o-Toluic acid has been converted into methyl (8RS, 9SR)-7-(bromomethyl)-8, 9-dimethyl-1, 4- dioxaspiro [4.5] dec-6-ene-8-carboxylate, the stereochemical defining step being a conjugate addition of lithium dimethylcuprate to a cyclohexadienone prepared using a Birch reduction followed by an allylic oxidation. Displacement of the bromide with various propargylic alcohols followed by reduction of the ester and protection of the primary ...
