Shahrestani N, Khosravi H, Jadidi K, Notash B, Naderi S. Organocatalytic synthesis of enantiopure spiro acenaphthyl-pyrrolizidine/pyrrolidines: justifying the regioselectivity based on a distortion/interaction model.
Org Biomol Chem 2019;
17:7013-7024. [PMID:
31305857 DOI:
10.1039/c9ob01197h]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
An efficient organocatalytic [3 + 2] reaction with Schreiner's thiourea organocatalyst for the synthesis of a small library of novel enantiopure stable spiroacenaphthyl-pyrrolidines/pyrrolizidines with high regio- and diastereoselectivity (up to 99%) is described for the first time. These chiral compounds were synthesized by a three-component 1,3-dipolar cycloaddition of (E)-1-(2-oxoacenaphthylen-1(2H)-ylidene) pyrrolidin-1-ium-2-ide as a dipolar and (S)-cinnamoyl/crotonoyl oxazolidinone as a dipolarophile. The absolute configuration of cycloadducts was confirmed by X-ray diffraction analysis. The origin of catalyst reactivity and regio- and stereoselectivity was investigated through DFT calculations. DFT calculations showed that the regioselectivity was controlled by the distortion (deformation) of reactants and Schreiner's thiourea acts as a LUMO-lowering catalyst.
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