artificial catalysts for asymmetric synthesis. Polyfunctional catalysts are considered to be a promising tool for achieving excellent catalytic efficiency. A polyfunctional catalyst system was developed, which incorporates two Lewisacidic/Brønsted basic cobalt centers in combination with triazolium moieties that are crucial for high reactivity and excellent stereoselectivity in the direct1,4‐addition of
stereoselective addition of oxindoles to α,β‐unsaturated aldehydes, generating valuable chiral scaffolds with contiguous quaternary and tertiary stereocenters (see scheme). For the first time, a chiral primary amine thiourea catalyst has been successfully applied for iminium‐ion activation.
The bifunctional quinine-derived thiourea catalyst 14 was found to catalyze the direct amination of unprotected3-aryl and aliphatic substitutedoxindoles with di-tert-butylazodicarboxylate (DBAD) to construct a tetrasubstituted stereogenic carbon center at the C-3 position of oxindoles in good to excellent yield and enantioselectivity.
A practical strategy has been developed for the bioinspired and ligand-regulated chemoselective unnatural prenylation and geranylation of oxindoles with isoprene under Pd catalysis. The selectivity was governed by modulating the coordination geometry of the Pd catalyst.
A Bench‐stable 8‐Aminoquinoline Derived Phosphine‐free Manganese (I)‐Catalyst for Environmentally Benign C(α)‐Alkylation of Oxindoles with Secondary and Primary Alcohols
作者:Parul Saini、Pritam Dolui、Abhishek Nair、Ashutosh Verma、Anil J. Elias
DOI:10.1002/asia.202201148
日期:2023.3.14
air-stable, phosphine-free 8-aminoqunoline (8-AQ) based Mn(I) carbonyl complex as the catalyst for the C(α)-alkylation of oxindoles with alcohols has been developed. The Mn complex [(8-AQ)Mn(CO)3Br] works effectively as a catalyst for α-alkylation of oxindoles by both secondary as well as primary alcohols. Few pharmaceutically relevant compounds were also synthesized by this method in good yields.