Title

1,2-Addition versus homoconjugate addition reactions of indoles and electron-rich arenes to α-cyclopropyl N -acyliminium ions: Synthetic and computational studies

RIS ID

137721

Publication Details

Ryder, G. M., Wille, U., Willis, A. C. & Pyne, S. G. (2019). 1,2-Addition versus homoconjugate addition reactions of indoles and electron-rich arenes to α-cyclopropyl N -acyliminium ions: Synthetic and computational studies. Organic and Biomolecular Chemistry, 17 (29), 7025-7035.

Abstract

An investigation of the reactivity of α-cyclopropyl N-acyliminium ions towards indoles has resulted in the unprecedented synthesis of 5-cyclopropyl-5-(3-indoyl)pyrrolidin-2-ones via 1,2-addition reactions and, in the case of highly electron deficient indoles and electron rich arenes, spiroheterocycles via sequential homoconjugate and 1,2-addition reactions with often high diastereoselective control at the C-5 quaternary stereocentres. Computational studies provided support for the proposed mechanisms and stereochemical outcome of these reactions, clearly showing that the 1,2-addition pathway is kinetically controlled. In reactions where the 1,2-adduct is destabilised, for example when the arene ring is less nucleophilic, the 1,2-addition is reversible and the thermodynamically preferred homoconjugate addition and subsequent rearrangement and cyclisation reactions become the major pathway.

Grant Number

ARC/DP130101968

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