Trofimov BA, Volkov PA, Telezhkin AA, Khrapova KO, Ivanova NI, Albanov AI, Gusarova NK. Catalyst-Free Double CH-Functionalization of Quinolines with Phosphine Oxides via Two S
NHAr Reaction Sequences.
J Org Chem 2020;
85:4927-4936. [PMID:
32162918 DOI:
10.1021/acs.joc.0c00084]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quinolines undergo catalyst-free double CH-functionalization upon treatment with secondary phosphine oxides (70-75 °C, 20-48 h) followed by oxidation of the intermediate 2,4-bisphosphoryltetrahydroquinolines with chloranil. The yields of the target 2,4-bisphosphorylated quinolines are up to 77%. Thus, a double-SNHAr reaction sequence in the same molecule of quinoline has been realized. In the case of 2,4-bisphenylphosphoryltetrahydroquinolines, the aromatization occurs with elimination of one molecule of diphenylphosphine oxide to afford the products of monofunctionalization, 4-diphenylphosphorylquinolines, in 40-45% yields.
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