Petzold M, Günther A, Jones PG, Werz DB. Regio- and Diastereoselective Dimerization of Diazo Carbonyls: A Cooperative Catalytic Approach to Complex Scaffolds with Four Contiguous Stereocenters.
Chemistry 2020;
26:11119-11123. [PMID:
32237096 PMCID:
PMC7497023 DOI:
10.1002/chem.202001548]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Indexed: 12/20/2022]
Abstract
Starting from readily available o-diazoacyl-substituted arene carboxylates, scaffolds with the 5,9-epoxycyclohepta[b]pyran-2(3H)-one core were obtained by cooperative RhII , Lewis and Brønsted acid catalysis. Four new bonds, three functional groups (lactone, ketal, and alcohol) and four contiguous stereocenters are formed during this regio- and diastereoselective process in a single synthetic step. Intensive optimization and mechanistic studies, including the trapping, isolation, and elucidation of reaction intermediates, led to a plausible mechanistic scenario. The reaction is proposed to involve carbonyl ylides but also transient species of the ketocarbene equilibrium that undergo a cascade of cycloaddition and skeletal rearrangements.
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