鎖状系における高ジアステレオ選択的アミノ化法とアミノ糖合成

Abstract

We have found prominent 1, 2- and 1, 3-asymmetric induction in the intramolecular conjugate additions of γ- and δ-carbamoyloxy- α, β-unsaturated esters. They provide a good way to achieve diastereoselective amination of acyclic olefinic systems, since complementary diastereoface-selection is accomplished by changing the site of carbamoyloxy group between γ- and δ-positions, as summarized in Fig. 15; almost complete stereocontrol is achieved by using Z-olefins. We demonstrated the synthetic utility of this method by the stereoselective syntheses of all four possible diastereomers of racemic N- acyl 3-amino-2, 3, 6-trideoxyhexose. Furthermore, N-acyl derivatives, 5, 7 and 8, of three naturally occurring sugars were synthesized in a stereodivergent manner starting from L-lactate. The antiperiplanar effect was revealed to play a major role in the reactions of homoallyic carbamates with allylic chiral center.