7-Mesityl-2,2-dimethylindan-1-ol: a novel alcohol which serves as both a chiral auxiliary and a protective group for carboxy functions

Abstract

A novel chiral indanol 11 is conveniently synthesized by using a stepwise displacement of the methoxy groups of 2,6-dimethoxybenzoic ester 1 by a vinyl and then an aryl Grignard reagent as the key step. The racemic indanol 11 is optically resolved as the diastereomeric (S_a)-2′-methoxy-1,1′-binaphthyl-2-carboxylic esters 12 by column chromatography. The absolute stereochemistry of the indanol (+)-11 is established to be S by an X-ray crystallographic analysis of the ester (S_a,S)-12. Performance of the indanol 11 as a chiral auxiliary, and as a protective group for the carboxy function, is examined in the atrolactic acid synthesis from phenylglyoxylic ester 13 and methylmagnesium iodide and in the biphenyl coupling reaction of 2,3-dimethoxybenzoic ester 15 with 2-methoxy-4,6-dimethylphenylmagnesium bromide, resulting in quantitative formations of atrolactic ester 14 with up to 83% de and biphenyl 16 with 72% de, respectively.