Tymann DC, Benedix L, Iovkova L, Pallach R, Henke S, Tymann D, Hiersemann M. Photochemical Approach to the Cyclohepta[b]indole Scaffold by Annulative Two-Carbon Ring-Expansion.
Chemistry 2020;
26:11974-11978. [PMID:
32463529 PMCID:
PMC7540574 DOI:
10.1002/chem.202002581]
[Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Indexed: 12/12/2022]
Abstract
We report on the implementation of the concept of a photochemically elicited two-carbon homologation of a π-donor-π-acceptor substituted chromophore by triple-bond insertion. Implementing a phenyl connector between the slide-in module and the chromophore enabled the synthesis of cylohepta[b]indole-type building blocks by a metal-free annulative one-pot two-carbon ring expansion of the five-membered chromophore. Post-irradiative structural elaboration provided founding members of the indolo[2,3-d]tropone family of compounds. Control experiments in combination with computational chemistry on this multibond reorganization process founded the basis for a mechanistic hypothesis.
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