Enantioselective arylation of aldehydes catalyzed by a soluble optically active polybinaphthols ligand
作者:Xiaobo Huang、Linglin Wu、Jinqian Xu、Lili Zong、Hongwen Hu、Yixiang Cheng
DOI:10.1016/j.tetlet.2008.09.072
日期:2008.11
soluble chiral polymer ligand was synthesized by the polymerization of (R)-6,6′-dibutyl-3,3′-diformyl-2,2′-binaphthol (R-M-1) with 2,5-diaminopyridine (M-2) via a nucleophilic addition–elimination reaction. While arylboronic acids were used as the source of the transferable aryl group, the chiral polybinaphthols ligand in combination with Et2Zn without Ti(OiPr)4 exhibited higher enantioselectivity in asymmetric
通过(R)-6,6'-二丁基-3,3'-二甲酰基-2,2'-联萘酚(R -M-1)与2,5-二氨基吡啶(M -2)通过亲核加成-消除反应。尽管芳基硼酸用作可转移芳基的来源,但手性聚二萘酚配体与Et 2 Zn结合而没有Ti(O i Pr)4与芳族醛相比,在芳族醛的不对称加成中表现出更高的对映选择性。当与吸电子基团的芳族醛被选择作为底物,在比那些具有给电子基团作为底物更高的ee值值产生的所得diarylmethanols。用作底物的2-萘甲醛可提供95%ee的产物,这可归因于空间效应对该不对称芳基化反应的影响。此外,手性聚合物易于回收和再利用,但在第三次循环中表现出对映选择性降低。