Synthesis of Polyhydroxylated Quinolizidine and Indolizidine Scaffolds from Sugar-Derived Lactams via a One-Pot Reduction/Mannich/Michael Sequence

A direct approach to the synthesis
of indolizidine and quinolizidine
scaffolds of iminosugars is described. The presented strategy is based
on a one-pot sugar lactam reduction with Schwartz’s reagent
followed by a diastereoselective Mannich/Michael tandem reaction of
the resulting sugar imine with Danishefsky’s diene. The stereochemical
course of the investigated reaction has been explained in detail.
The obtained bicyclic products are attractive building blocks for
the synthesis of various naturally occurring polyhydroxylated alkaloids
and their derivatives.

本文报道了一种构建亚氨基糖（iminosugars）吲哚里西啶（indolizidine）与喹啉里西啶（quinolizidine）骨架的直接合成方法。所提出的合成策略采用一锅法流程：先利用施瓦茨试剂（Schwartz’s reagent）还原糖内酰胺，随后使生成的糖亚胺与丹尼谢夫斯基二烯（Danishefsky’s diene）发生非对映选择性曼尼希/迈克尔串联反应。本文详细阐释了所研究反应的立体化学进程。所得双环产物是合成多种天然存在的多羟基生物碱及其衍生物的优质合成砌块。