Nelson R, Gulías M, Mascareñas JL, López F. Concise, Enantioselective, and Versatile Synthesis of (-)-Englerin A Based on a Platinum-Catalyzed [4C+3C] Cycloaddition of Allenedienes.
Angew Chem Int Ed Engl 2016;
55:14359-14363. [PMID:
27735111 DOI:
10.1002/anie.201607348]
[Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Indexed: 01/01/2023]
Abstract
A practical synthesis of (-)-englerin A was accomplished in 17 steps and 11 % global yield from commercially available achiral precursors. The key step consists of a platinum-catalyzed [4C+3C] allenediene cycloaddition that directly delivers the trans-fused guaiane skeleton with complete diastereoselectivity. The high enantioselectivity (99 % ee) stems from an asymmetric ruthenium-catalyzed transfer hydrogenation of a readily assembled diene-ynone. The synthesis also features a highly stereoselective oxygenation, and a late-stage cuprate alkylation that enables the preparation of previously inaccessible structural analogues.
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