ASYMMETRIC-SYNTHESIS OF ALKANESULFINATES AND ARENESULFINATES OF DIACETONE-D-LUCOSE (DAG) - AN IMPROVED AND GENERAL-ROUTE TO BOTH ENANTIOMERICALLY PURE SULFOXIDES

Diacetone-D-glucose (DAG), a commercially available, sugar-derived secondary alcohol, was found to react with alkane- and arenesulfinyl chlorides in the presence of a tertiary amine in a very useful manner. When i-Pr2Net is used as the base, (-)-(S)-alkane- and arenesulfinates are obtained in 50-90% yield with 89-greater-than-or-equal-to 95% de. Simply changing the base from i-Pr2NEt to Py affords (+)-(R)-alkane- and arenesulfinates in 56-87% yield with 70-greater-than-or-equal-to 95% de. The de's were determined by H-1 NMR. Optically pure alkane- and arenesulfinates are obtained either by recrystallization or by column chromatography. These sulfinates were transformed into various enantiomerically pure sulfoxides (alkyl alkyl and alkyl aryl) by reaction with different Grignard reagents. This new methodology is cheap, quick, and very convenient when both enantiomers of a given sulfoxide are needed enantiomerically pure. The influence of the solvent, as well as the effect of other types of bases, on the stereochemical course of the reaction has been evaluated, and a possible origin of the diastereoselectivity is discussed. Other optically pure secondary alcohols are used m the same reaction, and the comparison of their behavior with that of DAG is also reported.