Phosphine-Catalyzed [4+1] Cycloadditions of Allenes with Methyl Ketimines, Enamines, and A Primary Amine

Ze-Hun Cao, Yu-Hao Wang, Subarna Jyoti Kalita, Uwe Schneider, Yi-Yong Huang

Research output: Contribution to journalArticlepeer-review

Abstract

Unprecedented phosphine-catalyzed [4+1] cycloadditions of allenyl imides have been discovered using various N-based substrates including methyl ketimines, enamines, and a primary amine. These transformations provide a one-pot access to cyclopentenoyl enamines and imines, or (chiral) γ-lactams via two geminal C-C bond or two C-N bond formations, respectively. Several P-based key intermediates including a 1,4-(bis)electrophilic α,β-unsaturated ketenyl phosphonium species have been detected by 31P NMR and HRMS analyses, which shed light on the postulated catalytic cycle. The synthetic utility of this new chemistry has been demonstrated through a gram-scaling up of the catalytic reaction as well as regioselective hydrogenation and double condensation to form cyclopentanoyl enamines and fused pyrazole building blocks, respectively.

Original languageEnglish
Pages (from-to)1884-1890
Number of pages7
JournalAngewandte Chemie International Edition
Volume59
Issue number5
Early online date20 Nov 2019
DOIs
Publication statusPublished - 27 Jan 2020

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