Chemical resolution of secondary (±)-alcohols

The preparative resolution of optically active alcohols might proceed most readily by direct esterification with optically active acids except that few esters crystallize satisfactori1y.l We have now found that many secondary (&)-alcohols can be resolved by esterification with L-amino acids using p-toluenesulphonic acid (p-TsOH) and that sterically pure, crystalline p-toluenesulphonates of the L-amino acid (+)-alkyl esters can be obtained in good yields (6040% of the available ( +)-isomer).