Benzyl-2-carbomethoxycyclopentanone

The stirrer is started, and the solution in the addition funnel is added over a 2-hour period without external heating (Note 3). After the addition is complete, the mixture is heated under reflux for 2.5 hours, at the end of which time the mixture has a pasty consistency. A solution of 106 g. (0.84 mole) of benzyl chloride in 100 ml. of dry benzene is added in one portion, the mixture heated under reflux for 14 hours, and the solution (Note 4) poured into 600 ml. of water. The benzene layer is separated, the aqueous layer extracted twice with ether, and the combined benzene-ether extract washed with 100 ml. of water and dried over anhydrous sodium sulfate. The. solvent is removed under reduced pressure using a rotary evaporator, and the residual liquid distilled to yield 108-116 g. (81-86%) of colorless 2-benzyl-2-carbomethoxycyclopentanone, b.p. 126-128° (0.5 mm.) (Note 5). 

This preparation of 2-benzyl-2-carbomethoxycyclopentanone is based on a procedure described by Baker and Leeds for the ethyl ester, and the methyl ester has not been previously prepared. The ethyl ester, also, has been prepared by the alkylation of 2-carbethoxycyclopentanone with benzyl chloride in the presence of potassium hydroxide in acetaldehyde dipropylacetal. The preparation and isolation of the potassium salt of 2-carbethoxycyclopentanone can be readily achieved in a very simple way... 

A. 2-Benzyl-2-carbomethoxycyclopentanone. A dry 2-1. threenecked flask is fitted with a Vibromischer stirrer (Note 1), a reflux condenser, and a 250-ml. dropping funnel with a pressureequalizing side tube. A nitrogen-inlet tube is connected to the top of the dropping funnel, and an outlet tube is placed on the... 

The preparation of 2-benzylcyclopentanone from 2-benzyl-2-carbomethoxycyclopentanone has not been previously reported. Starting with the ethyl ester, however, the compound has been prepared by heating the ester for many hours with concentrated hydrochloric acid. - The direct alkylation of cyclopentanone with benzyl chloride in the presence of sodium amide in liquid ammonia goes only in a poor yield. ... 

A soln. of 2-benzyl-2-carbomethoxycyclopentanone in 2,4,6-collidine added to a refluxing soln. of lithium iodide dihydrate in the same solvent, and refluxed 19 hrs. under Ng 2-benzylcyclopentanone. Y 72-76%, Also preferential de-carbomethoxylation s. F. Elsinger, Org. Synth. 45, 7 (1965). 

Benzy 1 2 carbomethoxycyclopentanone from 2 carbomethoxycyclopentanone and benzyl chloride, 45, 8 2 Benzylcyclopentanone, 46, 7 N Benzyloxycarbonylglycine, 46, 49 Benzyltnmethylammonium hydroxide as catalyst for condensation of benzil with dibenzyl ketone, 46,... 

Carbethoxycyclohexanone, 46, 82 2-Carbethoxycyclononanone, 47, 22 2-Carbethoxycyclooctanone, 47, 20 2-Carbomethoxycyclopentanone, conversion to 2-benzyl-2-carbometh-oxycyclopentanone, 45, 8 Carbon disulfide, reaction with /i-chloro-aniline and aqueous ammonia,... 

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