Catalyst-Free Stereocontrolled Formal [3 + 2]-Cycloaddition of CO<sub>2</sub> for the Synthesis of Enantiopure Spiro[indoline-3,5′-oxazolidine]-2,2′-diones under Aqueous and Ambient Conditions
Saumen Hajra, Anurag Biswas
Abstract
A highly efficient regio- and stereoselective spontaneous formal [3 + 2]-cycloaddition of CO2 in aqueous medium is developed for the one-pot synthesis of spiro[indoline-3,5′-oxazolidine]-2,2′-diones with excellent enantiopuirity (ee up to 99%) under catalyst-free and ambient conditions. The detailed study reveals NH-spiroaziridine- and 3-(aminomethyl)-3-chloro-oxindoles, two in situ generated reactive intermediate compounds for the spontaneous cycloaddition with CO2, and the latter is responsible for the stereoselectivity. An unprecedented mechanism of desulfinylation is also disclosed herewith.
Topics & Concepts
OxazolidineCycloadditionChemistryEnantiopure drugStereoselectivityIndolineCatalysisAqueous solutionCombinatorial chemistryOrganic chemistryStereochemistryEnantioselective synthesisCarbon dioxide utilization in catalysisSynthesis and Catalytic ReactionsAsymmetric Hydrogenation and Catalysis