromo-2-fluorophenyl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
  • reaction mixture is quenched with 2M hydrochloric acid (50ml), then diluted with diethyl ether and the two phases separated.
  • the aqueous phase is further extracted with diethyl ether (x 2), then all organics are combined, washed with brine and dried over magnesium sulfate. After filtration the filtrate is concentrated in vacuo to afford 4-[1 -(5-bromo-2-fluorophenyl)-methylidene]- 2,2,5,5-tetramethyldihydrofuran-3-one (9.30g, 96%) as a yellow gum.
  • Step 2 Preparation of 2-(5-Bromo-2-fluorophenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • Step 1 Preparation of 4'-chloro-2'-fluoro-4-hydroxybiphenyl-3-carbaldehyde
  • the crude product is purified by flash column chromatography on silica gel, then additionally by flash column chromatography on basic alumina (10% ethyl acetate in hexane as eluant) to afford 4'-chloro- 4-cyclopropyl-2'-fluoro-biphenyl-3-carbaldehyde (7.6g, 36%).
  • Step 4 4-[1 -(4'-Chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
  • Step 5 2-(4'-Chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5-dioxa- spiro[2.4]heptan-7-one
  • Step 6 Preparation of 4-(4'-Chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)-2,2,6,6- tetramethylpyran-3,5-dione
  • Step 1 Preparation of 2',4'-Dichloro-4-hydroxybiphenyl-3-carbaldehyde
  • the crude product is purified by flash column chromatography on silica gel (2-10% ethyl acetate in hexanes as eluant), then additionally by flash column chromatography on basic alumina (10% ethyl acetate in hexane as eluant) to afford 2',4'-dichloro-4-cyclopropylbiphenyl-3- carbaldehyde (1 1 .7g, 54%).
  • Step 4 4-[1 -(2',4'-Dichloro-4-cyclopropylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
  • the two phases are separated, and the aqueous phase is extracted again with diethyl ether (x 2). Organic fractions are combined, washed with brine, then dried over magnesium sulphate. The suspension is filtered and filtrate concentrated in vacuo. The aqueous phase is further acidified with 2M hydrochloric acid then extracted again with diethyl ether (x 2), dried over magnesium sulfate and concentrated in vacuo.
  • Step 6 Preparation of 4-(2',4'-Dichloro-4-cyclopropylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran- 3,5-dione
  • the resulting suspension is stirred at room temperature for 17 days, at which stage further diethyl ether (42ml), lithium perchlorate (22.3g, 0.21 mol) and ytterbium triflate (19.8g, 0.035mol) is added.
  • the reaction mixture is then heated at 27°C (internal temperature) for 1 day, followed by partitioning between diethyl ether and distilled water.
  • the two phases are separated, the aqueous phase is extracted with diethyl ether (x 2), and then all organic fractions are combined, washed with brine then dried over magnesium sulphate.
  • the suspension is filtered and the filtrate is concentrated in vacuo.
  • the crude material is purified by flash column chromatography (ethyl acetate/hexane eluant) to give an oil which is triturated with hexanes to afford 4-(2',4'-dichloro-4-cyclopropylbiphenyl-3-yl)-2,2,6,6- tetramethylpyran-3,5-dione (2.80g) as a white solid.
  • Step 1 Preparation of 2',4'-Dichloro-4-ethylbiphenyl-3-carbaldehyde
  • Step 2 Preparation of 4-[1 -(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
  • Step 3A Preparation of 2-(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • the crude product is extracted with diethyl ether (x 3), washed with saturated sodium bicarbonate, then dried over magnesium sulfate.
  • the residue is purified by flash column chromatography (5% ethyl acetate in isohexane to 25% ethyl acetate in isohexane) to afford 2-(2',4'-dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one as a yellow gum.
  • Step 3B Preparation of 2-(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • reaction mixture is then dilluted with additional toluene, the phases separated, and the organic phase washed again with distilled water (x 2).
  • the organic phase is dried over sodium sulfate then concentrated in vacuo to afford 2-(2',4'- dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one as a white solid.
  • Step 4A Preparation of 4-(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5- dione
  • the crude product is purified by flash column chromatography (5% ethyl acetate in isohexane to 25% ethyl acetate in isohexane) to afford 4-(2',4'-dichloro-4- ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione as a yellow gum.
  • Step 4B Preparation of 4-(2' ! 4'-Dichloro-4-ethylbiphenyl-3-yl)-2 ! 2 ! 6 ! 6-tetramethylpyran-3,5- dione
  • reaction mixture is poured into distilled water, dried over sodium sulfate, then concentrated in vacuo to afford 4- (2',4'-dichloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione.
  • Example P1 1 Preparation of 4-(5-Bromo-2-difluoromethoxyphenyl)-2,2,6,6-tetramethylpyran- 3,5-dione
  • Step 2 Preparation of 4-[1 -(5-Bromo-2-difluoromethoxyphenyl)methylidene]-2, 2,5,5- tetramethyldihydrofuran-3-one
  • Step 3 Preparation of 2-(5-Bromo-2-difluoromethoxyphenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
  • reaction mixture is extracted with diethyl ether (x 3), then the organic phase is further washed with saturated aqueous sodium bicarbonate (x 2) then brine. All organics are combined, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to afford 2-(5-bromo-2-difluoromethoxyphenyl)-4,4,6,6-tetramethyl- 1 ,5-dioxaspiro[2.4]heptan-7-one (7.22g) a yellow gum.
  • the crude product is next extracted into ethyl acetate (x 3), than all organics are combined, washed with brine, and dried over magnesium sulfate.
  • the suspension is filtered and the filtrate is concentrated in vacuo then purified by flash column chromatography (10% to 25% ethyl acetate in hexane as eluant) to give an oil which is triturated with hexanes to afford 4-(5-bromo-2-difluoromethoxyphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (2.08g) as a white solid.

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Abstract

The present invention provides compounds of formula (I) wherein the substituents are as defined in claim 1. The compounds are suitable intermediates in the preparation of herbicidally active 4-phenyl-3,5-pyrandiones, 4-phenyl-3,5-thiopyrandiones and 6-phenylcyclohexane-1,3,5-triones.

Description

Novel Compounds
The present invention relates to novel compounds, their preparation and their use as intermediates in the preparation of herbicidally active substituted 4-phenyl-3,5-pyrandiones, 4-phenyl-3,5-thiopyrandiones and 6-phenylcyclohexane-1 ,3,5-triones.
4-Phenyl-3,5-pyrandiones, 4-phenyl-3,5-thiopyrandiones and 6-phenylcyclohexane-1 ,3,5- triones having herbicidal action and a process for the preparation of these compounds are described, for example, in WO 08/071405.
It has now been discovered that certain substituted epoxyketones can be used as key intermediates in the process for preparing such herbicidally active diones and triones. These are now obtainable in high yield and with considerable advantages over the known processes.
The present invention accordingly relates to compounds of formula I
Figure imgf000002_0001
wherein
R1 is halogen, CrC4alkyl, Ci-C4haloalkyl, C3-C6cycloalkyl, Ci-C4alkoxy, Ci-C4haloalkoxy, d- C4alkylthio, CrC4alkylsulfinyl, Ci-C4alkylsulfonyl;
R2 is hydrogen, halogen, methylsulfonyloxy, Ci-C4haloalkylsulfonyloxy, p-tolylsulfonyloxy, optionally substituted aryl or optionally substituted heteroaryl;
r is 0, 1 , 2 or 3;
R3 if r is 1 , is C C6alkyl, C C6haloalkyl, C C6alkoxy, C C6haloalkoxy, C C6alkylthio, C C6alkylsulfinyl, CrC6alkylsulfonyl, cyano or nitro; or the substituents R3, if r is 2 or 3, independently of each other, are CrC6alkyl, CrC6haloalkyl, CrC6alkoxy, CrC6haloalkoxy, CrC6alkylthio, CrC6alkylsulfinyl, CrC6alkylsulfonyl, cyano or nitro;
Y is O, S, SO, S02 or CO;
R4, R5, R6 and R7, independently of each other, are hydrogen, Ci-C4alkyl, Ci-C4haloalkyl, d- C4alkoxyCi-C4alkyl, Ci-C4alkylthioCi-C4alkyl, Ci-C4alkylsulfinylCi-C4alkyl, d- C4alkylsulfonylCi-C4alkyl, cyclopropyl or cyclopropyl substituted by d- or C2alkyl, d- or C2haloalkyl or halogen; cyclobutyl or cyclobutyl substituted by d- or C2alkyl; oxetanyl or oxetanyl substituted by d- or C2alkyl; C5-C7cycloalkyl or C5-C7cycloalkyl substituted by d- or C2alkyl or d- or C2haloalkyl, where a methylene group of the cycloalkyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; C4- C7cycloalkenyl or C4-C7cycloalkenyl substituted by C or C2alkyl or d- or C2haloalkyl, where a methylene group of the cycloalkenyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; cyclopropylCi-C5alkyl or cyclopropylCi-C5alkyl substituted by d- or C2alkyl, d- or C2haloalkyl or halogen; cyclobutylCi-C5alkyl or cyclobutylCrC5alkyl substituted by d- or C2alkyl; oxetanylCi-C5alkyl or oxetanylCi-C5alkyl substituted by d- or C2alkyl; C5-C7 cycloalkylCi-C5alkyl or C5-C7cycloalkylCrC5alkyl substituted by Cror C2alkyl or d- or C2haloalkyl, where a methylene group of the cycloalkyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; C4- C7cycloalkenylCrC5 alkyl or C4-C7cycloalkenylCrC5alkyl which is substituted by Cr or C2alkyl or d- or C2haloalkyl, where a methylene group of the cycloalkenyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; phenyl or phenyl substituted by d-dalkyl, d-dalkoxy, d-dhaloalkyl, halogen, nitro, cyano, d- dalkylthio, d-dalkylsulfinyl, d-C4alkylsulfonyl or d-C4alkylcarbonyl; benzyl or benzyl substituted by CrC4alkyl, CrC4alkoxy, CrC4haloalkyl, halogen, nitro, cyano, Ci-C4alkylthio, d-dalkylsulfinyl, d-C4alkylsulfonyl or d-C4alkylcarbonyl; heteroaryl or heteroaryl substituted by d-C4alkyl, d-C4alkoxy, Ci-C4haloalkyl, halogen, nitro, cyano, d-dalkylthio, CrC4alkylsulfinyl, d-C4alkylsulfonyl or d-C4alkylcarbonyl; or
R4 and R5, or R6 and R7, are joined to form a 5-7 membered saturated or unsaturated ring in which a methylene group is optionally replaced by an oxygen or sulfur atom, or a 5-7 membered saturated or unsaturated ring substituted by d- or C2alkyl, where a methylene group of the ring is optionally replaced by an oxygen or sulfur atom; or
R4 and R7 are joined to form a 5-7 membered saturated or unsaturated ring unsubstituted or substituted by d- or C2alkyl, d- or C2alkoxy, d-or C2alkoxyd- or C2alkyl, hydroxy, halogen, phenyl or phenyl substituted by d-C4alkyl, d-C4alkoxy, d-C4haloalkyl, halogen, nitro, cyano, d-dalkylthio, d-C4alkylsulfinyl, d-C4alkylsulfonyl or d-C4alkylcarbonyl; heteroaryl or heteroaryl substituted by d-C4alkyl, d-C4alkoxy, d-C4haloalkyl, halogen, nitro, cyano, d-dalkylthio, d-C4alkylsulfinyl, d-C4alkylsulfonyl or d-C4alkylcarbonyl. The present invention also relates to a new process for the preparation of the compounds of formula I.
The invention further relates to a process for the preparation of 4-phenyl-3,5-pyrandiones, 4- phenyl-3,5-thiopyrandiones and 6-phenylcyclohexane-1 ,3,5-triones of formula (A) which is shown below, using the compounds of the formula I as intermediates.
In the substituent definitions of the compounds of the formula I, the alkyl substituents and (halo)alkyl moieties of alkoxy, alkylthio etc. having 1 to 6 carbon atoms are preferably methyl, ethyl, propyl, butyl, pentyl and hexyl, in the form of their straight and branched isomers. Suitable cycloalkyl groups contain 3 to 7 carbon atoms and are for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. Cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl are preferred. Suitable cycloalkene groups contain 4 to 7 carbon atoms and may contain up to 3 double bonds. Preferred halogens are fluorine, chlorine and bromine. Preferred examples of aryls are phenyl and naphthyl. Preferred examples of heteroaryls are thienyl, furyl, pyrrolyl, isoxazolyl, oxazolyl, oxetanyl, isothiazolyl, thiazolyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyrazinyl, triazinyl, oxadiazolyl, thiadiazolyl and pyridazinyl, and, where appropriate, N-oxides and salts thereof. These aryls and heteroaryls can be substituted by one or more substituents, where preferred substituents are halogen, CrC4alkyl, Ci-C4haloalkyl, C2-C4alkenyl, C2-C4haloalkenyl, C2-C4alkynyl, d- C4alkoxy, CrC4haloalkoxy, CrC4alkylthio, CrC4alkylsulfinyl, CrC4alkylsulfonyl, d- C4haloalkylthio, CrC4haloalkylsulfinyl, CrC4haloalkylsulfonyl, nitro or cyano.
In a preferred group of compounds of formula I, R1 is halogen, Ci-C4alkyl, Ci-C4haloalkyl, C3- C6cycloalkyl or Ci-C4-haloalkoxy.
In another preferred group of compounds of formula I, R2 is halogen, aryl or heteroaryl; or aryl or heteroaryl both substituted by halogen, Ci-C4alkyl, Ci-C4haloalkyl, C2-C4alkenyl, C2- C4haloalkenyl, C2-C4alkynyl, Ci-C4alkoxy, Ci-C4haloalkoxy, phenoxy, Ci-C4alkylthio, C C4alkylsulfinyl, CrC4alkylsulfonyl, Ci-C4haloalkylthio, CrC4haloalkylsulfinyl, d- C4haloalkylsulfonyl, C3-C6cycloalkyl, CrC4alkylsulfonyloxy, CrC4haloalkylsulfonyloxy, d- dalkoxyCrdalkyl, d-dalkylthioCrdalkyl, d-dalkylsulfinyld-dalkyl, d- C4alkylsulfonyld-C4alkyl, nitro, cyano, thiocyanato, hydroxy, amino, d-C6alkylamino, d- C6dialkylamino, C3-C6cycloalkylamino, morpholino, thiomorpholino, Ci-C6alkylcarbonylamino, Ci-C6alkoxycarbonylamino, C3-C6 alkenyloxycarbonylamino, C3-C6 alkynyloxycarbonylamino, Ci-C6 alkylaminocarbonylamino, di(Ci-6alkyl)aminocarbonylamino, formyl, CrC6alkyl- carbonyl, C2-C6alkenylcarbonyl, C2-C6alkynylcarbonyl, carboxy, CrC6alkoxycarbonyl, C3- C6alkenyloxycarbonyl, C3-C6alkynyloxycarbonyl, carboxamido, Ci-C6alkylaminocarbonyl, di(Ci-C6alkyl)aminocarbonyl, CrC6alkylcarbonyloxy, Ci-C6alkylaminocarbonyloxy, di(Ci- C6alkyl)aminocarbonyloxy or Ci-C6alkylthiocarbonylamino.
Preferably, R2 in the compounds of formula I is halogen, aryl or heteroaryl; or aryl or heteroaryl both substituted by halogen, CrC4alkyl, CrC4haloalkyl, phenoxy, C2-C4alkenyl, C2-C4haloalkenyl, C2-C4alkynyl, CrC4alkoxy, CrC4haloalkoxy, CrC4alkylthio, C C4alkylsulfinyl, CrC4alkylsulfonyl, CrC4haloalkylthio, CrC4haloalkylsulfinyl, d- C4haloalkylsulfonyl, nitro or cyano.
More preferably, R2 is phenyl, thienyl, furyl, pyrrolyl, isoxazolyl, oxazolyl, isothiazolyl, thiazolyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyrazinyl, triazinyl, pyridazinyl, oxadiazolyl and thiadiazolyl, and N-oxides and salts thereof, where these rings are unsubstituted or substituted by halogen, CrC4alkyl, CrC4haloalkyl, C2-C4alkenyl, C2- C4haloalkenyl, C2-C4alkynyl, CrC4alkoxy, CrC4haloalkoxy, CrC4alkylthio, CrC4alkylsulfinyl, CrC4alkylsulfonyl, CrC4haloalkylthio, Ci-C4haloalkylsulfinyl, CrC4haloalkylsulfonyl, nitro or cyano.
In even more preferred compounds of the formula I, R2 is phenyl or pyridyl or phenyl or pyridyl both substituted by halogen, nitro, cyano, Ci-C2alkyl, Ci-C2haloalkyl, Ci-C2alkoxy or CrC2haloalkoxy.
In an especially preferred group of compounds, R2 is phenyl substituted at the para-position by halogen (in particular chlorine) and is optionally further substituted by halogen, nitro, C C2alkyl, Ci-C2haloalkyl, Ci-C2alkoxy or Ci-C2haloalkoxy.
Preferably, R3 is hydrogen (r is 0) or CrC6alkyl, especially hydrogen.
Preferably, R3, if r is 1 , is C C3alkyl. Preferred are those compounds of the formula I, wherein R4, R5, R6 and R7, independently of each other, are hydrogen, CrC4alkyl, Ci-C4haloalkyl, Ci-C4alkoxyCrC4 alkyl, d- C4alkylthioC C4alkyl, C1-C4alkylsulfinylC1-C4alkyl, Ci-C4alkylsulfonylC C4alkyl; C5- C7cycloalkyl or C5-C7cycloalkyl substituted by C or C2alkyl or d- or C2haloalkyl and in which a methylene group is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; C5-C7cycloalkylCi-C5alkyl or C5-C7cycloalkylCi-C5alkyl substituted by C C2alkyl or d- or C2haloalkyl and in which a methylene group is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group.
More preferably, R4, R5, R6 and R7, independently of each other, are hydrogen, Ci-C2alkyl, CrC2haloalkyl or Ci-C2alkoxyCrC2alkyl.
In a preferred group of compounds of the formula (I), R1 is ethyl, methyl or cyclopropyl, R2 is phenyl or phenyl substituted by halogen or Ci-C2alkyl, R3 is hydrogen, R4, R5, R6 and R7, independently of each other, are CrC2alkyl.
In another preferred group of compounds of the formula (I), Ri is methyl, ethyl, cyclopropyl, n-propyl, halogen, trifluoromethoxy, difluoromethoxy and trifluoromethyl, R4, R5, R6 and R7, independently of each other, are hydrogen, methyl and ethyl, R2 is halogen, phenyl substituted by halogen, Ci-C4alkyl, Ci-C4haloalkyl, Ci-C4haloalkoxy or Ci-C4alkoxy, R3 is hydrogen and Y is oxygen, where
more preferably, Ri is ethyl or cyclopropyl, R4, R5, R6 and R7 are methyl, R2 is phenyl substituted once or twice by fluorine, chlorine, methoxy or methyl, R3 is hydrogen and Y is oxygen, where
most preferably, Ri is ethyl, R4, R5, R6 and R7are methyl, R2 is 4-chlorophenyl, 2,4- dichlorophenyl and 2-fluoro-4-chlorophenyl, R3 is hydrogen and Y is oxygen.
In another preferred group of compounds of the formula (I), Ri is ethyl, trifluoromethyl, cyclopropyl, difluoromethoxy, trifluoromethoxy, fluoro, bromine or iodine, R4, R5, R6 and R7, independently of each other, are hydrogen or methyl, R2 is bromine, 4-chlorophenyl, 2-fluoro- 4-chlorophenyl, 2,4-di-chlorophenyl, R3 is hydrogen and Y is O, where
more preferably, Ri is ethyl, cyclopropyl, R4, R5, R6 and R7 are methyl, R2 is bromine, 4- chlorophenyl, 2-fluoro-4-chlorophenyl or 2,4-di-chlorophenyl, R3 is H and Y is O. ln a further aspect of the invention, it has now been found, surprisingly, that the compounds of formula I can easily be converted into 4-phenyl-3,5-pyrandiones, 4-phenyl-3,5-thio- pyrandiones and 6-phenylcyclohexane-1 ,3,5-triones of formula (A) below in the presence of an acid.
Reaction Scheme 1
Figure imgf000007_0001
Suitable acids include Bronsted acids such as mineral acids and organic acids, for example sulfuric acid, hydrochloric acid, hydrogen chloride, p-toluenesulfonic acid, acetic acid and formic acid, and Lewis acids such as metal halides, for example boron trifluoride, aluminium chloride, iron chloride, tin(IV) chloride, zinc chloride, zinc bromide, lithium perchlorate, as well as metal triflates such as scandium triflate and ytterbium triflate. Mixtures of such acids can also be used. The conversion of a compound of formula (I) into a compound of formula (A) may be considered to be an example of a semi-Pinacol rearrangement (see for example M. Paulson, M. Daliya and C. Asokan, Synth. Commun. (2007), 37(5), 661 -665; S. Sankararaman and J. Nesakumar, J. Chem. Soc, Perkin Trans. 1 , (1999), (21 ), 3173-3175; K. Rehse and R. Bienfait, Archiv der Pharmazie, (1984), 317(5), 385-93; H. Kamath, A. Sahasrabudhe, B. Bapat and S. Kulkarni, Indian J. Chem., Section B: (1981 ), 20B(12), 1094- 6; G. Buchanan and D. Jhaveri, J. Org. Chem. (1961 ), 26 4295-9; and H. House, Richard L. Wasson, J. Am. Chem. Soc, (1956), 78, 4394-400), but such a transformation is unknown for compounds of type (I). The reactions conditions which are useful in the process of the present invention are similar to those described in the literature mentioned above or can be derived by those skilled in the art. Suitable solvents are those chosen to be compatible with the acid used, and include chlorinated hydrocarbons, alcohols, ethers, aromatics and organic acids, for example dichloromethane, dichloroethane, diethyl ether, acetic acid, formic acid, toluene, benzene, methanol, ethanol, isopropanol and tetrahydrofuran. Mixtures of solvents can also be used. Preferably the reaction is performed using concentrated sulphuric acid in dichloroethane. The preferred reaction temperature is within the range of between -50°C and 83°C, even more preferably between -50°C and 40°C. Additional preferred reaction conditions are the use of lithium perchlorate solution in ether in combination with 0.1 - 100mol% ytterbium triflate as acid, at a temperature range between 0°C and 60°C.
The present process is distinguished over the art mentioned above by:
(a) easy accessibility of the starting materials,
(b) a short reaction sequence,
(c) avoidance of highly toxic reagents
(d) high volume concentration of the reactants (demonstrated up to 20%, example P1 step
4).
(e) widely - especially in the 2 and 5 positions - substituted phenyl derivatives as starting compounds,
(f) generally high product yields, and
(g) economic and ecological advantages derived from the fact that the process can be used as a partial step in a continuous reaction procedure for the preparation of 4-phenyl-3,5- pyrandiones, 4-phenyl-3,5-thiopyrandiones and 6-phenylcyclohexane-1 ,3,5-triones of formula (A), which are known to exhibit herbicidal properties.
The present preparation process is therefore suitable especially for the cost-effective, large- scale preparation of the diones and triones of formula (A).
The compounds of formula (I), and this is another aspect of the present invention, can be obtained by the epoxidation of compounds of formula (B), as is illustrated in the following reaction scheme:
Figure imgf000008_0001
wherein Y, R1, R2, R3, r, R4, R5, R6 and R7 are as defined above. The compounds of the formula (B) are novel and have been especially designed as intermediates for the synthesis of the compounds of formula (I) and form another aspect of the invention.
Epoxidation may be effected by treatment of a compound of formula (B) with a suitable oxidising agent such as an organic peroxide or metal hyperchlorite, for example dimethyldioxirane, sodium hypochlorite, hydrogen peroxide, tert-butyl peroxide or trifluoroperacetic acid, optionally in combination with a suitable base (such as an alkali metal hydroxide or carbonate, alkaline earth metal hydroxide or carbonate, or an amine base such as 1 ,8-diazabicyclo[5.4.0]-undec-7-ene), optionally in a suitable solvent (such as an alcohol, a halogenated hydrocarbon or an aromatic compound, for example methanol, ethanol, dichloromethane or toluene) and at a suitable temperature. The reaction can also be performed under biphasic conditions, in which a phase-transfer reagent is also typically used in 0.001 -50 mol%. The phase transfer reagent is preferably a quaternary ammonium salt, a crown ether, a polyethylene glycol, or phosphonium salt, and at a suitable temperature. Similar reactions are known in the literature (see for example, I. K. Korobitsyna, O. P. Studzinskii, The Russian Journal of Organic Chemistry (1969), 5(8), 1493-5; A. Halasz, Z. Jambor, A. Levai, C. Nemes, T. Patonay and G. Toth, J. Chem. Soc, Perkin Trans. 1 , (1996), (4), 395-400; N. Yousif, F. Gad, A. Fahmy, M. Amine and H. Sayed, Phosphorus, Sulfur and Silicon and the Related Elements (1996), 1 17, 1 1 -19; T. Ooi, D. Ohara, M. Tamura and K. Maruoka, J. Am. Chem. Soc, (2004), 126(22), 6844-6845; A. Amr, H. Hayam and M. Abdulla, Archiv der Pharmazie, (2005), 338(9), 433-440; K. Drauz, S. M. Roberts, T. Geller and A. Dhanda, US6538105 B1 ; and L. S. Chagonda and B. A. Marples, J. Chem. Soc. Perkin 1 , 1988, 875-879). Mixtures of oxidising agents, bases, and solvents can also be used. Preferably, epoxidation is carried out using hydrogen peroxide and a metal hydroxide (especially lithium hydroxide or sodium hydroxide), in methanol at a temperature of between -10 °C and 60 °C.
A compound of formula (B) may be prepared from a compound of formula (C) by condensation with a benzaldehyde of formula (D), in the presence of a suitable base and optionally in the presence of a suitable solvent (see for example, A. Lagrange, S. Forestier, G. Lang and B. Luppi, EP368717 A1 ; D. C. Rowlands, US2776239; and E. Tamate, Journal of the Chemical Society of Japan, (1957), 78, 1293-7).
Figure imgf000010_0001
Preferably the base is a metal hydroxide, such as sodium hydroxide or potassium hydroxide, or a metal alkoxide such as sodium methoxide, sodium ethoxide or potassium tert-butoxide. Preferably the solvent is dimethoxyethane, dioxane, tetrahydrofuran, diethyl ether or an alkyl alcohol, such as methanol, ethanol or isopropanol. Mixtures of bases and, in particular, solvents can also be used.
Compounds of formula (C), wherein Y is O, are known compounds (see for example M. Newman and W. Reichle, Org. Synth. Coll. Vol. V., (1973), 1024; Y. Zal'kind, E. Venus- Danilova and V. Ryabtseva, Russian Journal of General Chemistry, (1950), 20, 2222-9; M. Bertrand, J. Dulcere, G. Gil, J. Grimaldi and P. Sylvestre-Panthet, Tetrahedron Letters (1976), (18), 1507-8), or may be prepared from known compounds by known methods. Compounds of formula (C), wherein Y is C=0, are known compounds (see for example N. J. Turro, D. R. Morton, E. Hedaya, M. E. Kent, P. D'Angelo, P. Schissel, Tetrahedron Letters (1971 ), (27), 2535-8; P. A. Krapcho, D. R. Rao, M. P. Silvon, B. Abegaz, Journal of Organic Chemistry (1971 ), 36(25), 3885-90; S. N. Crane, T. J. Jenkins, D. J. Burnell, Journal of Organic Chemistry (1997), 62(25), 8722-8729; S. N. Crane, D. J. Burnell, Journal of Organic Chemistry (1998), 63(4), 1352-1355; S. N. Crane, D. J. Burnell, Journal of Organic Chemistry (1998), 63(16), 5708-5710; C. E. Elliott, D. O. Miller, D. J. Burnell, Journal of the Chemical Society, Perkin Transactions 1 (2002), (2), 217-226), or may be prepared from known compounds by known methods. Compounds of formula (C), wherein Y is S, SO or S02 are known compounds (see for example E. R. Buchman, H. Cohen, Journal of the American Chemical Society (1944), 66, 847-8; A. W. D. Avison, F. Bergel, J. W. Haworth, US2408519: K. G. Mason, M. A. Smith, E. S. Stern, EJ. A. Elvidge, Journal of the Chemical Society [Section] C: Organic (1967), (21 ), 2171 -6; T. A. Magee, Thomas A. DE 2033454; I. Tabushi, Y. Tamaru, Z. Yoshida, T. Sugimoto, Journal of the American Chemical Society (1975), 97(10), 2886-91 ; P. E. Aldrich, G. H. Berezin, B. I. Dittmar, I. Bruce, DE 2516554; I. Tabushi, Y. Tamaru, Z. Yoshida, Bulletin of the Chemical Society of Japan (1978), 51 (4), 1 178-82; D. N. Reinhoudt, J. Geevers, W. P. Trompenaars, S. Harkema, G. J. Van Hummel, Journal of Organic Chemistry (1981 ), 46(2), 424-34; F. Duus, Synthesis (1985), (6-7), 672-4; J. Schatz, Science of Synthesis (2002), 9, 287-422), or may be prepared from known compounds by known methods.
Compounds of formula (D) are either known compounds, or can be prepared by formylation of a compound of formula (E) wherein Hal is chlorine, bromine or iodine (preferably bromine or iodine).
Figure imgf000011_0001
(E) (D)
wherein R1, R2, R3 and r and Hal is halogen as defined above. Preferred compounds of the formula (D) are the compounds of the formula (D1 )
Figure imgf000011_0002
wherein R1, R3 and r as defined above and R20 and R30, independently of each other, are hydrogen, methyl, methoxy, fluorine, chlorine or bromine. The compounds of the formula (D) as far as they are novel and the novel compounds of the formula (D1 ) have been especially designed as intermediates for the synthesis of the compounds of formula (I) and form another aspect of the invention.
Suitable conditions for effecting the formylation of aryl halides are known, and include, for example, the treatment of an aryl halide with a suitable organometallic reagent (such as isopropyl magnesium chloride, n-butyllithium, sec-butyllithium or ie f-butyllithium), or by treatment with a suitable alkali metal or alkali earth metal (such as lithium or magnesium) in a suitable solvent (such as diethyl ether, dimethoxyethane or tetrahydrofuran). The resulting arylmetal reagent is then reacted with a suitable formylating agent such as N,N- dimethylformamide or /V-formylmorpholine. Alternatively a compound of formula (D) may be prepared from a compound of formula (E) (wherein Hal can also be a pseudohalogen such as triflate) by treatment with a carbonylating agent (such as carbon monoxide) in the presence of a suitable catalyst, base, and reducing agent (see for example L. Ashfield and C. Barnard, Org. Process Res. Dev., 1 1 (1 ), 39 -43, 2007). Compounds of formula (E) are either known compounds (see for example WO 2008/071405), or may be synthesised from known intermediates using standard chemical transformations.
Alternatively a compound of formula (I) may be prepared by reacting a compound of formula (F) (wherein halogen is chlorine, bromine or iodine, preferably chlorine or bromine) with a compound of formula (D), as illustrated in the following reaction scheme.
Figure imgf000012_0001
The reaction of (F) and (D) can be performed with a suitable base, optionally in a suitable solvent, at a suitable temperature. Preferably the base is an alkali or alkali earth metal hydroxide (such as sodium hydroxide, lithium hydroxide or potassium hydroxide), an alkali or alkali earth metal alkoxide (such as sodium methoxide, sodium ethoxide or potassium tert- butoxide), an alkali or alkali earth metal carbonate (such as potassium carbonate or sodium carbonate, or sodium bicarbonate), a metal amide (such as lithium diisopropylamide, lithium hexamethyldisilazide or lithium 2,2,6,6-tetramethylpiperidide), an organometallic (such as butyl lithium or ethylmagnesium bromide) or a metal hydride (such as sodium hydride or potassium hydride). Suitable solvents include chlorinated hydrocarbons, ethers, alcohols, aromatics and various polar aprotic solvents, for example 1 ,2-dimethoxyethane, tetrahydrofuran, 1 ,4-dioxane, diethyl ether, dibutyl ether, dichloromethane, dichloroethane, acetonitrile, dimethyl sulfoxide, benzene, toluene, methanol, ethanol, isopropanol or tert- butanol, and is chosen to be compatible with the base under the reaction conditions. The reaction can also be performed under biphasic conditions, in which a phase-transfer reagent is also typically used in 0.001 -50 mol%. The phase transfer reagent is preferably a quaternary ammonium salt, a crown ether, a polyethylene glycol, or phosphonium salt. Most preferably the reaction is performed using lithium diisopropylamide in tetrahydrofuran at a temperature range of -100°C to 60°C. The conversion of a compound of formula (F) into a compound of formula (I) may be considered to be an example of a Darzens condensation (see for example, W. N. Wassef, M. M. El-Barky, Journal of Chemical Research, Synopses (1990), (12), 402-3; J. Li, X. Liu, X. Li, Youji Huaxue (2007), 27(1 1 ), 1428-1431 ; Y. Tong, Y. Cheng, X. Guo, S. Wu, Hecheng Huaxue (2007), 15(1 ), 102-104; C. Parmenon, J. Guillard, D. Caignard, N. Hennuyer, B. Staels, V. Audinot-Bouchez, J. Boutin, C. Dacquet, A. Ktorza, M. Viaud-Massuard, Bioorganic & Medicinal Chemistry Letters (2008), 18(5), 1617-1622; H. Xiao, X. Han, J. Xiong, Faming Zhuanli Shenqing Gongkai Shuomingshu (2007), p1 1 ; J. M. Concellon, E. Bardales, R. Llavona, Journal of Organic Chemistry (2003), 68(4), 1585-1588), but such a transformation is unknown for compounds of type (F).
Compounds of formula (F), wherein Y is O, are either known compounds (see for example H. Richet, R. Dulou, R., G. Dupont, Bulletin de la Societe Chimique de France (1947), 693-9; H. Richet, Ann. Chim. [12] (1948), 3 317-54; I. K. Korobitsyna, Yu. K. Yur'ev, Yu. A. Cheburkov, E. M. Lukina, Russian Journal of General Chemistry (1955), 25, 734-8; I. K. Korobitsyna, Yu. K. Yur'ev, Yu. A. Cheburkov, E. M. Lukina, Russian Journal of General Chemistry (1955), 25, 690-702; F. Leonard, A. Wajngurt, H. Horn, Journal of Organic Chemistry (1956), 21 , 1400-4; I. K. Korobitsyna, I. G. Zhukova, V. A. Kuvshinova, N. N. Gaidamovich, Yu. K. Yur'ev, Doklady Akademii Nauk SSSR (1957), 1 14, 327-30; I. K. Korobitsyna, I. G. Zhukova, I. G, Yu. K. Yur'ev, Russian Journal of General Chemistry (1959), 29, 2190-6; I. K. Korobitsyna, L. L. Rodina, L. M. Stashkova, Chemistry of Heterocyclic Compounds (1966), (6), 843-7; G. Hoehne, F. Marschner, K. Praefcke, P. Weyerstahl, Chem. Ber. (1975), 108(2), 673-82; H. Saimoto, T. Hiyama, H. Nozaki, Bull. Chem. Soc. Jpn., (1983), 56(10), 3078-87; A. M. Zvonok, N. M. Kuz'menok, I. G. Tishchenko, L. S. Stanishevskii, Russian Journal of General Chemistry (1985), 21 (6), 1330-4) or can be prepared from compounds of formula (C) under known conditions. Compounds of formula (F), wherein Y is S, SO and S02, are either known compounds (see for example M. Polievka, L. Uhlar, V. Patek, Petrochemia (1973), 13(5-6), 156-60; N. N. Novitskaya, B. V. Flekhter, G. M. Prokhorov, A. S. Lukmanova, G. A. Tolstikov, G. V. Leplyanin, S. A. Lange, M. V. Strashnov, SU 468920 A1 ; P. H. McCabe, W. Routledge, Tetrahedron Letters (1976), (1 ), 85-6; T. S. Chou, C. Y. Tsai, Tetrahedron Letters (1992), 33(29), 4201 -4), or can be prepared from compounds of formula (C) under known conditions. Compounds of formula (F), wherein Y is C=0, can be prepared from compounds of formula (C) under similar halogenation conditions.
The Examples that follow further illustrate the invention without limiting it. Preparation Examples:
Example P1 : Preparation of 4-(5-bromo-2-ethylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione
Figure imgf000014_0001
Step 1 : Preparation of 5-Bromo-2-ethyl-benzaldehyde
Figure imgf000014_0002
To a solution of 4-bromo-1 -ethyl-2-iodobenzene (31.8g, 103mmol) (described in WO 2008/071405) in anhydrous tetrahydrofuran (250ml) at -20°C is added isopropyl magnesium chloride (55ml, 1 10mmol, 2M solution in tetrahydrofuran) dropwise over 10 minutes. Once the addition is complete the reaction mixture is stirred at -20°C for 3 hours, followed by dropwise addition of anhydrous Λ/,/V-dimethylformamide (16.0ml, 200mmol). The reaction mixture is stirred at room temperature for a further 2.5 hours, then left to stand overnight. 2M hydrochloric acid (90ml) is added and the crude product is extracted into dichloromethane. Organics are combined, dried over magnesium sulfate then filtered and the filtrate evaporated under reduced pressure to afford 5-bromo-2-ethyl-benzaldehyde (21.20g) as an orange liquid. Step 2: Preparation of 4-(5-Bromo-2-ethylbenzylidene)-2,2,5,5-tetramethyldihydrofuran-3-one
Figure imgf000015_0001
To an ice-cold solution of dihydro-2,2,5,5-tetramethyl-3(2H)-furanone (13.4g, 94.34mmol) in anhydrous 1 ,2-dimethoxyethane (32ml) is added sodium methoxide (5.6g, 103.8mmol) in one portion, and the reaction mixture is stirred at this temperature for 5 minutes. To the resulting slurry is then added a solution of 5-bromo-2-ethyl-benzaldehyde (20g, 94.34mmol) in 1 ,2-dimethoxyethane (32ml) dropwise over 10 minutes. The solution is next stirred at 0°C for 1 hour, then diluted with diethyl ether and washed with 2M hydrochloric acid (x 2). Organic fractions are combined, dried over magnesium sulphate, filtered and the filtrate evaporated in vacuo to afford 4-(5-bromo-2-ethylbenzylidene)-2,2,5,5-tetramethyldihydrofuran-3-one (30.2g) as a yellow liquid.
Step 3: Preparation of 2-(5-Bromo-2-ethylphenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000015_0002
To a solution of 4-(5-bromo-2-ethylbenzylidene)-2,2,5,5-tetramethyldihydrofuran-3-one (32.07g, 95.15mmol) in methanol (1570 ml) at 35 °C is added 50% aqueous hydrogen peroxide (8.10ml, 142.73mmol), followed immediately by a solution of 2M aqueous lithium hydroxide (9.51 ml, 19.03mmol). This reaction mixture is stirred at 35°C for exactly 1 hour, then quenched with saturated sodium metabisulfite (340ml) and distilled water (340ml). After stirring at room temperature for 15 minutes solvents are then concentrated in vacuo (to approximately 500ml), over which time the product precipitates as a yellow solid. To this suspension is added distilled water (500ml), and the product is isolated by filtration. After additional washing with distilled water the solid is dried under vacuum overnight to afford 2- (5-bromo-2-ethylphenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (29.30g) as a yellow solid which is used without purification in the next step.
1 H NMR (CDCIs): δ 7.47-7.40 (m, 2H), 7.10 (d, 1 H), 4.43 (s, 1 H), 2.62-2.60 (m, 2H), 1 .40 (s, 3H), 1 .37 (s, 3H), 1 .30-1 .20 (m, 6H), 0.78 (s, 3H).
Step 4: Preparation of 4-(5-bromo-2-ethylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione
Figure imgf000016_0001
To an ice-cold solution of concentrated sulphuric acid (2ml) is added a second solution of 2- (5-bromo-2-ethylphenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (0.995g, 2.82mmol) in 1 ,2-dichloroethane (2ml) dropwise over 5 minutes. This biphasic mixture is stirred vigorously for 1 hour at 0°C, then poured into ice-cold water (15ml). This aqueous mixture is then concentrated under vacuum to remove all organic volatiles, producing a free- flowing solid. The solid is filtered, dried under vacuum, then washed with hexanes to afford 4- (5-bromo-2-ethylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (0.81 g) as a cream-coloured solid.
1 H NMR (CDCI3): 57.48 (1 H, dd), 7.23-7.21 (2H, m), 5.60 (1 H, s), 2.45-2.33 (2H, m), 1.60 (6H, d), 1.48 (6H, d), 1.10 (3H, t).
Example P2: Preparation of 4-(5-Bromo-2-ethylphenyl)-2,2,6-trimethylpyran-3,5-dione
Figure imgf000017_0001
Step 1 : Preparation of 4-Bromo-2,2,5-trimethyldihydro-furan-3-one
Figure imgf000017_0002
To a solution of acetic acid 4-bromo-2,2,5-trimethyl-2,5-dihydrofuran-3-yl ester (19.14g, 0.1 1 mol) (described in T.Hiyama et al. Bull. Chem. Soc. Jpn., 56, 3078-3087 (1983)) in anhydrous chloroform (75ml) at -20°C is added a solution of bromine (18.00g, 0.1 1 mol) in anhydrous chloroform (200ml) dropwise over 45 minutes. After stirring at this temperature for 30 minutes the reaction mixture was allowed to warm to room temperature, then further stirred for 1 hour. After dilution with chloroform (250ml) the organic phase is washed with dilute aqueous sodium bicarbonate then brine, and the phases separated. Organics solvents are removed under reduced pressure to afford 4-bromo-2,2,5-trimethyldihydro-furan-3-one (23.50g) as a dark orange oil. This material is used without purification in the next step.
Step 2: Preparation of 2-(5-Bromo-2-ethylphenyl)-4,6,6-trimethyl-1 ,5-dioxaspiro[2.4]heptan-7- one
Figure imgf000018_0001
To a solution of lithium diisopropylamide (0.12mol) in anhydrous tetrahydrofuran (150ml) at -70°C is added a second solution of 4-bromo-2,2,5-trimethyl-4,5-dihydro-3(2H)-furanone (23.5g, 0.1 1 mol) in anhydrous tetrahydrofuran (40ml), at such a rate as to keep the internal temperature below -65°C. Once the addition is complete the reaction mixture is stirred at-70°C for a further 20 minutes, followed by addition of 2-ethyl-5-bromobenzaldehyde (23.9g, 0.1 1 mol) as a solution in anhydrous tetrahydrofuran (40ml) dropwise over 20 minutes. After further stirring at -70°C for 20 minutes the reaction mixture is allowed to warm to room temperature then stirred for an additional 30 minutes. The reaction mixture is then quenched by pouring into ice/water (acidified to pH 3 with 2M hydrochloric acid) (500ml) and extracted with ethyl acetate (3 x 100ml). Organic fractions are combined, washed with water and brine, then dried over magnesium sulphate. The suspension is filtered, and the filtrate is concentrated in vacuo to afford a mixture of 2-(5-bromo-2-ethylphenyl)-4,6,6-trimethyl-1 ,5- dioxaspiro[2.4]heptan-7-one and 2-ethyl-5-bromobenzaldehyde (40.50g), in an approximate 3:1 ratio. This material is used without purification in the next step.
1 H NMR (CDCIs): δ 7.47 (m, 1 H), 7.41 (m, 1 H), 7.10 (d, 1 H), 4.47 (q, 1 H), 4.39 (s, 1 H), 2.60 (q, 2H), 1.38 (s, 3H), 1.35 (s, 3H), 1.23 (t, 3H), 0.70 (d, 3H).
Step 3: Preparation of 4-(5-Bromo-2-ethylphenyl)-2,2,6-trimethylpyran-3,5-dione
Figure imgf000018_0002
To ice-cold concentrated sulphuric acid (50ml) is added a solution of crude 2-(5-bromo-2- ethylphenyl)-4,6,6-trimethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (40g) in 1 ,2-dichloroethane (50ml) over 20 minutes. After further stirring at 0°C for 1 hour the reaction mixture is carefully poured into ice (500g), and the two phases separated. The aqueous phase is further extracted with dichloromethane (2 x 100ml), then all organic fractions are combined, washed with water, and concentrated under reduced pressure. The crude product is re-dissolved in ethyl acetate (500ml), extracted into 0.5M aqueous potassium carbonate, and washed with additional ethyl acetate (x 2). The aqueous phase is then carefully acidified with concentrated hydrochloric acid, and the product extracted with ethyl acetate (3 x 150ml). Organic fractions are combined, washed with brine then dried over magnesium sulfate, filtered, and the filtrate concentrated in vacuo. The crude product is further purified by flash column chromatography to afford 4-(5-bromo-2-ethylphenyl)-2,2,6-trimethylpyran-3,5-dione (14.1 Og) as a white foam.
1 H NMR (CDCIs): 51 .08 (m, 3H), 1 .38-1.62 (m, 9H), 2.25 (m, 2H), 4.38 and 4.71 (m, 1 H), 5.72 and 5.83 (2 x br. s, 1 H), 7.20 (m, 2H), 7.48 (m, 1 H).
Example P3: 4-(4'-Chloro-4-trifluoromethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione
Step 1 : Preparation of 4'-chloro-4-trifluoromethyl-biphenyl-3-carbaldehyde
Figure imgf000019_0002
To a mixture of 3-chloro-6-trifluoromethylbenzaldehyde (1 .0g, 4.79mmol), 4-chlorophenyl boronic acid (1 .12g, 7.19mmol), potassium phosphate (2.03g, 9.59mmol), dicyclohexyl-(2',6'- dimethoxy-biphenyl-2-yl)-phosphane (0.079g, 0.19mmol) and palladium acetate (0.022g, 0.096mmol) is added degassed toluene (9ml), then the mixture is further purged with nitrogen. The suspension is next sealed then stirred at ambient temperature for 5 minutes, than heated at 160°C for 1 hour under microwave irradiation. After cooling the reaction mixture is partitioned between 2M hydrochloric acid and dichloromethane, and the aqueous phase further extracted with dichloromethane (x 2). The organic fractions are combined then evaporated under reduced pressure to yield a crude product which is purified by flash column chromatography (100% hexane to 10% ethyl acetate in hexanes as eluant) to afford 4'- chloro-4-trifluoromethyl-biphenyl-3-carbaldehyde (1 .78g) as an orange gum. This material is used directly in the next step.
Step 2: Preparation of 4-[1 -(4'-chloro-4-trifluoromethylbiphenyl-3-yl)methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000020_0001
To an ice-cold solution of 2,2,5,5-tetramethyldihydrofuran-3-one (0.887g, 6.25mmoles) in 1 ,2-dimethoxyethane (10ml) is added sodium methoxide (0.405g, 7.50mmoles) in one portion. The reaction mixture is stirred at 0°C for 30 minutes, followed by the dropwise addition of 4'-chloro-4-trifluoromethylbiphenyl-3-carbaldehyde (1 .779g, 6.25mmoles) as a solution in 1 ,2-dimethoxyethane (10ml). The reaction mixture is stirred at 0°C for 30rminut.es and then at ambient temperature for a further 1 hour after which it is partitioned between 1 M hydrochloric acid and dichloromethane. The aqueous phase is extracted again with dichloromethane, than all organics are combined and evaporated to afford 4-[1 -(4'-chloro-4- trifluoromethylbiphenyl-3-yl)methylidene]-2,2,5,5-tetramethyldihyd (2.50g) as a yellow gum. This material is used directly in the next step.
Step 3: Preparation of 2-(4'-Chloro-4-trifluoromethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000021_0001
To a solution of 4-[1 -(4'-chloro-4-trifluoromethylbiphenyl-3-yl)methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (2.50g, 6.12mmol) in methanol (75ml) at 35 °C is added 50% aqueous hydrogen peroxide solution (0.70ml, 12.2mmol), followed immediately by a solution of 2M aqueous lithium hydroxide (0.76ml, 1.52mmol). This mixture is stirred at 35 °C for 45 minutes, then allowed to cooled to room temperature and quenched with saturated sodium metabisulfite solution. The crude product is extracted with diethyl ether (x 2), then all organics are combined and dried over magnesium sulfate. After filtration the filtrate is concentrated in vacuo to afford 2-(4'-chloro-4-trifluoromethylbiphenyl-3-yl)-4,4,6,6- tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (2.59g) as a yellow gum. This material is used directly in the next step.
Step 4: Preparation of 4-(4'-Chloro-4-trifluoromethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran- 3,5-dione
Figure imgf000021_0002
To an ice-cold solution of crude 2-(4'-chloro-4-trifluoromethylbiphenyl-3-yl)-4,4,6,6- tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (2.59g, 6.12mmoles) in dichloroethane (25ml) is added concentrated sulfuric acid (5ml), followed by stirring at this temperature for 2 hours. The reaction mixture is poured into ice, extracted with dichloromethane (x 2), and the combined organics are evaporated under reduced pressure to yield a brown gum. Purification by flash column chromatography (isohexane to 30% ethyl acetate in isohexane as eluant) then reverse phase preparative HPLC affords 4-(4'-chloro-4- trifluoromethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione (0.370g) as a white solid.
1 H NMR (CDCIs): 57.85 (d, 1 H), 7.69 (d, 1 H), 7.53 (d, 2H), 7.44 (d, 2H), 7.39 (s, 1 H), 1.60 (app. d, 6H), 1 .48 (s, 6H)
Example P4: Preparation of 4-(5-Bromo-2-iodophenyl)-2,2,6,6-tetramethylpyran-3,5-dione
Figure imgf000022_0001
Step 1 : Preparation of 5-Bromo-2-iodobenzaldehyde
Figure imgf000022_0002
To a solution of 5-bromo-2-iodobenzonitrile (5.00g, 16.00mmoles) in anhydrous tetrahydrofuran (80ml) at -80°C is added diisobutyl aluminium hydride (16.0ml, 16.0mmoles, 1 M solution in toluene) dropwise over 10 minutes. The reaction mixture is stirred at -80°C for a 1 hour, then allowed to warm to ambient temperature and stir overnight. Additional diisobutyl aluminium hydride (16.0ml, 16.0mmoles, 1 M solution in toluene) is next added dropwise at room temperature, and the reaction mixture further stirred for 1 hour. After careful quenching with 2M hydrochloric acid (cooling in ice bath), the crude product is extracted with ethyl acetate (x 2), then all organics are combined and dried over magnesium sulfate and filtered. The filtrate is evaporated under reduced pressure then purified by flash column chromatography (isohexane to 10% ethyl acetate in isohexane eluant) to afford 5-bromo-2- iodobenzaldehyde (0.85g).
Step 2: Preparation of 4-[1 -(5-Bromo-2-iodophenyl)methylidene]-2, 2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000023_0001
To an ice-cold solution of 2,2,5,5-tetramethyldihydrofuran-3-one (0.388g, 2.73mmoles) in anhydrous 1 ,2-dimethoxyethane (5ml) is added sodium methoxide (0.177g, 3.27mmoles) in one portion. The reaction mixture is stirred for 5 minutes at this temperature, followed by the dropwise addition of 5-bromo-2-iodo-benzaldehyde (0.850g, 2.73mmoles) as a solution in 1 ,2-dimethoxyethane (5ml). The reaction mixture is further stirred at 0°C for 30 minutes, then at ambient temperature for a 1 hour. After partitioning between 1 M hydrochloric acid and dichloromethane, the organic phase is separated, and the aqueous phase is extracted again with additional dichloromethane. All organics are combined then concentrated in vacuo to afford 4-[1 -(5-bromo-2-iodophenyl)methylidene]-2,2,5,5-tetramethyldihydrofuran-3-one (1 .18g) as a yellow gum.
Step 3: Preparation of 2-(5-Bromo-2-iodophenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000024_0001
To a solution of 4-[1 -(5-bromo-2-iodophenyl)methylidene]-2,2,5,5-tetramethyldihydrofuran-3- one (1 .18g, 2.73mmol) in methanol (50ml) at 35 °C is added 50% aqueous hydrogen peroxide solution (0.31 ml, 5.46mmol), followed immediately by 2M aqueous lithium hydroxide (0.34ml, 0.68mmol). This mixture is stirred at 35 °C for 3 hours, then quenched with saturated aqueous sodium metabisulfite and extracted with dichloromethane. The organic phase is separated, and the aqueous phase extracted again with dichloromethane. All organics are combined then evaporated under reduced pressure to afford 2-(5-bromo-2- iodophenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one as an oil which is used directly in the next step.
Step 4: Preparation of 4-(5-Bromo-2-iodophenyl)-2,2,6,6-tetramethylpyran
Figure imgf000024_0002
To crude 2-(5-bromo-2-iodophenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (from step 3) is added ice-cold concentrated sulphuric acid, and the reaction mixture is stirred at ambient temperature for 30 minutes. After dilution with distilled water the product is extracted with dichloromethane (x 2), then the combined organics are evaporated under reduced pressure. Purification by flash column chromatography (20% ethyl acetate in isohexane to ethyl acetate as eluant) affords 4-(5-bromo-2-iodophenyl)-2,2,6,6- tetramethylpyran-3,5-dione (0.225g) as a beige coloured solid. 1 H NMR (CDCI3): 57.80 (d, 1 H), 7.33 (m, 1 H), 7.25 (m, 1 H), 1 .66 (s, 3H), 1 .60 (s, 3H), 1 .55 (s, 3H), 1 .48 (s, 3H).
Example P5: Preparation of 4-(5-Bromo-2-trifluoromethoxyphenyl)-2,2,6,6-tetramethylpyran- 3,5-dione
Figure imgf000025_0001
Step 1 : Preparation of 4-[1 -(5-Bromo-2-trifluoromethoxyphenyl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000025_0002
To an ice-cold solution of 2,2,5,5-tetramethyldihydrofuran-3-one (2.84g, 20.00mmol) in anhydrous 1 ,2-dimethoxyethane (6ml) is added sodium methoxide (1 .19g, 22.04mmol) in one portion. After stirring at this temperature for 5 minutes a solution of 5-bromo-2- trifluoromethoxybenzaldehyde (4.84g, 18.00mmol) in 1 ,2-dimethoxyethane (6ml) is added dropwise over 10mins, followed by stirring at 0°C for a further 1 hour. After warming to room temperature the reaction mixture is diluted with ether and washed with 2M hydrochloric acid (x 2). Organic fractions are combined, dried over magnesium sulphate, filtered and the filtrate evaporated in vacuo to afford 4-[1 -(5-bromo-2-trifluoromethoxyphenyl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (7.06g) as an orange liquid.
Step 2: Preparation of 2-(5-Bromo-2-trifluoromethoxyphenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000026_0001
To a solution of 4-[1 -(5-bromo-2-trifluoromethoxyphenyl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (7.06g, 18.00mmol) in methanol (300ml) at 35°C is added 50% aqueous hydrogen peroxide (1 .80ml, 27.00mmol), immediately followed by 2M aqueous lithium hydroxide (1 .80ml, 3.60mmol). After stirring at this temperature for 1 hour the reaction mixture is allowed to cool, then quenched with 10% sodium metabisulfite solution (negative Kl-starch indicator test). The reaction mixture is extracted with diethyl ether (x 3), then the organic phase is further washed with saturated aqueous sodium bicarbonate (x 2) then brine. All organics are combined, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to afford 2-(5-bromo-2-trifluoromethoxyphenyl)-4,4,6,6-tetramethyl- 1 ,5-dioxaspiro[2.4]heptan-7-one (6.34g, 86%) as a yellow oil.
1 H NMR (CDCIs): δ 7.84 (s, 0.4H, isomer A), 7.56 (s, 0.6H, isomer B), 7.52 (d, 0.6H, isomer B), 7.48 (d, 0.4H, isomer A), 7.15 (d, 0.6H, isomer B), 7.07 (d, 0.4H, isomer A), 4.46 (m, 1 H, isomers A and B), 1.47 (s, 1 .2H, isomer A), 1 .39-1 .28 (m, 7.8H, isomers A and B), 1 .12 (s, 1 .2H, isomer A), 0.83 (s, 1.8H, isomer B) Preparation of 4-(5-Bromo-2-trifluoromethoxyphenyl)-2,2,6,6-tetramethylpyran-3,5-
Figure imgf000027_0001
To an ice-cold solution of concentrated sulphuric acid (10ml) is added a second solution of 2- (5-bromo-2-trifluoromethoxyphenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (6.34g, 15.00mmol) in 1 ,2-dichloroethane (10ml) dropwise over 5 minutes. This biphasic mixture is stirred vigorously for 2 hours at 0°C, then poured into ice-water, rinsing with a small amount of additional 1 ,2-dichloroethane/water. This mixture is then concentrated under vacuum to remove all organic solvents, until a free-flowing solid was produced. The solid is filtered, washed with water then isohexane, followed by drying under vacuum overnight. The solid is next redissolved in ethyl acetate, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to afford 4-(5-bromo-2-trifluoromethoxyphenyl)-2, 2,6,6- tetramethylpyran-3,5-dione (4.17g, 68%).
1 H NMR (CDCIs): 57.57 (dd, 1 H), 7.24 (d, 2H), 1.52 (br.s, 12H).
Example P6: Preparation of 4-(4-Bromo-4'-chlorobiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5- dione
Figure imgf000027_0002
Step 1 : Preparation of 4-Bromo-4'-chloro-biphenyl-3-carbaldehyde
Figure imgf000028_0001
To a solution of 4-bromo-4'-chloro-3-iodobiphenyl (4.80g, 0.012mol) (described in WO 2008/071405) in anhydrous diethyl ether/tetrahydrofuran (120ml, 1 :1 ratio) at -75°C is added isopropyl magnesium bromide (18.96ml, 15% solution in tetrahydrofuran) dropwise such as to maintain an internal temperature below -70°C. Once addition is complete the reaction mixture is stirred at -75°C for 2 hours, then warmed to -45°C. Anhydrous N,N- dimethylformamide (1 .71 g, 0.0184mol) is next added dropwise, maintaining temperature below - 40°C, followed by warming to room temperature and quenching with 2M hydrochloric acid (60ml). The reaction mixture is further diluted with diethyl ether, the two phases separated, and the aqueous phase extracted with additional diethyl ether. The combined organic extracts are washed with brine, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo. The crude product is purified by flash column chromatography (2% ethyl acetate in hexane eluant) to afford 4-bromo-4'-chloro-biphenyl-3-carbaldehyde (2.7g, 75%) as a white solid.
Step 2: Preparation of 4-[1 -(4-Bromo-4'-chlorobiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000028_0002
To an ice-cold solution of dihydro-2,2,5,5-tetramethylfuran-3-one (1 .37g (9.68mmol) in anhydrous 1 ,2-dimethoxyethane (10ml) is added sodium methoxide (0.575g, 10.60mmol) in one portion, followed by stirring at this temperature for 10 minutes. To this slurry is then added a second solution of 4-bromo-4'-chloro-biphenyl-3-carbaldehyde (2.60g, 8.80mmol) in 1 ,2-dimethoxyethane (10ml) dropwise. When addition is complete the reaction mixture is stirred at 0°C for a further 1 hour, then quenched with 2M hydrochloric acid (50ml). After stirring for an additional 1 hour the solution is diluted with diethyl ether, the two phases separated, and the aqueous phase further extracted with diethyl ether (x 2). The combined organics are further washed with brine, then dried over magnesium sulfate, filtered, and the filtrate concentrated in vacuo to afford 4-[1 -(4-bromo-4'-chlorobiphenyl-3-yl)-methylidene]- 2,2,5,5-tetramethyldihydrofuran-3-one (3.40g, 92%) as a yellow gum.
Step 3: Preparation of 2-(4-Bromo-4'-chlorobiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000029_0001
To a solution of 4-[1 -(4-bromo-4'-chlorobiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (3.40g, 9.03mmol) in methanol (140ml) at 35°C is added 50% aqueous hydrogen peroxide (1 .04ml, 15.60mmol), immediately followed by 2M aqueous lithium hydroxide (1 .15ml, 2.30mmol). The reaction mixture is stirred for a further 45 minutes at 35°C, then allowed to cool to room temperature and quenched with saturated sodium metabisulfite. After extracting the product into diethyl ether (x 3) the organic phase is separated, washed with additional water, then dried over magnesium sulfate. After filtration the filtrate is concentrated in vacuo to afford 2-(4-bromo-4'-chlorobiphenyl-3-yl)-4,4,6,6- tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (3.0g) as a yellow solid. This material was of sufficient purity to use directly in the next step. Step 4: Preparation of 4-(4-Bromo-4'-chlorobiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione
Figure imgf000030_0001
To an ice-cold solution of 2-(4-bromo-4'-chlorobiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one (3.00g, 6.90mmol) in dichloromethane (3.5ml) is added concentrated sulphuric acid (6.5ml) at such a rate as maintain an internal temperature below 5°C. After the addition is completed the reaction mixture is stirred for a further 20 minutes, after which distilled water (25ml) is added dropwise at 0°C. The reaction mixture is maintained at 5-10°C for 5 minutes, then concentrated in vacuo to remove organic solvents. The aqueous phase is filtered and the resulting solid triturated with hexane to afford 4-(4- bromo-4'-chlorobiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione (2.56g, 85%).
NMR (CDCIs): 57.75 (d, 1 H), 7.49 (d, 2H), 7.45 (dd, 1 H), 7.40 (s, 2H), 7.36 (s, 1 H), 5.56 (br.s, 1 H), 1 .65 (s, 3H), 1 .58 (s, 3H), 1.53 (s, 3H), 1.47 (s, 3H).
Example P7: Preparation of 4-(5-Bromo-2-fluorophenyl)-2,2,6,6-tetramethylpyran-3,5-dione
Figure imgf000030_0002
Step 1 : Preparation of 4-[1 -(5-Bromo-2-fluorophenyl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
To an ice-cold solution of dihydro-2,2,5,5-tetramethylfuran-3-one (4.56g, 32.10mmol) in anhydrous 1 ,2-dimethoxyethane (25ml) is added sodium methoxide (1 .91 g, 35.1 Omol) in one portion. After stirring at room temperature for 10 minutes a second solution of 5-bromo-2- fluorobenzaldehyde (5.93g, 29.10mmol) in anhydrous 1 ,2-dimethoxyethane (45ml) is added dropwise, followed by stirring at 0°C for a further 45 minutes. The reaction mixture is quenched with 2M hydrochloric acid (50ml), then diluted with diethyl ether and the two phases separated. The aqueous phase is further extracted with diethyl ether (x 2), then all organics are combined, washed with brine and dried over magnesium sulfate. After filtration the filtrate is concentrated in vacuo to afford 4-[1 -(5-bromo-2-fluorophenyl)-methylidene]- 2,2,5,5-tetramethyldihydrofuran-3-one (9.30g, 96%) as a yellow gum.
Step 2: Preparation of 2-(5-Bromo-2-fluorophenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000031_0002
To a solution of 4-[1 -(5-bromo-2-fluorophenyl)-methylidene]-2,2,5,5-tetramethyldihydrofuran- 3-one (9.30g, 29.00mmol) in methanol (280ml) at 35 °C is added 50% aqueous hydrogen peroxide (3.36ml, 50.40mmol), followed immediately by 2M aqueous lithium hydroxide (3.68ml, 7.36mmol). Stirring is continued at this temperature for 1 hour, then the reaction mixture is allowed to cool to room temperature, then quenched with saturated sodium metabisulfite (100ml) and extracted with ether (x 3). Organics are combined, dried over magnesium sulfate, then filtered and the filtrate concentrated in vacuo to afford 2-(5-bromo- 2-fluorophenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (6.60g, 68%) as a yellow gum.
Step 3: Preparation of 4-(5-Bromo-2-fluorophenyl)-2,2,6,6-tetramethylpyran-3,5-dione
Figure imgf000032_0001
To a solution of 2-(5-bromo-2-fluorophenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7- one (6.60g, 19.30mmol) in dichloromethane (8ml) is added a second ice-cold solution of concentrated sulphuric acid (13.8ml) dropwise, maintaining temperature below 5 °C. The reaction mixture is stirred for a further 30 minutes, then quenched with distilled water (50ml). After stirring for an additional 10 minutes the organics are removed in vacuo, and the resulting precipitate is filtered then triturated with water. After washing with hexanes the solid is dried to afford 4-(5-bromo-2-fluorophenyl)-2,2,6,6-tetramethylpyran-3,5-dione (4.30g, 65%).
1 H NMR (CDCIs): 57.5 (m, 1 H), 7.34 (m, 1 H), 7.06 (m, 1 H), 5.69 (br. s, 1 H), 1 .56 (d, 6H), 1 .52 (d, 6H).
Example P8: Preparation of 4-(4'-Chloro-4-cvclopropyl-2'-fluorobiphenyl-3-yl)-2,2,6,6- tetramethylpyran-3,5-dione
Figure imgf000033_0001
Step 1 : Preparation of 4'-chloro-2'-fluoro-4-hydroxybiphenyl-3-carbaldehyde
Figure imgf000033_0002
To a mixture of 5-bromosalicyaldehyde (30. Og, 0.15mol), 2-fluoro-4-chlorophenylboronic acid (30. Og, 0.17mol) and sodium carbonate (24. Og, 0.23mol) is added 1 ,2-dimethoxyethane (225ml) and distilled water (75ml), and the suspension is stirred under a nitrogen atmosphere. To this mixture is then added [1 ,1 - bis(diphenylphosphino)ferrocene]palladium(ll)chloride (4.5g, 7.5mmol), followed by heating at reflux overnight. After cooling to room temperature and dilution with distilled water (500ml) and dichloromethane (500ml), the two phases are separated, and the aqueous phase extracted again with dichloromethane (2 x 500ml). Organic fractions are combined, washed with brine (800ml) then dried over magnesium sulphate. The suspension is filtered and the filtrate is concentrated in vacuo. Then crude material is purified by flash column purification (5-10% ethyl acetate in isohexane eluant) to afford 4'-chloro-2'-fluoro-4-hydroxybiphenyl-3- carbaldehyde (33.61 g, 89%) as a pale yellow solid.
Step 2: Preparation of Trifluoromethanesulfonic acid 4'-chloro-2'-fluoro-3-formylbiphenyl-4-yl ester
Figure imgf000034_0001
To an ice-cold mixture of 4'-chloro-2'-fluoro-4-hydroxybiphenyl-3-carbaldehyde (33.60g, 0.13mol) and pyridine (31.0ml, 0.36mol) in anhydrous dichloromethane (700ml) is added triflic anhydride (27.0ml, 0.16mmol) dropwise over 30 minutes, maintaining temperature below 10°C. The reaction mixture is then allowed to warm to room temperature, followed by stirring overnight. After dilution with distilled water (500ml) and dichloromethane (500ml), the two layers are separated and the aqueous phase is extracted again with dichloromethane (2 x 500ml). Organic fractions are combined, washed with brine (800ml), then dried over magnesium sulfate and concentrated in vacuo. The crude product is purified by flash column chromatography (10% ethyl acetate in hexane eluant) to afford trifluoromethanesulfonic acid 4'-chloro-2'-fluoro-3-formylbiphenyl-4-yl ester as a yellow oil.
Ste 3: Preparation of 4'-Chloro-4-cyclopropyl-2'-fluorobiphenyl-3-carbaldehyde
Figure imgf000034_0002
To a mixture of trifluoromethanesulfonic acid 4'-chloro-2'-fluoro-3-formylbiphenyl-4-yl ester (30. Og, 0.078mol), cyclopropyl boronic acid (8.80g, O.I Omol), potassium phosphate (58.40g, 0.28mol) and sodium bromide (8.0g, 0.078mol) is added toluene (300ml) then distilled water (30ml) under a nitrogen atmosphere. To this mixture is then added tetrakis(triphenylphosphine) palladium (9.60g, 8.40mmol) in one portion, and the mixture is then heated at 100°C overnight. After cooling to room temperature the mixture is diluted with distilled water (500ml) and ethyl acetate (500ml), and the two layers are separated and the aqueous phase extracted again with ethyl acetate (2 x 500ml). Organic fractions are combined, washed with distilled water (1 L) then brine (1 L), and then dried over magnesium sulphate. The suspension is filtered and the filtrate concentrated in vacuo. The crude product is purified by flash column chromatography on silica gel, then additionally by flash column chromatography on basic alumina (10% ethyl acetate in hexane as eluant) to afford 4'-chloro- 4-cyclopropyl-2'-fluoro-biphenyl-3-carbaldehyde (7.6g, 36%).
Step 4: 4-[1 -(4'-Chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000035_0001
To an ice-cold solution of dihydro-2,2,5,5-tetramethylfuran-3-one (8.40g, 0.059mol) in anhydrous 1 ,2-dimethoxyethane (75ml) is added sodium methoxide (3.60g, 0.066mol) in one portion, and the mixture is stirred at this temperature for 30 minutes. A solution of 4'-chloro-4- cyclopropyl-2'-fluorobiphenyl-3-carbaldehyde (14.80g, 0.054mmol) is then added dropwise over 20 minutes, maintaining temperature below 10°C. The reaction mixture is stirred at this temperature for 1 hour, then allowed to warm to room temperature before diluting with diethyl ether and distilled water. The two phases are separated, and the aqueous phase is extracted again with diethyl ether (x 2). Organic fractions are combined, washed with brine, then dried over magnesium sulfate. The suspension is filtered and the filtrate concentrated in vacuo to afford 4-[1 -(4'-chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (19.80g) which is of sufficient purity to use directly in the next step.
Step 5: 2-(4'-Chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5-dioxa- spiro[2.4]heptan-7-one
Figure imgf000036_0001
To a solution of 4-[1 -(4'-chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)methylidene]-2, 2,5,5- tetramethyldihydrofuran-3-one (19.80g, 0.050mol) in methanol (830ml) at 35°C is added 50% aqueous hydrogen peroxide (5.00ml, 0.075mmol), followed immediately by 2M lithium hydroxide (5.00ml, 0.01 mol) solution. The mixture is stirred at this temperature for a further 2 hours, then allowed to cool to room temperature. Then reaction mixture is quenched with 10% sodium metabisulfite (negative Kl-starch indicator test) then diluted with diethyl ether. Most of the methanol is removed under vacuum, and the crude mixture is partitioned between distilled water and diethyl ether. The aqueous phase is further extracted with diethyl ether (x 2), then all organics are combined and washed with saturated sodium bicarbonate (x 2) then brine. After anhydrousing over magnesium sulfate the suspension is filtered and the filtrate concentrated in vacuo to afford 2-(4'-chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)- 4,4,6,6-tetramethyl-1 ,5-dioxa-spiro[2.4]heptan-7-one (18.2g) as an orange foam. This material is of sufficient purity to use directly in the next step without further purification.
1 H NMR (CDCIs): δ 7.48 (s, 1 H), 7.39 (d, 1 H), 7.32 (t, 1 H), 7.24-7.12 (m, 2H), 7.00 (d, 1 H), 4.76 (s, 1 H), 1 .84-1 .76 (m, 1 H), 1 .42-1 .26 (m, 9H), 1 .1 1 -0.96 (m, 2H), 0.88-0.79 (m, 4H), 0.78-0.71 (m, 1 H).
Step 6: Preparation of 4-(4'-Chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)-2,2,6,6- tetramethylpyran-3,5-dione
Figure imgf000037_0001
To a mixture of 2-(4'-chloro-4-cyclopropyl-2'-fluorobiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one (18.20g, 0.044mol) and ytterbium triflate (2.40g, 4.40mmol) is added a solution of 5M lithium perchlorate (prepared from 46ml diethyl ether and 24.40g lithium perchlorate). The resulting suspension is stirred at room temperature for 3 days, then is diluted with diethyl ether (85ml) and additional ytterbium triflate (7.80g, 0.014mol) is added. After stirring at room temperature for a further 3 days additional ytterbium triflate (13.63g, 0.025mol) is added, and the reaction mixture is stirred for 1 1 days. Finally, extra lithium perchlorate (24.40g, 0.23mol) is added in one portion, and the mixture is heated at 27°C (internal temperature) for 1 day. The reaction mixture is partitioned between diethyl ether and distilled water, the two phases separated, and the aqueous phase is extracted with diethyl ether (x 2). The organic fractions are combined, washed with brine then dried over magnesium sulphate. The suspension is filtered and the filtrate concentrated in vacuo. The crude material purified by flash column chromatography (10% ethyl acetate in hexanes as eluant) to afford an oil which is triturated with hexanes to afford 4-(4'-chloro-4-cyclopropyl-2'- fluorobiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione (4.78g) as a white solid.
1 H NMR (CDCIs): δ 7.47 (d, 1 H), 7.38 (t, 1 H), 7.23 (s, 1 H), 7.21 -7.12 (m, 3H), 5.68 (s, 1 H), 1 .75 (m, 1 H), 1 .62 (s, 6H), 1 .49 (s, 6H), 0.92-0.82 (m, 2H), 0.81 -0.75 (m, 1 H), 0.61 -0.53 (m, 1 H)
Example P9: Preparation of 4-(2',4'-Dichloro-4-cvclopropylbiphenyl-3-yl)-2,2,6,6- tetramethylpyran-3,5-dione
Figure imgf000038_0001
Step 1 : Preparation of 2',4'-Dichloro-4-hydroxybiphenyl-3-carbaldehyde
Figure imgf000038_0002
To a mixture of 5-bromosalicyaldehyde (30. Og, 0.15mol), 2,4-dichlorophenylboronic acid (32. Og, 0.17mol) and sodium carbonate (24. Og, 0.23mol) is added 1 ,2-dimethoxyethane (225ml) and distilled water (75ml), and the suspension is stirred under a nitrogen atmosphere. To this mixture is then added [1 ,1 - bis(diphenylphosphino)ferrocene]palladium(ll)chloride (4.5g, 7.5mmol), followed by heating at reflux overnight. After cooling to room temperature and dilution with distilled water (500ml) and dichloromethane (500ml), the two phases are separated, and the aqueous phase extracted again with dichloromethane (2 x 500ml). Organic fractions are combined, washed with brine (800ml) then dried over magnesium sulphate. The suspension is filtered and the filtrate concentrated in vacuo. Then crude material is finally purified by flash column purification (10% ethyl acetate in isohexane eluant) to afford 2',4'-dichloro-4- hydroxybiphenyl-3-carbaldehyde (32.73g, 82%) as a pale yellow solid.
Step 2: Preparation of Trifluoromethanesulfonic acid 2',4'-dichloro-3-formylbiphenyl-4-yl ester
Figure imgf000039_0001
To an ice-cold mixture of 2',4'-dichloro-4-hydroxybiphenyl-3-carbaldehyde (31.70g, 0.12mol) and pyridine (25.0ml, 0.29mol) in anhydrous dichloromethane (650ml) is added triflic anhydride (22.0ml, 0.13mmol) dropwise over 30 minutes, maintaining temperature between 0-10°C. The reaction mixture is then allowed to warm to room temperature, followed by stirring overnight. After dilution with distilled water (500ml) and dichloromethane (300ml), the two layers are separated and the organic phase is further washed with saturated aqueous copper sulfate solution (3 x 500ml), water (500ml), then brine (500ml). After anhydrousing over magnesium sulfate the solvent is removed under vacuum and the crude product is purified by flash column chromatography (10% ethyl acetate in hexane eluant) to afford trifluoromethanesulfonic acid 2',4'-dichloro-3-formylbiphenyl-4-yl ester as an orange oil.
Ste 3: Preparation of 2',4'-Dichloro-4-cyclopropylbiphenyl-3-carbaldehyde
Figure imgf000039_0002
To a mixture of trifluoromethanesulfonic acid 2',4'-dichloro-3-formylbiphenyl-4-yl ester (30. Og, 0.075mol), cyclopropyl boronic acid (8.50g, 0.097mol), potassium phosphate (56.30g, 0.27mol) and sodium bromide (7.7g, 0.075mol) is added toluene (300ml) then distilled water (30ml) under a nitrogen atmosphere. To this mixture is then added tetrakis(triphenylphosphine) palladium (9.30g, 0.0081 mol) in one portion, and the mixture is then heated at 100°C overnight. After cooling to room temperature the mixture is diluted with distilled water (500ml) and ethyl acetate (500ml), and the two layers are separated. The aqueous phase is extracted again with ethyl acetate (2 x 500ml), then all organic fractions are combined, then washed with distilled water (1 L) then brine (1 L). After drying over magnesium sulfate the suspension is filtered and the filtrate is concentrated in vacuo. The crude product is purified by flash column chromatography on silica gel (2-10% ethyl acetate in hexanes as eluant), then additionally by flash column chromatography on basic alumina (10% ethyl acetate in hexane as eluant) to afford 2',4'-dichloro-4-cyclopropylbiphenyl-3- carbaldehyde (1 1 .7g, 54%).
Step 4: 4-[1 -(2',4'-Dichloro-4-cyclopropylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000040_0001
To an ice-cold solution of dihydro-2,2,5,5-tetramethylfuran-3-one (15.70g, 0.1 1 mol) in anhydrous 1 ,2-dimethoxyethane (285ml) is added sodium methoxide (6.50g, 0.12mol) in one portion, and the mixture is stirred at this temperature for 30 minutes. A solution of 2', 4'- dichloro-4-cyclopropylbiphenyl-3-carbaldehyde (13.70g, 0.047mmol) is then added dropwise over 20 minutes, maintaining temperature below 10°C. The reaction mixture is stirred at this temperature for 2 hours, then allowed to warm to room temperature before diluting with diethyl ether and distilled water. The two phases are separated, and the aqueous phase is extracted again with diethyl ether (x 2). Organic fractions are combined, washed with brine, then dried over magnesium sulphate. The suspension is filtered and filtrate concentrated in vacuo. The aqueous phase is further acidified with 2M hydrochloric acid then extracted again with diethyl ether (x 2), dried over magnesium sulfate and concentrated in vacuo. All organics are combined, then diluted with toluene and azeotroped (x 4) to afford 4-[1 -(2',4'-dichloro-4- cyclopropylbiphenyl-3-yl)-methylidene]-2,2,5,5-tetramethyldihydrofuran-3-one (20. Og) which is of sufficient purity to use directly in the next step. Step 5: 2-(2',4'-Dichloro-4-cyclopropylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5-dioxa- spiro[2.4]heptan-7-one
Figure imgf000041_0001
To a solution of 4-[1 -(2',4'-dichloro-4-cyclopropylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (20.0g, 0.048mol) in methanol (800ml) at 35°C is added 50% aqueous hydrogen peroxide (4.80ml, 0.072mmol), followed immediately by 2M lithium hydroxide (4.80ml, 9.60mmol) solution. The mixture is stirred at this temperature for a further 2 hours, then allowed to cool to room temperature. Then reaction mixture is quenched with 10% sodium metabisulfite (negative Kl-starch indicator test) then diluted with diethyl ether. Most of the methanol is removed under vacuum, and the crude mixture is partitioned between distilled water and diethyl ether. The aqueous phase is further extracted with diethyl ether (x 2), then all organics are combined and washed with saturated sodium bicarbonate (x 2) then brine. After drying over magnesium sulfate the suspension is filtered and the filtrate concentrated in vacuo to afford 2-(2',4'-dichloro-4-cyclopropylbiphenyl-3-yl)-4,4,6,6- tetramethyl-1 ,5-dioxa-spiro[2.4]heptan-7-one (17.80g) as an orange foam. This material is of sufficient purity to use directly in the next step without further purification.
1 H NMR (CDCIs): δ 7.49 (s, 1 H), 7.37 (s, 1 H), 7.37-7.25 (m, 2H), 7.20 (d, 1 H), 6.99 (d, 1 H), 4.75 (s, 1 H), 1 .80 (m, 1 H), 1 .40-1 .28 (m, 9H), 1 .10-0.98 (m, 2H), 0.90-0.80 (m, 4H), 0.75- 0.80 (m, 1 H).
Step 6: Preparation of 4-(2',4'-Dichloro-4-cyclopropylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran- 3,5-dione
Figure imgf000042_0001
To a mixture of 2-(2',4'-dichloro-4-cyclopropylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5-dioxa- spiro[2.4]heptan-7-one (17.80g, 0.041 mol) and ytterbium triflate (2.20g, 4.41 mmol) is added a solution of 5M lithium perchlorate (prepared from 42ml diethyl ether and 22.30g lithium perchlorate). The resulting suspension is stirred at room temperature for 17 days, at which stage further diethyl ether (42ml), lithium perchlorate (22.3g, 0.21 mol) and ytterbium triflate (19.8g, 0.035mol) is added. The reaction mixture is then heated at 27°C (internal temperature) for 1 day, followed by partitioning between diethyl ether and distilled water. The two phases are separated, the aqueous phase is extracted with diethyl ether (x 2), and then all organic fractions are combined, washed with brine then dried over magnesium sulphate. The suspension is filtered and the filtrate is concentrated in vacuo. The crude material is purified by flash column chromatography (ethyl acetate/hexane eluant) to give an oil which is triturated with hexanes to afford 4-(2',4'-dichloro-4-cyclopropylbiphenyl-3-yl)-2,2,6,6- tetramethylpyran-3,5-dione (2.80g) as a white solid.
1 H NMR (CDCIs): δ 7.48 (s, 1 H), 7.38 (dd, 1 H), 7.29 (s, 2H), 7.16-7.1 1 (m, 2H), 5.69 (s, 1 H), 1 .76 (m, 1 H), 1 .61 (d, 6H), 1.49 (d, 6H), 0.92-0.86 (m, 2H), 0.82-0.76 (m, 1 H), 0.62-0.54 (m, 1 H).
Example P10 : Preparation of 4-(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-
3,5-dione
Figure imgf000042_0002
Step 1 : Preparation of 2',4'-Dichloro-4-ethylbiphenyl-3-carbaldehyde
Figure imgf000043_0001
A suspension of 5-bromo-2-ethylbenzaldehyde (1 .0g, 4.7mmol), 2,4-dichlorophenyl boronic acid (1 .34g, 7.0mmol) and sodium carbonate (0.99g, 7.98mmol) in a mixed solvent system of 1 ,2-dimethoxyethane (12ml) and distilled water (4ml) is stirred under a nitrogen atmosphere, then flushed with nitrogen (x 2). [1 ,1 '-Bis(diphenylphosphino)ferrocene]palladium(ll)chloride (1 .15g, 1 .41 mmol) is then added in one portion and the suspension is again flushed with nitrogen, then heated at reflux overnight. After cooling to room temperature the reaction mixture is diluted with distilled water (10ml) and extracted with dichloromethane (10ml). The aqueous phase is extracted again with dichloromethane (x 2), and the combined organic fractions are finally washed with brine then dried over magnesium sulfate. The crude product is purified by flash column chromatography (isohexane to 75:25 isohexane/ethyl acetate ratio eluant) to afford 2',4'-dichloro-4-ethylbiphenyl-3-carbaldehyde as a yellow oil.
Step 2: Preparation of 4-[1 -(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000043_0002
To an ice-cold solution of 2,2,5, 5-tetramethyldihydrofuran-3-one (1 .15g, 0.0081 mol) in 1 ,2- dimethoxyethane (2ml) is added sodium methoxide (0.481 g, 0.0089mol) in one portion. The reaction mixture is then stirred for 5 minutes at this temperature, followed by the addition of a second solution of 2',4'-dichloro-4-ethylbiphenyl-3-carbaldehyde (2.02g, 0.0072mol) in 1 ,2- dimethoxyethane (2.7ml). After stirring for an additional 2 hours at 0°C the reaction mixture is allowed to stand at room temperature overnight. The crude solution is poured into 2M hydrochloric acid and extracted with ether (x 3). The organics are combined, washed with brine, dried over magnesium sulfate and concentrated in vacuo. The residue is purified by flash column chromatography (5% ethyl acetate in isohexane to 25% ethyl acetate in isohexane) to afford 4-[1 -(2',4'-dichloro-4-ethylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one as a yellow gum.
Step 3A: Preparation of 2-(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000044_0001
To a solution of 4-[1 -(2',4'-dichloro-4-ethylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (2.04g, 0.0051 mol) in methanol (24ml) at 55°C is added hydrogen peroxide solution (0.43ml, 0.0076mmol, 50% wt solution), followed immediately by aqueous lithium hydroxide (0.25ml, 0.0005mol). The reaction mixture is heated at this temperature for 30 minutes, then is rapidly cooled to room temperature and quenched with saturated sodium thiosulphate. The crude product is extracted with diethyl ether (x 3), washed with saturated sodium bicarbonate, then dried over magnesium sulfate. The residue is purified by flash column chromatography (5% ethyl acetate in isohexane to 25% ethyl acetate in isohexane) to afford 2-(2',4'-dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one as a yellow gum.
Step 3B: Preparation of 2-(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000045_0001
To a solution of 4-[1 -(2',4'-dichloro-4-ethylbiphenyl-3-yl)-methylidene]-2,2,5,5- tetramethyldihydrofuran-3-one (0.500g, 1.24mmol) in toluene (3.7ml) is added aqueous sodium hyperchlorite solution (3.30g, 6.20mmol, 14% active chlorine) and tetrabutylammonium hydrogen sulfate (0.013g, 0.04mmol), and the biphasic mixture is then stirred at 50°C for 4 hours. The reaction mixture is then dilluted with additional toluene, the phases separated, and the organic phase washed again with distilled water (x 2). The organic phase is dried over sodium sulfate then concentrated in vacuo to afford 2-(2',4'- dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one as a white solid.
Step 4A: Preparation of 4-(2',4'-Dichloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5- dione
Figure imgf000045_0002
To an ice-cold solution of concentrated sulphuric acid (6ml) is added a second solution of 2- (2',4'-dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (1 .90g, 0.0045mol) in 1 ,2-dichloroethane (6ml) dropwise over 5 mins. This biphasic mixture is stirred vigorously for 2 hours at 0°C, then is poured into ice and extracted with diethyl ether. All organics are combined, washed with brine, dried over magnesium sulfate then concentrated in vacuo. The crude product is purified by flash column chromatography (5% ethyl acetate in isohexane to 25% ethyl acetate in isohexane) to afford 4-(2',4'-dichloro-4- ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione as a yellow gum.
1 H NMR (CDCIs): δ 7.48 (d, 1 H), 7.43 (m, 2H), 7.30 (m, 2H), 7.13 (d, 1 H), 5.71 (br. s, 1 H), 2.55-2.44 (m, 2H), 1 .62 (s, 6H), 1 .49 (app. d, 6H), 1.17 (t, 3H).
Step 4B: Preparation of 4-(2'!4'-Dichloro-4-ethylbiphenyl-3-yl)-2!2!6!6-tetramethylpyran-3,5- dione
Figure imgf000046_0001
To a solution of 2-(2'!4'-dichloro-4-ethylbiphenyl-3-yl)-4!4!6!6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one (0.0418g, O.I Ommol) in toluene (0.3ml) is added p- toluenesulfonic acid monohydrate (0.019g, O.I Ommol). The mixture is then heated at 150°C for 1 hour, after which it is allowed to cool to room temperature. The reaction mixture is poured into distilled water, dried over sodium sulfate, then concentrated in vacuo to afford 4- (2',4'-dichloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione.
Example P1 1 : Preparation of 4-(5-Bromo-2-difluoromethoxyphenyl)-2,2,6,6-tetramethylpyran- 3,5-dione
Figure imgf000047_0001
Step 1 : Preparation of 5-Bromo-2-difluoromethoxybenzaldehyde
Figure imgf000047_0002
To a suspension of 5-bromosalicylaldehyde (7.60g, 0.038mol) and cesium carbonate (17.30g, 0.053mol) in anhydrous Λ ,/V-dimethylformamide (55ml) is added sodium chlorodifluoroacetate (13.30g, 0.087mol) followed by distilled water (10ml). The reaction mixture is heated at 100°C for 6 hours (large pieces of solid are broken-up with a spatula), then allowed to cool to room temperature and is quenched with concentrated hydrochloric acid (15ml). After stirring for a further 2 hours the reaction mixture is diluted with distilled water and extracted with ethyl acetate (x 2). Organic fractions are combined, washed with 2M aqueous sodium hydroxide, brine, then dried over magnesium sulfate. The suspension is filtered and the filtrate concentrated in vacuo to afford 5-bromo-2- trifluoromethoxybenzaldehyde (5.66g) of sufficient purity to use directly in the next step.
Step 2: Preparation of 4-[1 -(5-Bromo-2-difluoromethoxyphenyl)methylidene]-2, 2,5,5- tetramethyldihydrofuran-3-one
Figure imgf000048_0001
To an ice-cold solution of 2,2,5,5-tetramethyldihydrofuran-3-one (3.60g, 0.025mol) in anhydrous 1 ,2-dimethoxyethane (8 ml) is added sodium methoxide (1 .51 g, 0.028mol) in one portion. After stirring at this temperature for 5 minutes a solution of 5-bromo-2- difluoromethoxy-benzaldehyde (5.66g, 0.023mol) in 1 ,2-dimethoxyethane (8 ml) is added dropwise over 10mins, followed by stirring at 0°C for a further 1 hour. After warming to room temperature the reaction mixture is diluted with ether and washed with 2M hydrochloric acid (x2). Organic fractions are combined, dried over magnesium sulfate and evaporated in vacuo to afford 4-[1 -(5-bromo-2-difluoromethoxyphenyl)methylidene]-2, 2,5,5- tetramethyldihydrofuran-3-one (8.89g) as an orange oil.
Step 3: Preparation of 2-(5-Bromo-2-difluoromethoxyphenyl)-4,4,6,6-tetramethyl-1 ,5- dioxaspiro[2.4]heptan-7-one
Figure imgf000048_0002
To a solution of 4-[1 -(5-bromo-2-difluoromethoxyphenyl)methylidene]-2, 2,5,5- tetramethyldihydrofuran-3-one (8.89g, 0.023mol) in methanol (380ml) at 35°C is added 50% aqueous hydrogen peroxide (2.30ml, 0.034mol), immediately followed by 2M aqueous lithium hydroxide (2.30ml, 0.0046mmol). After stirring at this temperature for 1 hour the reaction mixture is allowed to cool, then quenched with 10% sodium metabisulfite solution (negative Kl-starch indicator test). The reaction mixture is extracted with diethyl ether (x 3), then the organic phase is further washed with saturated aqueous sodium bicarbonate (x 2) then brine. All organics are combined, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to afford 2-(5-bromo-2-difluoromethoxyphenyl)-4,4,6,6-tetramethyl- 1 ,5-dioxaspiro[2.4]heptan-7-one (7.22g) a yellow gum.
Step 4: Preparation of 4-(5-Bromo-2-difluoromethoxyphenyl)-2,2,6,6-tetramethylpyran-3,5- dione
Figure imgf000049_0001
To an ice-cold solution of concentrated sulphuric acid (12ml) is added a second solution of 2- (5-bromo-2-difluoromethoxyphenyl)-4,4,6,6-tetramethyl-1 ,5-dioxaspiro[2.4]heptan-7-one (7.22g, 18.00mmol) in 1 ,2-dichloroethane (12ml) dropwise over 5 minutes. This biphasic mixture is stirred vigorously for 2 hours at 0°C, then allowed to stand at room temperature overnight. The reaction mixture is poured into ice-water, rinsing with a small amount of additional 1 ,2-dichloroethane/water, then concentrated under vacuum to remove all organic solvents. The crude product is next extracted into ethyl acetate (x 3), than all organics are combined, washed with brine, and dried over magnesium sulfate. The suspension is filtered and the filtrate is concentrated in vacuo then purified by flash column chromatography (10% to 25% ethyl acetate in hexane as eluant) to give an oil which is triturated with hexanes to afford 4-(5-bromo-2-difluoromethoxyphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (2.08g) as a white solid.
1 H NMR (CDCIs): δ 7.54 (dd, 0.75H, isomer A), 7.51 (dd, 0.25H, isomer B), 7.37 (d, 0.75H, isomer A), 7.32 (d, 0.25H, isomer B), 7.15 (d, 0.75H, isomer A), 7.06 (d, 0.25H, isomer), 6.32 (t, 0.75H, isomer A), 6.29 (t, 0.25H, isomer B) 1 H), 5.86 (s, 0.75H, isomer A), 5.28 (s, 0.25H, isomer A), 1 .58-1 .44 (m, 12H, isomers A and B).

Claims

What is claimed is:
1. Compounds of formu
Figure imgf000051_0001
wherein
R1 is halogen, d-C4alkyl, Ci-C4haloalkyl, C3-C6cycloalkyl, C C4alkoxy, Ci-C4haloalkoxy, C C4alkylthio, Ci-C4alkylsulfinyl, Ci-C4alkylsulfonyl,
R2 is hydrogen, halogen, methylsulfonyloxy, CrC4haloalkylsulfonyloxy, p-tolylsulfonyloxy, optionally substituted aryl or optionally substituted heteroaryl;
r is 0, 1 , 2 or 3;
R3 if r is 1 , is C C6alkyl, C C6haloalkyl, C C6alkoxy, C C6haloalkoxy, C C6alkylthio, C C6alkylsulfinyl, CrC6alkylsulfonyl, cyano or nitro; or the substituents R3, if r is 2 or 3, independently of each other, are CrC6alkyl, CrC6haloalkyl, Ci-C6alkoxy, CrC6haloalkoxy, CrC6alkylthio, CrC6alkylsulfinyl, CrC6alkylsulfonyl, cyano or nitro;
Y is O, S, SO, S02 or CO,
R4, R5, R6 and R7, independently of each other, are hydrogen, Ci-C4alkyl, Ci-C4haloalkyl, C C4alkoxyCi-C4alkyl, Ci-C4alkylthioCi-C4alkyl, Ci-C4alkylsulfinylCrC4alkyl, C C4alkylsulfonylCrC4alkyl, cyclopropyl or cyclopropyl substituted by C or C2alkyl, C or C2haloalkyl or halogen; cyclobutyl or cyclobutyl substituted by C or C2alkyl; oxetanyl or oxetanyl substituted by C or C2alkyl; C5-C7cycloalkyl or C5-C cycloalkyl substituted by C or C2alkyl or C or C2haloalkyl, where a methylene group of the cycloalkyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; C4- C cycloalkenyl or C4-C cycloalkenyl substituted by C or C2alkyl or C or C2haloalkyl, where a methylene group of the cycloalkenyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; cyclopropylCrC5alkyl or cyclopropylCrC5alkyl substituted by C or C2alkyl, C or C2haloalkyl or halogen; cyclobutylCrC5alkyl or cyclobutylCrC5alkyl substituted by C or C2alkyl; oxetanylCrC5alkyl or oxetanylCrC5alkyl substituted by C or C2alkyl; C5-C cycloalkylCrC5alkyl or C5-C cycloalkylCi-C5alkyl substituted by C or C2alkyl or C or C2haloalkyl, where a methylene group of the cycloalkyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; C4- C7cycloalkenylCi-C5 alkyl or C4-C cycloalkenylCi-C5alkyl which is substituted by d- or C2alkyl or C or C2haloalkyl, where a methylene group of the cycloalkenyl moiety is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; phenyl or phenyl substituted by Ci-C4alkyl, C C4alkoxy, Ci-C4haloalkyl, halogen, nitro, cyano, C C4alkylthio, Ci-C4alkylsulfinyl, Ci-C4alkylsulfonyl or Ci-C4alkylcarbonyl; benzyl or benzyl substituted by Ci-C4alkyl, C C4alkoxy, Ci-C4haloalkyl, halogen, nitro, cyano, Ci-C4alkylthio, Ci-C4alkylsulfinyl, Ci-C4alkylsulfonyl or Ci-C4alkylcarbonyl; heteroaryl or heteroaryl substituted by Ci-C4alkyl, C C4alkoxy, Ci-C4haloalkyl, halogen, nitro, cyano, Ci-C4alkylthio, Ci-C4alkylsulfinyl, Ci-C4alkylsulfonyl or Ci-C4alkylcarbonyl; or
R4 and R5, or R6 and R7, are joined to form a 5-7 membered saturated or unsaturated ring in which a methylene group is optionally replaced by an oxygen or sulfur atom, or a 5-7 membered saturated or unsaturated ring substituted by C or C2alkyl, where a methylene group of the ring is optionally replaced by an oxygen or sulfur atom; or
R4 and R7 are joined to form a 5-7 membered saturated or unsaturated ring unsubstituted or substituted by d- or C2alkyl, d- or C2alkoxy, Ci-or C2alkoxyCi- or C2alkyl, hydroxy, halogen, phenyl or phenyl substituted by Ci-C4alkyl, Ci-C4alkoxy, Ci-C4haloalkyl, halogen, nitro, cyano, Ci-C4alkylthio, Ci-C4alkylsulfinyl, Ci-C4alkylsulfonyl or Ci-C4alkylcarbonyl; heteroaryl or heteroaryl substituted by Ci-C4alkyl, Ci-C4alkoxy, Ci-C4haloalkyl, halogen, nitro, cyano, Ci-C4alkylthio, Ci-C4alkylsulfinyl, Ci-C4alkylsulfonyl or Ci-C4alkylcarbonyl.
2. A compound according to claim 1 , wherein R1 is halogen, Ci-C4alkyl, Ci-C4haloalkyl, C3- C6cycloalkyl or Ci-C4-haloalkoxy.
3. A compound according to claim 1 , wherein R2 is halogen, aryl or heteroaryl; or aryl or heteroaryl both substituted by halogen, Ci-C4alkyl, Ci-C4haloalkyl, C2-C4alkenyl, C2- C4haloalkenyl, C2-C4alkynyl, C C4alkoxy, Ci-C4haloalkoxy, phenoxy, Ci-C4alkylthio, C C4alkylsulfinyl, Ci-C4alkylsulfonyl, Ci-C4haloalkylthio, Ci-C4haloalkylsulfinyl, C C4haloalkylsulfonyl, C3-C6cycloalkyl, Ci-C4alkylsulfonyloxy, Ci-C4haloalkylsulfonyloxy, C C4alkoxyCi-C4alkyl, Ci-C4alkylthioCi-C4alkyl, Ci-C4alkylsulfinylCrC4alkyl, C C4alkylsulfonylCrC4alkyl, nitro, cyano, thiocyanato, hydroxy, amino, Ci-C6alkylamino, C C6dialkylamino, C3-C6cycloalkylamino, morpholino, thiomorpholino, Ci-C6alkylcarbonylamino, Ci-C6alkoxycarbonylamino, C3-C6 alkenyloxycarbonylamino, C3-C6 alkynyloxycarbonylamino, Ci-C6 alkylaminocarbonylamino, di(Ci-6alkyl)aminocarbonylamino, formyl, CrC6alkyl- carbonyl, C2-C6alkenylcarbonyl, C2-C6alkynylcarbonyl, carboxy, CrC6alkoxycarbonyl, C3- C6alkenyloxycarbonyl, C3-C6alkynyloxycarbonyl, carboxamido, Ci-C6alkylaminocarbonyl, di(Ci-C6alkyl)aminocarbonyl, CrC6alkylcarbonyloxy, Ci-C6alkylaminocarbonyloxy, di(C C6alkyl)aminocarbonyloxy or Ci-C6alkylthiocarbonylamino.
4. A compound according to claim 3, wherein R2 in the compounds of formula I is halogen, aryl or heteroaryl; or aryl or heteroaryl both substituted by halogen, d-C4alkyl, C C4haloalkyl, phenoxy, C2-C4alkenyl, C2-C4haloalkenyl, C2-C4alkynyl, C C4alkoxy, C C4haloalkoxy, Ci-C4alkylthio, Ci-C4alkylsulfinyl, Ci-C4alkylsulfonyl, Ci-C4haloalkylthio, C C4haloalkylsulfinyl, Ci-C4haloalkylsulfonyl, nitro or cyano.
5. A compound according to claim 4, wherein R2 is phenyl, thienyl, furyl, pyrrolyl, isoxazolyl, oxazolyl, isothiazolyl, thiazolyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyrazinyl, triazinyl, pyridazinyl, oxadiazolyl and thiadiazolyl, and N-oxides and salts thereof, where these rings are unsubstituted or substituted by halogen, Ci-C4alkyl, Ci-C4haloalkyl, C2- C4alkenyl, C2-C4haloalkenyl, C2-C4alkynyl, Ci-C4alkoxy, Ci-C4haloalkoxy, Ci-C4alkylthio, d- C4alkylsulfinyl, Ci-C4alkylsulfonyl, Ci-C4haloalkylthio, Ci-C4haloalkylsulfinyl, d- C4haloalkylsulfonyl, nitro or cyano.
6. A compound according to claim 5, wherein R2 is phenyl or pyridyl or phenyl or pyridyl, both substituted by halogen, nitro, cyano, Ci-C2alkyl, Ci-C2haloalkyl, C C2alkoxy or C C2haloalkoxy.
7. A compound according to claim 6, wherein R2 is phenyl substituted at the para-position by halogen and is optionally further substituted by halogen, nitro, Ci-C2alkyl, Ci-C2haloalkyl, C C2alkoxy or Ci-C2haloalkoxy.
8. A compound according to claim 1 , wherein R3 is hydrogen or CrC6alkyl.
9. A compound according to claim 1 , wherein R3, if r is 1 , is CrC3alkyl.
10. A compound according to claim 1 , wherein R4, R5, R6 and R7, independently of each other, are hydrogen, Ci-C4alkyl, Ci-C4haloalkyl, Ci-C4alkoxyCi-C4 alkyl, Ci-C4alkylthioCi- C4alkyl, Ci-C4alkylsulfinylCrC4alkyl, Ci-C4alkylsulfonylCrC4alkyl; C5-C7cycloalkyl or C5- C cycloalkyl substituted by C or C2alkyl or C or C2haloalkyl and in which a methylene group is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group; C5- C7cycloalkylCi-C5alkyl or C5-C cycloalkylCi-C5alkyl substituted by d-C2alkyl or C or C2haloalkyl and in which a methylene group is optionally replaced by an oxygen or sulfur atom or a sulfinyl or sulfonyl group.
1 1. A compound according to claim 10, wherein R4, R5, R6 and R7, independently of each other, are hydrogen, CrC2alkyl, CrC2haloalkyl or Ci-C2alkoxyCi-C2alkyl.
12. A compound according to claim 1 , wherein Y is O.
13. A compound according to claim 1 , wherein R1 is ethyl, methyl or cyclopropyl, R2 is phenyl or phenyl substituted by halogen or Ci-C2alkyl, R3 is hydrogen, R4, R5, R6 and R7, independently of each other, are Ci-C2alkyl, and Y is O. ion of a compound of formula I
Figure imgf000054_0001
wherein R1 to R7 and n are as defined in claim 1 , which comprises reacting a compound of formula (F)
Figure imgf000054_0002
la (D)
Figure imgf000054_0003
tion of a compound of formula I
Figure imgf000055_0001
wherein R1 to R7 and n are as defined in claim 1 , which comprises reacting a compound of formula (C)
la (D)
ula (B)
Figure imgf000055_0002
and further reaction with an oxidizing agent.
16. A process for the preparation of a compound of formula (A)
Figure imgf000055_0003
which comprises reacting a compound of formula (I)
Figure imgf000056_0001
with an acid.
PCT/EP2010/057121 2009-05-29 2010-05-25 Spiro epoxides as intermediates WO2010136431A1 (en)

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BRPI1014691-1A BRPI1014691A2 (en) 2009-05-29 2010-05-25 Compound, and process for the preparation of a compound.
US13/375,223 US8680299B2 (en) 2009-05-29 2010-05-25 Spiro epoxides as intermediates
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JP2012512334A JP5735491B2 (en) 2009-05-29 2010-05-25 Spiroepoxide as an intermediate
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