Munakala A, Nallamilli T, Nanubolu JB, Chegondi R. Steric- and Electronic-Controlled Intramolecular [2 + 2]-Cycloaddition of Cyclohexadienone-Containing 1,7-Enynes.
Org Lett 2022;
24:892-896. [PMID:
35023756 DOI:
10.1021/acs.orglett.1c04232]
[Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Herein we have developed the silver-catalyzed electronic- and steric-controlled intramolecular formal [2 + 2]-cycloaddition of alkyne-tethered cyclohexadienones. Substrates with electron-rich alkynes and a less hindered quaternary carbon center afford tricyclic fused cyclobutenes through 1,7-enyne cyclization. In contrast, the formation of dihydrofurans was observed from electron-deficient alkynes via proton abstraction/C-O bond cleavage. The synthetic potential of this method was also broadened with a gram-scale reaction and various transformations on cyclobutene.
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