Enantioselective Copper-Catalyzed Conjugate Addition of Trimethylaluminium to β,γ-Unsaturated α-Ketoesters
作者:Ludovic Gremaud、Alexandre Alexakis
DOI:10.1002/anie.201107324
日期:2012.1.16
Not a cop out: The copper‐catalyzed asymmetric conjugateaddition of organometallic reagents to Michael acceptors is an important methodology for forming a CC bond in an enantioselective manner. Such an addition of Me3Al to β,γ‐unsaturatedα‐ketoesters is described to proceed in high yield and selectivity. CuTC=copper(I) thiophene‐2‐carboxylate.
We report herein the enantioselectiveCu-catalyzed conjugate addition of organometallic reagents to sensitive Michael acceptors and their application to the synthesis of relevant target molecules. This is one of the most important methodologies to form a C-C bond in an enantioselective manner. A wide range of alpha,beta-unsaturated aldehydes and beta,gamma-unsaturated-alpha-ketoesters has been successfully
Bifuctional Amino-Squaramides Catalyzed Asymmetric Spiroannulation Cascades with Aliphatic β,γ-Unsaturated α-Keto Esters: Controlling an Aldehyde Enolate
作者:Xiaoqin Wang、Weijun Yao、Zhihui Yao、Cheng Ma
DOI:10.1021/jo202633c
日期:2012.3.16
A quinidine-derived squaramide Ib catalyzed cyclization reaction of beta-oxo aldehydes 1 and aliphatic or aromatic beta,gamma-unsaturated alpha-keto ester 2 is described. Using cyclic aldehyde substrates, this procedure provided a promising approach to a variety of spiro-3,4-dihydropyrans bearing three continuous quaternary and tertiary stereocenters in moderate to good yield with high stereoselectivities. Substituents on the nitrogen atoms of the squaramide moiety of the catalyst proved crucial to the reaction outcome. The stereochemistry of the three newly formed chiral centers (trans-selective) of the major product indicates a Micheal addition/hemiacetalization domino sequence for the present annulations.