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Reaction of 3-Cl/OMe-Substituted 5-Nitrobenzisothiazoles with Hydrazine: Structural and Computational Evidence for Rearrangement Pathways Implicating Intramolecular Formation of Pivotal Meisenheimer Complexes.
Lin, Zheng Sonia; Tong, Xing; Patrick, Brian; Kennepohl, Pierre; Grierson, David S.
Afiliação
  • Lin ZS; Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
  • Tong X; Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
  • Patrick B; Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
  • Kennepohl P; Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
  • Grierson DS; Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
J Org Chem ; 86(9): 6381-6389, 2021 05 07.
Article em En | MEDLINE | ID: mdl-33852799
In projected structure-activity relationship studies of the novel diheteroarylamide-based anti-HIV agent 2 (1C8), one objective was to evaluate the influence of incorporating the central amide motif in 2 into a five-membered pyrazolone ring, as found in 3. It was envisaged that compound 3 could be prepared through reaction of 3-hydrazino-5-nitrobenzisothiazole 5 with the methyl ester of 4-chloropyridine-3-carboxylic acid, followed by N-methylation of the pyridine nitrogen. However, the reaction of 3-methoxyl-5-nitrobenzisothiazole with hydrazine resulted in formation of ring-opened hydrazonate product 18. In the corresponding reaction with 3-chloro-5-nitrobenzisothiazole, a different rearrangement product 19 was formed, in which two 2,1-benzisothiazole units are joined by a sulfur bridge. Meisenheimer complex formation, favored by the presence of the 5-nitro substituent on the benzisothiazole ring, was postulated to be a key feature in the formation of these deep-seated rearrangement products. Support for the proposed formation of the pivotal Meisenheimer complexes and their subsequent evolution to the observed products in which the benzisothiazole sulfur atom is either expelled or maintained in the isomeric 2,1-benzisothiazole system was obtained by density function theory calculations.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Ácidos Carboxílicos / Amidas Idioma: En Ano de publicação: 2021 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Ácidos Carboxílicos / Amidas Idioma: En Ano de publicação: 2021 Tipo de documento: Article