2-Methoxyphenyl acetones

The fourth part of this review concerns the development of the previously described intramolecular cyclisation of 2-methoxyphenyl acetones and 2-hydroxy-3-(2-methoxyphenyl)propenoic acids leading to 2-substituted benzofurans [17, 38]. 

Dimethoxybenzoic acid Tetramethylene dichloride p-Methoxyphenyl acetone Ethylamine... 

The methoxy derivatives may be treated directly o-methoxyphenyl-acetone, heated with hydrobroniic acid in acetic acid, gives 2-methyl-benzofuran.326 o-Methoxylated phenylacetones are readily prepared by glycidic synthesis from o-methoxylated aromatic aldehydes the intermediate glycidic ester (127) can be directly converted by pyridine hydrochloride into a 2-alkylbenzofuran in 40-80% yield.105... 

The present procedure is that described by the submitter.3 It is an improved modification of that described by Hoover and Hass4 for the corresponding para isomer. o-Methoxyphenyl-acetone has also been prepared from the glycidic ester.5... 

Difunctional target molecules are generally easily disconnected in a re/ro-Michael type transform. As an example we have chosen a simple symmetrical molecule, namely 4-(4-methoxyphenyl)-2,6-heptanedione. Only p-anisaldehyde and two acetone equivalents are needed as starting materials. The antithesis scheme given helow is self-explanatory. The aldol condensation product must be synthesized first and then be reacted under controlled conditions with a second enolate (e.g. a silyl enolate plus TiCl4 or a lithium enolate), enamine (M. Pfau, 1979), or best with acetoacetic ester anion as acetone equivalents. 

In a 2-1. three-necked round-bottomed flask, fitted with an efficient sealed stirrer and a reflux condenser capped by a drying tube, are placed the dried anisyl chloride (Notes 2 and 3), 73.6 g. (1.5 moles) of finely powdered sodium cyanide, 10 g. of sodium iodide, and 500 ml. of dry acetone (Note 4). The heterogeneous reaction mixture is heated under reflux with -sngorous stirring for 16-20 hours, then cooled and filtered with suction. The solid on the filter is washed with 200 ml. of acetone and discarded (Note 5). The combined filtrates are distilled to remove the acetone. The residual oil is taken up in 300 ml. of benzene and washed with three 100-ml. portions of hot water. The benzene solution is dried over anhydrous sodium sulfate for about 15 minutes, and the solvent is removed by distillation at the reduced pressure of the water aspirator (Note 6). The residual -methoxyphenyl-acetonitrile is purified by distillation under reduced pressure through an 8-in. Vigreux column b.p. 94—97°/0.3 mm. 1.5285-1.5291. The yield is 109-119 g., or 74-81% based on anisyl alcohol (Notes 7 and 8). 

A variant on this structure, dioxyline, has much the same activity as the natural product but shows a better therapeutic ratio. Reduction of the oxime (113) from 3,4-dimethoxyphenyl-acetone (112) affords the veratrylamine homolog bearing a methyl group on the amine carbon atom (114). Acylation of this with 4-ethoxy-3-methoxyphenyl acetyl chloride gives the corresponding amide (115). Cyclization by means of phosphorus oxychloride followed by dehydrogenation over palladium yields dioxyline (116). ... 

D) 4 -[N-Ethyi-1 "-Methyl-2 -(4" -Methoxyphenyl)Ethylamino]Butyi-3,4-Dimethoxybenzoate Hydrochloride 10.3 g of 4 -iodobutyl-3,4-dimethoxybenzoate and 11.0 g of N-ethyl-p-methoxyphenylisopropylamine (obtained by catalytic reduction of an alcoholic solution of an excess quantity (60%) of p-methoxy-phenyl-acetone, to which was added a 33% (weight-for-weight) aqueous solution of ethylamine, with Pt as a catalyst), were boiled in 200 ml of methyl ethyl ketone for 20 hours, cooled and the iodine ion was determined the reaction was found to be complete. Then the methyl ethyl ketone was evaporated in vacuo and the residue was dissolved in 300 ml of water and 30 ml of ether the layers were separated and the water layer was extracted twice more with 20 ml portions of ether. 

The material was purified by recrystallization from ethanol with the addition of activated carbon. In this manner 24.2 g 1,3-dimethyl-4-[7-[4-(o-methoxyphenyl]-piperizinyl-(1)] pro-pylamino] -uracil having a melting point of 10O C were obtained corresponding to a yield of 75%. The purification may also be effected by boiling the material in acetone to result in similar yields. 

In a sensitive and specific colorimetric method 1,1,1-trichloro-2,2-bis(p-methoxyphenyl)-ethane is extracted from plant or animal tissue, using benzene or petroleum ether as the solvent. The solvent is evaporated at room temperature by a current of air and the residue dehydroha log ena ted with 2% alcoholic potassium hydroxide. By petroleum ether extraction the resulting 1,1-dichloro-2,2-bis(p-methoxyphenyl)-ethylene is removed from the reaction mixture. After the solvent is removed by air evaporation the dehydroha log ena ted methoxychlor is isolated from the nonsaponifiable portion of the fats and waxes by dissolving the residue in hot acetone, chilling, and filtering. After the acetone is removed by air evaporation, the residue is treated with 85% sulfuric acid. This produces a red solution with an absorption maximum at 555 m/z, the intensity of which can be read on a colorimeter and is a function of the methoxychlor concentration. Beer s law is obeyed over the range of 1 to 50 micrograms. 

Reduction of diaryltellurium dichlorides with sodium ascorbate (typical procedure). Bis (p-methoxyphenyl)tellurium dichloride (0.20 g, 0.48 mmol) dissolved in acetone (10 mL) was added to a stirred solution of sodium ascorbate (0.20 g, 1.0 mmol) in water/methanol (2+8 mL). After 24 h, water (50 mL) and CH2CI2 (50 mL) were added and the two phases separated. The organic phase was dried (CaCl2) and the solvent evaporated in vacuo. Flash chromatography yielded 0.14 g (84%) of bis(p-methoxyphenyl) telluride. 

Preparation of various enantiomerically pure sulfoxides by oxidation of sulfides seems feasible in the cases where asymmetric synthesis occurs with ee s in the range of 90% giving crystalline products which can usually be recrystallized up to 100% ee. Aryl methyl sulfides usually give excellent enantioselectivity during oxidation and are good candidates for the present procedure. For example, we have shown on a 10-mmol scale that optically pure (S)-(-)-methyl phenyl sulfoxide [a]p -146 (acetone, o 1) could be obtained in 76% yield after oxidation with cumene hydroperoxide followed by flash chromatographic purification on silica gel and recrystallizations at low temperature in a mixed solvent (ether-pentane). Similarly (S)-(-)-methyl o-methoxyphenyl sulfoxide, [a]p -339 (acetone, o 1.5 100% ee measured by HPLC), was obtained in 80% yield by recrystallizations from hexane. 

A well-stirred solution of 6.8 g of the mixed isomers of 1 -(2,3,6-tri-methoxyphenyl)propene in 40 g of dry acetone was treated with 3.2 g pyridine and cooled to 0 °C with an external ice bath. There was then added 6.5 g tetranitro-methane over the course of 1 min, the stirring was continued for an additional 2 min, and then the reaction mixture was quenched by the addition of 2.2 g KOH in 40 mL H20. There was additional H,0 added, and the organics were extracted with 3x75 mL CH,C12. The solvent from the pooled extracts was removed under vacuum, and the 5.3 g residue distilled at 0.2 mm/Hg. A fraction boiling at 150-170 °C proved to be largely 2,3,6-trimethoxybenzaldehyde. A second fraction (170-200 °C at 0.2 mm/Hg) also spontaneously crystallized to a yellow solid. This was recrystallized from MeOH to provide, after drying to constant weight, 2.8 g of 2-nitro-1 -(2,3,6-trimethoxyphenyl)propene with a mp of 73-74 °C. Anal. (C 2H N05) C,H. 

The resulting reaction solution was poured into 200 ml of ice water, and the toluene phase was separated off and washed twice with water. The required amount of hydrochloric acid was added to the toluene solution, the toluene was distilled off under reduced pressure and the residue, which remained was recrystallized from acetone to give l,7-bis-(2-methoxyphenyl)-3-methylaza-7-cyanononadecane hydrochloride or a-dodecyl-3-methoxy-a-[3-[[2-(3-methoxyphenyl)ethyl] methyl amino] propyl] benzene-acetonitrile (anipamil) ... 

---