Synthesis of Mixed Acyloins. VI

Behaviors of Grignard Reagents towards Alicyclic Ketone Cyanohydrins

Abstract

The reaction of methylmagnesium iodide with cyclopentanone and cyclohexanone cyanohydrins respectively give 1-methylcyclopentanol, b.p₁₀₀ 80-85° (phenylurethan, m. p. 91°), in 70% yield and 1-methylcyclohexanol, b.p₂₁ 60-64° (phenylurethan, m. p. 105°), in 71.6% yield, but there is no formation of the corresponding 1-acetyl-cycloalkanol. On the contrary, reaction of the cyanohydrins and phenylmagnesium bromide affords 1-benzoylcyclopentanol, b.p₇ 140-145° (semicarbazone, m. p. 195°), in 53.6% yield and 1-benzoylcyclohexanol, b.p₇ 150-154° (oxime, m. p. 121-121.5°), in 32.7% yield. In general, the reaction of the Grignard reagents with aliphatic ketonecyanohydrins progresses towards the formation of tert-carbinols but in the reaction of acetone cyanohydrin with phenylmagnesium bromide, 2-benzoyl-2-propanol, b.p₇ 110-113° (semicarbazone, m. p. 185°), was obtained in a good yield of 56.7%, similar to the case of alicyclic compounds.