Question 20.36: Outline the steps required to convert methylenecyclohexane t......
Outline the steps required to convert methylenecyclohexane to each of the following compounds.
(a) cyclohexanecarboxylic acid (b) cyclohexylacetic acid (c) 1-methylcyclohexanecarboxylic acid
(a) Prepare cyclohexylmethanol using B₂H₆ followed by treatment with basic hydrogen peroxide (the hydroboration–oxidation procedure). Then oxidize the alcohol to the carboxylic acid using the Jones reagent.
(b) Add HBr in the presence of peroxide to give a primary halogen compound (anti-Markovnikov addition). Prepare the Grignard reagent using magnesium and ether and then add it to carbon dioxide, followed by acidification in workup. Alternatively, displace bromide ion by cyanide ion, followed by hydrolysis of the nitrile.
(c) Add HBr to give a tertiary halogen compound. Prepare the Grignard reagent using magnesium and ether and then add it to carbon dioxide, followed by acidification in workup.