Shimizu M, Hirano K, Satoh T, Miura M. Waste-free synthesis of condensed heterocyclic compounds by rhodium-catalyzed oxidative coupling of substituted arene or heteroarene carboxylic acids with alkynes.
J Org Chem 2009;
74:3478-83. [PMID:
19388716 DOI:
10.1021/jo900396z]
[Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The direct oxidative coupling of 2-amino- and 2-hydroxybenzoic acids with internal alkynes proceeds efficiently in the presence of a rhodium/copper catalyst system under air to afford the corresponding 8-substituted isocoumarin derivatives, some of which exhibit solid-state fluorescence. Depending on conditions, 4-ethenylcarbazoles can be synthesized selectively from 2-(arylamino)benzoic acids. The oxidative coupling reactions of heteroarene carboxylic acids as well as aromatic diacids with an alkyne are also described.
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