Rhodium-Catalyzed Asymmetric Construction of Quaternary Carbon Stereocenters: Ligand-Dependent Regiocontrol in the 1,4-Addition to Substituted Maleimides
摘要:
A rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to substituted maleimides has been described. The regioselectivity in this reaction is controlled by the choice of ligand (dienes or bisphosphines), and 1,4-adducts with a quaternary stereocenter can be obtained with high regio- and enantioselectivity by the use of (R)-H8-binap.
A full overview on the use of chiralphosphine-olefinligands 1 in the rhodium-catalyzedasymmetric1,4-addition of arylboronic acids to alpha,beta-unsaturated carbonyl compounds is described. Effective chiral environment of a Rh/1 complex was shown to resemble that of a Rh/(R,R)-Ph-bod* complex by comparing the experimental results as well as the X-ray crystal structures. High catalytic activity of
描述了手性膦-烯烃配体 1 在铑催化的芳基硼酸不对称 1,4-加成到 α,β-不饱和羰基化合物中的使用的完整概述。通过比较实验结果和 X 射线晶体结构,表明 Rh/1 复合物的有效手性环境类似于 Rh/(R,R)-Ph-bod* 复合物的手性环境。公开了 Rh/1 复合物的高催化活性,并通过使用反应量热计和 (31) P NMR 光谱的机理研究建立了涉及三聚体-单体平衡的催化循环。还成功地观察到源自催化剂的非活性三聚体活性单体平衡的负非线性效应。