Stereoselective Preparation of Ceramide and Its Skeleton Backbone Modified Analogues via Cyclic Thionocarbonate Intermediates Derived by Catalytic Asymmetric Dihydroxylation of α,β-Unsaturated Ester Precursors
作者:Linli He、Hoe-Sup Byun、Robert Bittman
DOI:10.1021/jo001226n
日期:2000.11.1
yields. Furthermore, propargylic alpha-azido-beta-hydroxyester 10a is converted to D-erythro-sphingosine 2a via simultaneous reduction of the triple bond, azido, and ester functional groups with LiAlH(4), providing a highly concise and practical four-step synthesis of this key naturally occurring sphingolipid. The L-erythro stereoisomers are also available in high enantiomeric purity by the method described
报道了一种新颖且有效的合成途径,制备神经酰胺1a和骨架骨架修饰的神经酰胺类似物1b,c。合成利用(催化的(E)-α,β-不饱和酯5a-c的a催化不对称二羟基化作为手性诱导步骤,产物1a-c,2a和13中的所需构型是通过在区域上进行区域选择性叠氮化物取代而产生的α,β-二羟基酯6a-c通过环状硫代碳酸酯中间体的α位。通过叠氮化物还原,N-酰化,酯还原(NaBH(4)/ LiBr)和三键桦木还原(Li,EtNH(2))的序列将叠氮基酯10a-c转换为相应的神经酰胺1a-c。 )。这些七到八步的合成过程提供了具有出色立体控制效果的目标化合物1a-c,且总收率达30-42%。此外,通过与LiAlH(4)同时还原三键,叠氮基和酯官能团,将炔丙基α-叠氮基-β-羟基酯10a转化为D-赤型-鞘氨醇2a,从而提供了高度简洁和实用的四步合成方法关键天然存在的鞘脂。L-赤型立体异构体也可通过本文所述的方法以高对映体纯度获得。