STUDIES DIRECTED TO THE SYNTHESIS OF THE ANTIFUNGAL ANTIBIOTIC ALEURODISCAL - ENANTIOSELECTIVE CONSTRUCTION OF AN ADVANCED BETA-D-XYLOSIDE CONGENER

The first synthesis of a highly functionalized congener of aleurodisca l is reported. An enantiocontrolled route to tricyclic ketone 8 was fi rst developed by taking advantage of regiodirected tandem methylation and vinylation of a phenylsulfanyl precursor, as 23 --> 24 --> 8. Thes e experiments formed the basis for the coupling of 8 to 30, in turn pr epared from (4S)-(-)-tert-butyldimethylsiloxycyclopentenone, prior to oxy-anionic Cope rearrangement. Phenylselenenylation of the enolate io n generated in this manner ultimately led to a pair of dienone isomers , whose distinctively different chemistries were made apparent at seve ral levels. Notable features of the overall approach include the intro duction of stereogenic centers positioned remotely from each other acr oss a medium-sized ring and stereoselective bond construction via a bo atlike transition state following efficient conjoining of the two key segments.