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1,2-Addition to trifluoromethylated β-enamino diketones: regioselective synthesis of trifluoromethyl-containing azomethine pyrazoles and isoxazoles

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Abstract

A simple and efficient methodology for highly regioselective synthesis of azomethine pyrazoles and isoxazoles containing a trifluoromethyl group is reported. The cyclocondensation of trifluoromethylated β-enamino diketones (TBED) with phenylhydrazine and hydroxylamine hydrochloride, in the presence of BF3, provided 5-aryl-4-[(tert-butyl)iminomethyl]-3-trifluoromethylazoles by aza-Michael-type 1,2-addition. The scope of the reaction was expanded by transimination with arylamines in a one-pot method starting from TBED. Thus, 83 novel 4-[(alkyl/aryl)iminomethyl]-3-trifluoromethylazoles were obtained with high regioselectivity and in yields of 51 to 89%.

Graphical abstract: 1,2-Addition to trifluoromethylated β-enamino diketones: regioselective synthesis of trifluoromethyl-containing azomethine pyrazoles and isoxazoles

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Article information


Submitted
13 Feb 2020
Accepted
11 Mar 2020
First published
11 Mar 2020

Org. Biomol. Chem., 2020, Advance Article
Article type
Paper

1,2-Addition to trifluoromethylated β-enamino diketones: regioselective synthesis of trifluoromethyl-containing azomethine pyrazoles and isoxazoles

K. E. Pianoski, J. Poletto, M. J. Vieira da Silva, J. N. Ascencio Camargo, A. P. Jacomini, D. S. Gonçalves, D. F. Back, S. Moura and F. A. Rosa, Org. Biomol. Chem., 2020, Advance Article , DOI: 10.1039/D0OB00319K

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