Base-free enantioselective S_N2 alkylation of 2-oxindoles via bifunctional phase-transfer catalysis.

ABSTRACT: N-Protected oxindole derivatives of unprecedented malleability bearing ester moieties at C-3 have been shown to participate in enantioselective phase-transfer-catalysed alkylations promoted by ad-hoc designed quaternary ammonium salts derived from quinine bearing hydrogen-bond donating substituents. For the first time in such phase-transfer-catalysed enolate alkylations, the reactions were carried out under base-free conditions. It was found that urea-based catalysts outperformed squaramide derivatives, and that the installation of a chlorine atom adjacent to the catalyst's quinoline moiety aided in avoiding selectivity-reducing complications related to the production of HBr in these processes. The influence of steric and electronic factors from both the perspective of the nucleophi

SUBMITTER: Litvajova M 

PROVIDER: S-EPMC8450950 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature