Thirupathi G, Ashok E, Suresh Kumar A, Ramachary DB. Parts-per-Million-Level, Catalytic [3+2]-Annulations for the Asymmetric Synthesis of Methanobenzo[7]annulenes.
Chemistry 2021;
27:18033-18038. [PMID:
34677886 DOI:
10.1002/chem.202103254]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Indexed: 12/11/2022]
Abstract
3-Alkyl-lawsones selectively reacted with α-alkyl-nitroethylenes under 500 parts-per-million (ppm) quinine-NH-thiourea-catalysis to furnish the chiral methanobenzo[7]annulenes in up to >99 % ee with >20 : 1 dr and TON up to 1820 through tandem Michael/Henry [3+2]-annulations. These asymmetric ppm-level, catalytic tandem [3+2]-annulations would be highly inspirational for the design of many more ppm-level organocatalytic reactions, and at the same time these final molecules are basic skeletons of antibiotics.
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