Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/77—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D307/93—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom ortho- or peri-condensed with carbocyclic rings or ring systems condensed with a ring other than six-membered

Definitions

• the present invention relates to a process for preparing 1 ,2,6,7-tetrahydro-8H- indeno[5,4-b]furan-8-one.
• EP-A-0 885 210, EP-A- 1 792 899 and Uchikawa et al. describe methods for the preparation of 1 ,2,6,7-tetrahydro-8/- -indeno[5,4-?]furan- 8-one as an intermediate in the preparation of indenofurannitrile starting from 2,3-dihydrobenzofuran. This route involves numerous and complex reaction steps and the overall yield is low.
• the object of the present invention was to provide a simple and cost efficient process for preparing 1 ,2,6,7-tetrahydro-8H-indeno[5,4-fo]furan-8-one having a reduced number of steps and resulting in good yields.
• step (ii) reducing the ozonide formed in step (i) in the presence of methanol to form 2- methoxy-I ⁇ J-tetrahydro-SH-indeno ⁇ -bJfuran-S-one of the formula (III)
• Ozonolysis of compound (II) in step (i) of the process of the invention is typically carried out in an organic solvent inert under the reaction conditions.
• suitable organic solvents include alcohols, ethers and halogenated hydrocarbons.
• Preferred alcohols are methanol, ethanol and isopropanol.
• Preferred ethers are isopropyl ether, diethyl ether and tetrahydrofuran (THF).
• Preferred halogenated hydrocarbons are dichloromethane, chloroform and 1 ,2-dichloroethane. Solvents may be used alone or as mixtures of 2 or more.
• a mixture of methanol and dichloromethane is preferred, wherein the methanol/dichlormethane ratio (v/v) is typically of from 1 :100 to 100:1 , for example 1 :10.
• reaction of compound (II) with ozone (O3) is carried out by bubbling ozone through a solution of the starting compound (II).
• the required ozone may be generated, for example, by an ozone generator using oxygen or compressed air as gas source.
• Ozonolysis is conventionally carried out at temperatures below 0 °C, typically at temperatures in a range of from -100 °C to 0 °C.
• the reaction is usually carried out at -78 °C in a cooling bath of dry ice/acetone.
• Reaction time is typically in a range of from 0.5 hrs to 48 hrs, preferably of from 5 hrs to 15 hrs.
• excess ozone is advantageously removed from the reaction mixture, preferably by purging the reaction mixture with an inert gas, such as nitrogen.
• the ozonide formed as an intermediate in ozonolysis is reduced in the presence of a reducing agent to allow ring closure so as to form the compound of the formula (III), advantageously in the presence of a reducing agent that does not reduce aldehydes.
• the reducing agent is added to the reaction mixture typically after completion of ozonolysis and removal of excess ozone.
• suitable reducing agents to be added include triphenylphosphine (PPh 3 ) and dimethyl sulfide ((CH 3 ) 2 S).
• the reducing agent is preferably used in at least equimolar amounts relative to the starting material, in particular in a molar ratio of from 1 :1 to 2:1. It is believed that the reducing agent reduces the ozonide to the aldehyde which together with methanol forms the cyclic acetal of formula (III).
• Reduction temperature is not critical and reduction is typically carried out at a temperature in the range of from 0 °C to 45 °C, for example at ambient temperature.
• Reaction time is typically in a range of from 0.5 hrs to 48 hrs, preferably of from 5 to 15 hrs.
• the 2-methoxy-1 > 2,6,7-tetrahydro-8/-/-indeno[5,4-/)]furan-8-one of the formula (III) obtained in step (i) is a novel compound and thus is also subject of the present invention. This compound may be used in step (iii) of the present process with or without purification.
• Elimination of methanol in step (iii) of the process of the invention to form compound (IV) is typically performed in an organic solvent.
• suitable organic solvents include aromatic hydrocarbons, ethers and alkyl cyanides.
• aromatic hydrocarbons are toluene and benzene.
• Preferred ethers are diisopropyl ether, diethyl ether and tetrahydrofuran.
• Preferred alkyl cyanide is acetonitrile.
• the solvents may be used alone or as mixtures of 2 or more.
• Preferred solvent is toluene.
• Elimination in step (iii) is typically carried out in the presence of inorganic and organic acids or bases as a catalyst.
• Acids and bases are typically used in catalytic amounts, for example in a molar ratio of from 0.001 :1 to 1 :1 with respect to the compound of the formula (III).
• inorganic bases include alkali and earth alkali carbonates and hydrogen carbonates, such as potassium carbonate and potassium hydrogen carbonate, alkali hydrides, such as sodium hydride and potassium hydride, and alkali and earth alkali hydroxides, such as sodium hydroxide and potassium hydroxide.
• Preferred organic bases include alkali alkoholates such as sodium methanolate, sodium ethanolate, sodium tert-butylate and potassium tert-butylate, and tertiary amines such as triethylamine, triethylenediamine, tri(n-butyl)amine, diisopropylethylamine, N,N-dimethyl- aniline and pyridine.
• suitable acids are protic acids and Lewis acids.
• Preferred protic acids are toluenesulfonic acid (TsOH), methanesulfonic acid and sulfuric acid with TsOH being preferred.
• Preferred Lewis acid is boron trifluoride (BF 3 ) which is usually provided in the form of a BF 3 adduct.
• Typical adducts include ether adducts such as BF 3 (CH 3 ) 2 0, BF 3 (C 2 H 5 ) 2 0, BF 3 (C 4 H 9 ) 2 O and BF 3 THF with BF 3 (CH 3 ) 2 0 being preferred.
• Elimination is typically carried out at a temperature of from 20 °C to 150 °C, preferably of from 80 °C to 130 °C, for example at 110 °C.
• Reaction time is typically in a range of from 10 min to 24 hrs, preferably of from 0.5 hrs to 5 hrs.
• Hydrogenation of 6,7-dihydro-8H-indeno-[5,4-£>]furan-8-one of the formula (IV) in step (iv) of the process of the invention is typically performed in an organic solvent.
• suitable organic solvents include organic acids, organic esters, alcohols, ethers and tertiary amines.
• organic acids include formic acid, acetic acid and propionic acid.
• An example of an organic ester is ethyl acetate.
• examples of alcohols include methanol, ethanol and isopropanol.
• examples of ethers include diisopropyl ether, diethyl ether and tetrahydrofuran.
• An example of a tertiary amine is triethylamine.
• the solvents may be used alone or as mixtures of 2 or more.
• a mixture of ethanol and tetrahydrofuran is preferred.
• the ethanol/tetrahydrofuran ratio (v/v) is typically in a range of from 1 :20 to 20:1 , for example 2:1.
• a tertiary amine is added to the reaction mixture to reduce the catalytic activity of the hydrogenation catalyst, typically in an amount of from 1 :100 to 1 :1000 (v/v) relative to the total volume of the reaction mixture.
• Hydrogenation typically is a catalytic hydrogenation using hydrogen in the presence of a hydrogenation catalyst.
• hydrogenation catalysts typically the elements of group 10 of the periodic table, i.e., Ni, Pd and Pt, are used. Further useful hydrogenation catalysts include Rh, Ru, Fe and Co. Examples of catalysts include Pd(OH) 2 -C, Pd on carbon, Raney-Ni and Lindlar Pd.
• the amount of added catalyst in the present invention is typically of from 2.5 % to 50 % (w/w) relative to the starting material.
• the catalyst is added in an amount of from 10 % to 40 % (w/w), such as 25 % (w/w), relative to the starting material.
• Preferred catalyst is Pd on carbon, such as 5 % Pd/C (w/w).
• the hydrogen pressure in the hydrogenation reaction is typically of from 0.05 MPa to 5.0 MPa, preferably of from 0.2 to 3.0 MPa, more preferably of from 0.5 to 0.7 MPa.
• hydrogenation is carried out at a reaction temperature of from 0 °C to 60 °C, preferably of from 15 °C to 45 °C, more preferred of from 30 °C to 35 °C.
• Reaction time is typically in a range of from 5 hrs to 80 hrs, preferably of from 20 hrs to 60 hrs, more preferably of from 30 hrs to 50 hrs.
• step (iv) of the process of the invention may be further subjected to a condensation reaction to form indenofurannitrile following general procedures described in the literature (see, e.g., Uchikawa, O. et al., J. Med. Chem, 2002, 45, 4222-4239).
• 6-hydroxy-7-allyl-indan- 1-one of the formula (II) may be obtained by a two step process starting from commercially available 6-hydroxy-1-indanone of the formula (V) according to known methods (see, e.g., Rodrigues, D.C. et al., Magn. Reson. Chem. 2000, 38, 970-974, and Gering H.L. et al., J. Am. Chem. Soc. 1958, 3277-3285).
• 6-hydroxy-1-indanone of the formula (V) may be subjected to allylation using an allyl halogenide, such as allyl chloride or allyl bromide in acetone to give 6-allyloxy-indan-1-one of the formula (VI).
• 6-Allyloxy-indan- 1-one of the formula (VI) may be further subjected to a thermal rearrangement reaction (Claisen rearrangement) to give 6-hydroxy-7-allyl-indan-1-one of the formula (II).
• Ion source APCI in Positive Module
• Ion source El in Positive Module
• Ion source temp 250 °C
• Electron energy 70 eV; Scan mode: full scan;
• 6-Hydroxy-7-allyl-indan-1-one of the formula (II) (16 g, 99 %, 84.2 mmol) was dissolved in methanol/dichloromethane (32 ml/320 ml) at ambient temperature. The solution was cooled to -78 °C in a dry ice-acetone bath. A stream of O3 was bubbled through the stirred solution. The ozone was produced by an ozone generator using compressed air as gas source (flow rate, 2 l/min). The progress of the reaction was monitored by thin layer chromatography (TLC) until absence of starting material. After the reaction was completed (ca. 10 hrs), excess ozone was removed by purging the reaction mixture with nitrogen for 1 hr.
• TLC thin layer chromatography
• 6-Hydroxy-1-indanone of the formula (V) (74.1 g, 0.50 mol), K 2 C0 3 (166.0 g, 1.2 mol), acetone (750 ml) and allyl bromide (52 ml, 0.6 mol) were charged into a 1000 ml flask.
• 6-Allyloxy-indan-1-one of the formula (VI) (112 g, 0.6 mol) and A/,A/-dimethylaniline (110 ml) were charged into a 500 ml flask. The mixture was heated to reflux under N2 and stirred for 12-13 hrs. The reaction was monitored by HPLC. After the reaction was finished, the solution was cooled quickly to 25 °C in a water-bath. Aqueous HCI (6 N, 250 ml) and ice-water (200 ml) were added subsequently. The mixture was stirred for further 5 minutes and then extracted with ethyl acetate (500 ml ⁇ 2, and 300 ml). The combined organic phases were washed with saturated brine (400 ml).

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• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2010
  • 2010-09-29 CN CN201080042317.1A patent/CN102648192B/zh not_active Expired - Fee Related
  • 2010-09-29 WO PCT/EP2010/005941 patent/WO2011044990A1/en active Application Filing
  • 2010-09-29 EP EP10763319A patent/EP2483258A1/en not_active Withdrawn

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