Synthesis of 2-Fluoro Analogues of Frontalin

摘要

The synthesis of enantiomerically and diastereomerically pure (-)-(1R,2R,5R)- and (-)-(1R,2S,5R)-2-fluoro frontalin (7) starting from (+)-(1S)-menthyl-(R)-toluene-4-sulfinate, methylmagnesium bromide, methyl fluoroacetate, 4-pentenyl bromide and diazomethane is described. The absolute stereochemistry was unambiguously determined by X-ray analysis of (+)-(1S,2R,5S,R_S)-5, an intermediate in the synthesis of the enantiomeric (+)-(1S,2R,5S)-2-fluoro frontalin (7).