Formaldehyde SAMP-Hydrazone as a Neutral Formyl Anion Equivalent: Asymmetric Synthesis of Substituted β-Formyl δ-Lactones and Furofuran Lactones
作者:Dieter Enders、Juan Vázquez、Gerhard Raabe
DOI:10.1002/(sici)1099-0690(200003)2000:6<893::aid-ejoc893>3.0.co;2-u
日期:2000.3
β-formyl δ-lactones 5 (de ≥ 98%, ee = 80-95%) and 4-substituted furofuran lactones 6 (de ≥ 98%, ee = 80->98%) in acceptable overall yields is reported. Key steps of the new procedure are an asymmetric Michael addition of formaldehyde SAMP-hydrazone (1) to 5,6-dihydro-2H-pyran-2-one (2) under neutral conditions, followed by trans-selective α-alkylation and subsequent cleavage of the auxiliary by ozonolysis
α-β取代的甲酰基δ内酯的有效不对称合成5(DE≥98%,EE = 80-95%)和4-取代的内酯Furofuran型6(德≥98%,EE = 80-> 98%)在报告了可接受的总产量。该新方法的关键步骤是在中性条件下将甲醛SAMP hydr(1)不对称地添加到5,6-二氢-2 H-吡喃-2-酮(2)中,然后进行反式-选择性α-烷基化和随后通过臭氧分解或水解多米诺反应方案裂解助剂。给出的标题化合物的绝对构型基于三种X射线结构分析和NOE测量。