DEVELOPMENT OF A NOVEL PATHWAY TO ACCESS 6-DEOXY-6,6,6-TRIFLUOROSUGARS VIA 1,2-MIGRATION OF A TERT-BUTYLDIMETHYLSILYL GROUP

Trifluoromethylated furanols 2 were enzymatically resolved into the corresponding optically active forms in a highly efficient manner and were further converted to the synthetically useful 2-butenolides 6. Introduction of substituents into these butenolides 6 or their saturated lactone forms 8 was realized by boron trifluoride-mediated Michael addition of cuprates or by capture of the enolates with various kinds of electrophiles, respectively, both of which proceeded with a high degree of diastereoselectivity. Moreover, novel synthetic routes to access 6-deoxy-6,6,6-trifluorosugars were developed by the utilization of 1,2-silyl migration as a key step, which was qualitatively supported by PM3 molecular orbital calculation.