Regio- and Stereoselective Addition of Allylmetal Reagents to Pyridinium−π and Quinolinium−π Complexes
作者:Shinji Yamada、Mai Inoue
DOI:10.1021/ol070168q
日期:2007.4.1
Regio- and stereoselective allylation of pyridinium and quinolinium salts was performed by the addition of allylindium and allyltributyltin reagents toward intermediary cation-pi complexes. The reaction with allylindium and allyltributyltin reagents afforded a 1,2-adduct, whereas the addition of a prenylindium reagent gave a 1,4-adduct with good regio- and stereoselectivities. X-ray structural analysis, H-1 NMR studies, and DFT calculations elucidated the intermediary cation-pi complex formation with face-to-face orientation.
Face-Selective Addition to a Cation−π Complex of a Pyridinium Salt: Synthesis of Chiral 1,4-Dihydropyridines
作者:Shinji Yamada、Chisako Morita
DOI:10.1021/ja0203317
日期:2002.7.1
Selective shielding of one side of the pyridinium face by way of intramolecular cation-pi complex formation enabled nucleophiles to attack only from the non-shielded side, and consequently, chiral 1,4-dihydropyridines were produced stereoselectively with up to 99% de. The structure of the cation-pi complex was elucidated by 1H NMR studies and X-ray analysis.
通过分子内阳离子-π 复合物形成选择性屏蔽吡啶鎓面的一侧,使亲核试剂仅从非屏蔽侧进行攻击,因此,手性 1,4-二氢吡啶以高达 99% 的 de 立体选择性产生。通过 1 H NMR 研究和 X 射线分析阐明了阳离子-pi 复合物的结构。