Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C249/00—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton
  • C07C249/16—Preparation of compounds containing nitrogen atoms doubly-bound to a carbon skeleton of hydrazones

Definitions

• the present invention relates to a process for the preparation of aryl hydrazones and their use in making aryl hydrazines.
• Aryl hydrazines are used widely as intermediates in agrochemical and pharmaceutical synthetic processes, particularly in the synthesis of compounds having heterocyclic rings.
• Ar represents an optionally substituted aromatic carbocycle or heterocycle
• R 1 and R 2 independently represent hydrogen, C ⁇ o alkyl, C ⁇ C O alkyl or optionally substituted aryl provided that R 1 and R 2 are not both hydrogen which process comprises reacting together a compound of formula (H):
• R 1 and R 2 are as defined in relation to formula (I) under aqueous conditions in the presence of a Pd (II) salt, a ligand and a Group I or Group II metal hydroxide base at a pH greater than 7.
• alkyl refers to fully saturated straight or branched hydrocarbon chains having from one to ten, preferably one to six carbon atoms. Examples include methyl, ethyl, itpropyl, iso-propyl, ivbutyl, t ⁇ butyl and n-hexyl. Expressions such as “alkoxy” and “haloalkyl” should be construed accordingly.
• halogen includes fluorine, chlorine, bromine and iodine.
• Haloalkyl groups are alkyl groups which are substituted with one or more of the same or different halogen atoms and are, for example, CF 3 , CF 2 C1, CH 2 CF 3 , CH 2 CH 2 CF 3 , CH 2 (CF 2 ) 2 CH 3 , CH 2 CHF 2 or CH 2 CF 2 CF 2 CF 3 .
• the reaction is preferably performed in the absence of air.
• organic solvent is hydrocarbons such as aromatic carbocycles for example methyl substituted benzenes, ethers such as tetrahydrofuran or alcohols such as methanol, ethanol and octanol.
• Preferred organic solvents are aromatic carbocyclic hydrocarbons such as methyl substituted benzenes.
• a particularly useful organic solvent is toluene or xylene.
• the compounds of formula (I) may be hydrolysed to aryl hydrazine compounds of formula (IN)
• the process of the invention enables preparation of aryl hydrazones and aryl hydrazines using simple, inexpensive inorganic bases, under aqueous conditions, and is a relatively inexpensive process compared with that described in the prior art process which uses an expensive base (potassium t-butoxide) and which necessitates anhydrous conditions.
• Typical aromatic carbocycle groups Ar and aryl groups R and R are ring systems that may be mono-, bi- or tricyclic. Examples of such rings include phenyl, naphthalenyl, anthracenyl or phenanthrenyl, preferably phenyl.
• Typical aromatic heterocycle groups Ar are aromatic ring systems containing at least one heteroatom and consisting either of a single ring or of two or more fused rings.
• single rings will contain up to three and bicyclic systems up to four heteroatoms which will preferably be chosen from nitrogen, oxygen and sulphur.
• Examples of such groups include furyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, 1,2,5-thiadiazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, 1,2,3-triazinyl,
• heteroaromatic radicals include pyridyl, pyrimidyl, triazinyl, thienyl, furyl, oxazolyl, isoxazolyl, and thiazolyl.
• a preferred ring for Ar is phenyl.
• the substituents are one or more groups independently selected from alkyl, halogen, cyano, nitro, haloalkyl, amino, acylamino, HO 2 C, C ⁇ - 6 alkoxy (itself optionally substituted by C 1-6 alkoxy), aryl(C 1-4 )alkoxy, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, C 1-6 alkylaminocarbonyl, di(C ⁇ _ 6 alkyl)aminocarbonyl, phenyl, halophenyl, C ⁇ -6 alkylphenyl, Ci- ⁇ alkoxycarbonyl-phenyl, C 1-6 alkoxyphenyl, heteroaryl, aryloxy, arylcarbonyloxy, heteroaryloxy, heterocyclyl, heterocyclyloxy, C 3- cycloalkyl, C 3- cycloalkyloxy, C 5-7 cycloalkenyl
• substituents for R 1 , R 2 and Ar include C 1-8 alkyl, halogen, cyano, nitro, C ⁇ -8 haloalkyl, acylamino, and C 1-6 alkoxy (itself optionally substituted by C 1-6 alkoxy). More preferred substituents for R 1 , R 2 and Ar include . 6 alkyl, halogen, nitro, trifluoromethyl and C 1-6 alkoxy.
• R 1 and R 2 are independently C 1-8 alkyl, phenyl or phenyl substituted by one or more of C ⁇ -8 alkyl, halogen, cyano, nitro, C 1-8 haloalkyl, acylamino, and C 1-6 alkoxy (itself optionally substituted by C 1-6 alkoxy).
• R 1 and R 2 are independently C ⁇ -6 alkyl, phenyl or phenyl substituted by one or more of C ⁇ -6 alkyl, halogen, nitro, trifluoromethyl or C ⁇ -6 alkoxy.
• Ar is phenyl or phenyl substituted by one or more of C 1-8 alkyl, halogen, cyano, nitro, C ⁇ -8 haloalkyl, acylamino, and C ⁇ -6 alkoxy (itself optionally substituted by C ⁇ _ 6 alkoxy).
• Ar is phenyl or phenyl substituted by one or more of C 1-6 alkyl, halogen, nitro, trifluoromethyl or C ⁇ alkoxy.
• a preferred leaving group X is I, Br, Cl, -O-triflate or O-tosylate.
• Suitable compounds that may be prepared by the invention include 3-trifluoromethyl- phenyl hydrazine, 4-methoxy-phenyl hydrazine, 4-nitro-phenyl hydrazine and 4- chloro- phenyl hydrazine.
• the base is sodium, potassium or lithium hydroxide or a hydroxide or oxide of magnesium, calcium or caesium.
• the Pd (II) salt catalyst is preferably palladium chloride or palladium acetate.
• the ligand is 2,2XBis(diphenylphosphino)-l,l'-binaphthyl (BINAP) either as a racemate or as (S)-(-)-2,2XBis(diphenylphosphino)-l, -binaphthyl).
• BINAP 2,2XBis(diphenylphosphino)-l,l'-binaphthyl
• the function of the ligand is to generate the catalytic species.
• the reaction is preferably performed at a temperature of from 50°C to 150°C.
• the temperature is from 70°C to 130°C, even more preferably 80°C to 100°C.
• the reaction may be operated at atmospheric pressure or at elevated pressure.
• the ratio of compounds of formula (II to formula (IH) is preferably from 3:1 to 1:3, more preferably 1.5:1 to 1:1.5, more preferably 1:1.
• the pH is greater than 9, more preferably greater than 10.
• EXAMPLE 1 This example illustrates the preparation of N-(3-benzotriflouro)-benzophenone hydrazone
• the palladium acetate, BINAP and toluene (previously degassed with helium) were charged to the reactor in a nitrogen atmosphere and the mixture was stirred for 10 minutes.
• the 3-bromobenzotrifluoride and benzophenone hydrazone were charged to the reactor.
• the aqueous sodium hydroxide solution (previously degassed with helium) was added and the mixture was heated to 90°C and stirred at that temperature for 7.25 hours.
• the reaction mixture was cooled to room temperature and allowed to stand overnight. The reaction was continued the next day by heating to 90°C. After a further 7 hours, the mixture was cooled, 15ml water was added to dissolve precipitated solid and the two phases were separated.
• the toluene phase was washed with water (15ml) and the solvent was removed at 40°C and reduced pressure on a rotary evaporator.
• the yield of product was 93%.

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 2001
  • 2001-10-23 GB GBGB0125442.4A patent/GB0125442D0/en not_active Ceased
• 2002
  • 2002-10-02 EP EP02762609A patent/EP1440053A1/en not_active Withdrawn
  • 2002-10-02 JP JP2003538120A patent/JP2005506380A/ja not_active Withdrawn
  • 2002-10-02 CA CA002463261A patent/CA2463261A1/en not_active Abandoned
  • 2002-10-02 US US10/493,503 patent/US7138548B2/en not_active Expired - Fee Related
  • 2002-10-02 WO PCT/GB2002/004459 patent/WO2003035604A1/en not_active Ceased

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