Use of Menthyl 2-Methoxynaphthalene-1-sulfinates in the Andersen Synthesis of Optically Active Sulfoxides. Facile Cleavage by Grignard Reagents of Some Aromatic Methyl Ethers

Abstract

The pure crystalline diastereomers (1R,2S,5R)-menthyl (R)- and (S)-2-methoxynaphthalene-1-sulfinate (1b) have been prepared and, by reaction with Grignard reagents (the Andersen procedure), converted into optically active alkyl and aryl 2-methoxynaphthyl sulfoxides in 67-77% yields. Use of an excess of Grignard reagent results in facile O-alkyl cleavage of the methoxy group to the corresponding naphthol or a competing loss of the alkyl- or aryl- sulfinyl group to form 2-methoxynaphthalene. Pure diastereomers of menthyl 2,7- dimethoxynaphthalene-1-sulfinate (2b) and menthyl 4-methoxynaphthalene-1-sulfinate (3b) have also been prepared and their reactions with Grignard reagents have been studied.