Angelmicin B is a potently cytotoxic glycoside natural product isolated from the actinomycete Microbispora species. While the relative stereochemistry of this glycoside have been reported, the stereochemistry of the three sugars relative to the aglycone remains unassigned. The objectives of this proposal are three-fold: The first involves the synthesis of the hindered glycosyl acceptor segment of angelmicin B by way of a neighboring-group assisted oxocarbenium annulation cascade. Second, the enantioselective synthesis of the three deoxyglycosides found in angelmicin B will be performed. When both the glycosyl acceptor and the enantiopure monosaccharides are in hand, methodology for alpha- and beta- stereoselective glycosylations of hindered substrates will be established. Finally, stereochemical correlations between the model system and the natural product will be performed in order to determine the stereochemistry of the sugars relative to the aglycone. ? ? ?
