Modulation of the coordination geometries of NCN and NCNC Rh complexes for ambidextrous chiral catalysts
作者:Jun-ichi Ito、Takahiro Ishihara、Takaki Fukuoka、Siti Rokiah Binti Mat Napi、Hajime Kameo、Hisao Nishiyama
DOI:10.1039/c9cc06520b
日期:——
A chirality switch between novel NCN pincer Rh complexes and a related double cyclometalated NCNC Rh complex containing secondary amino groups is described. Their catalytic abilities were determined in asymmetric alkynylation of ethyltrifluoropyruvate, and the change in the coordination geometry of the Rh catalysts affected the stereochemistry of the products.
A novel ruthenium catalyst is introduced which contains solely achiral ligands and acquires its chirality entirely from octahedral centrochirality. The configurationally stable catalyst is demonstrated to catalyze the alkynylation of trifluoromethyl ketones with very high enantioselectivity (up to >99% ee) at low catalyst loadings (down to 0.2 mol%).