A New Synthesis of Pyrrolidines by Way of an Enantioselective Mannich/Diastereoselective Hydroamination Reaction Sequence
摘要:
A new two-step synthesis of highly substituted pyrrolidines has been developed. Chiral silane Lewis acid promoted enantioselective Mannich reactions of silyl ketene imines with acylhydrazones may be used to access bishomoallylic benzoic hydrazides that In turn may be cyclized to pyrrolidines by way of the thermal hydroamination reaction reported recently by Beauchemin. Importantly, excellent diastereoselectivity may be realized in the hydroamination reactions.
Highly Enantioselective Mannich Reactions with α-Aryl Silyl Ketene Acetals and Imines
作者:Gregory T. Notte、Jenny M. Baxter Vu、James L. Leighton
DOI:10.1021/ol103096u
日期:2011.2.18
Mannich reactions with chiral silicon Lewis acid activated acylhydrazones and α-aryl silylketeneacetals and α-aryl,α-alkyl silylketeneimines proceed efficiently and with good to excellent levels of both diastereoselectivity and enantioselectivity. The reactions provide access to α-aryl,β-hydrazido esters and α-aryl,α-alkyl,β-hydrazido nitriles, which are valuable analogs of β-amino acids.