Organotransition metal modified sugars 4. Carbene complex functionalized acyclic carbohydrates

A synthetic strategy based on a combination of sugar electrophiles and transition metal nucleophiles allows the metal carbene functionalization of acyclic carbohydrates. Following this methodology the per-O-acetylated methoxycarbene complexes 8-14 are prepared in moderate to good yields. Upon reaction with ammonia they undergo aminolysis to give the aminocarbene complexes 16-18. H-1-NMR studies indicate that in solution the D-galacto and L-arabino complexes adopt extended planar zigzag conformations. A similar conformational preference is observed for the solid state as established by X-ray studies on the D-galacto derivatives 8 and 15. (C) 1997 Elsevier Science S.A.