Synthesis and Facile Dearomatization of Highly Electrophilic Nitroisoxazolo[4,3-
b]pyridines.
MOLECULES (BASEL, SWITZERLAND) 2020;
25:molecules25092194. [PMID:
32397095 PMCID:
PMC7248838 DOI:
10.3390/molecules25092194]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 11/16/2022]
Abstract
A number of novel 6-R-isoxazolo[4,3-b]pyridines were synthesized and their reactions with neutral C-nucleophiles (1,3-dicarbonyl compounds, π-excessive (het)arenes, dienes) were studied. The reaction rate was found to be dependent on the nature of the substituent 6-R. The most reactive 6-nitroisoxazolo[4,3-b]pyridines are able to add C-nucleophiles in the absence of a base under mild conditions. In addition, these compounds readily undergo [4+2]-cycloaddition reactions on aromatic bonds C=C(NO2) of the pyridine ring, thus indicating the superelectrophilic nature of 6-NO2-isoxazolo[4,3-b]pyridines.
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