strategy to construct chiral secondary C–O bonds for quaternary carbon stereocenters at the nonadjacent β-position is described. Methylene 1,3-oxazolidine-2,4-diones were for the first time employed in an asymmetric reaction as viable electrophiles undergoing a tandem conjugate addition–protonation process. Using an L-amino acid-based urea–tertiary amine catalyst, the reaction with 3-substituted oxindoles
Highly enantioselective phase-transfer alkylation of 3-substituted-2-oxindoles with activated bromomethanes is disclosed with a broad substrate scope by using bicyclic guanidinium as a catalyst and a Lewis acid as the co-catalyst. The alkylation adducts are versatile intermediates to accomplish the syntheses of pyrroloindolines and furoindolines.
PyBroP-mediated nucleophilic addition of oxindoles with pyridine N-oxides to access 3-pyridyl-3,3-disubstituted oxindoles
作者:Fuzhong Han、Wenjia Xiao、Lina Jia、Xiangping Hu
DOI:10.1039/d3nj04907h
日期:——
A sustainable and efficient strategy for the synthesis of 3-pyridyl-3,3-disubstituted oxindole derivatives has been achieved via PyBroP (bromotripyrrolidinophosphonium hexafluorophosphate) promoted nucleophilic addition reaction of oxindoles with pyridine N-oxides. The approach worked well under relatively mild conditions. The protocol features a broad substrate scope and good functional group tolerance