  In our quest to achieve chemoselective amidoglycosylation of D-galactal 3-carbamates as a means for 2-aminotalose synthesis, we have explored factors that affect the fate of primary-carbamate-derived acyl nitrene 1 . This reactive intermediate can lead to either desired amino sugar 2  or to C3-oxidized dihydropyranone 3 . With rhodium nitrenoids, we have found that 4O-tert-butyldimethylsilyl-6O-tosyl protection is optimal, and we observed a corresponding conformational shift in the carbamate precursor as judged by 4JH2,H4 W-coupling (or lack thereof). Furthermore, switching to copper catalysis provided even higher chemoselectivity.

Rhodium- and copper-catalyzed formation of 2-talosamine derivatives from D-galactal 3-carbamates

243rd National Meeting (2012)

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