Transition from Kwon [4+2]- to [3+2]-cycloaddition enabled by AgF-assisted phosphine catalysis

• Published in: Nature communications Vol. 15; no. 1; pp. 6995 - 9
• Main Authors: Qian, Jinlong, Zhou, Lijin, Wang, Yuyi, Zhou, Xiaoyu, Tong, Xiaofeng
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 14.08.2024; Nature Publishing Group UK; Nature Portfolio
• Subjects: Catalysis; Catalysts; Cycloaddition; Phosphine; Phosphines; Silver; Stereoselectivity; Substrates; Zwitterions
• ISSN: 2041-1723
• DOI: 10.1038/s41467-024-51295-9

Phosphine catalysis generally relies on the potential of carbanion-phosphonium zwitterions that are generated via nucleophilic addition of phosphine catalyst to electrophilic reactants. Consequently, structural modification of zwitterions using distinct electrophilic reactants has emerged as a prominent strategy to enhance catalysis diversity. Herein, we present an alternative strategy that utilizes AgF additive to expand phosphine catalysis. We find that AgF can readily transform the canonical carbanion-phosphonium zwitterion into silver enolate-fluorophosphorane intermediate, eventually furnishing a P(III)/P(V) catalytic cycle. This strategy has been successfully applied to the phosphine-catalyzed reaction of 2-substituted allenoate and imine, resulting in the transition from Kwon [4 + 2] cycloaddition to [3 + 2] cycloaddition. This [3 + 2] cycloaddition features remarkable diastereoselectivity, high yield, and broad substrate scope. Experimental and computational studies have validated the proposed mechanism. Given the prevalence of carbanion-phosphonium zwitterions in phosphine catalysis, this AgF-assisted strategy is believed to hold significant potential for advancing P(III)/P(V) catalysis.