Stereocontrolled Access to Quaternary Centers by Birch Reduction/Alkylation of Chiral Esters of Salicylic Acids.

8-Phenylmenthol esters of salicylic acid derivatives undergo efficient Birch reduction and diastereoselective alkylations to afford methoxycyclohexadienes bearing new quaternary stereogenic centers. The use of an ester-based auxiliary is a designed improvement over the use of prolinol-derived amides, which are expensive and often very difficult to cleave.