Reductive methylenation of ketones to give allyl alcohols

Abstract

The yield of the allyl alcohols was 10-30%. A sample of 21.3 g dibutyl ketone was added dropwise to a i i0 (mass ratio) mixture of KOH amd DMSO at 100-110=C over 2 ho Treatment with water, extraction with ether, and distillation gave3.3 g (14%) 2-propyl-l-hepten-3-ol, bp 670C (2 mm), n 2~ 1.4468, d~ ~ 0.8281. Analogous procedures gave 3-ethyl-l-hexen-3-ol (lla) in 10% yield, ~p 51=C (2 mm), ~t D 1.4422, d4 a~ 0.8521, and 2-methylenecyaloheptanol (llc) in 30% yield, bp 57=C (1.5 mm), nD 2~ 1.4900, d~ 2~ 0.9662. The elemental analysis data correspond to the chemical formulas of these compounds. The PM2R spectra of (IIa-c) display signals for protons at the double bond at 4.8-5.0 ppm, the methine proton at 3.8-4.3 ppm and alkyl group protons at 0.2-0.8 ppm. The ~C NMR spectrum has signals for the carbon nuclei of the double bond, COH group and alkyl groups. The IR spectra of the alcohols synthesized have bands corresponding to the double bond at 1665 and 3090 cm -: and the hydroxyl group at 1080 and 3290-3420 cm -*.