Rationalization of Benzazole-2-carboxylate versus Benzazine-3-one/Benzazine-2,3-dione Selectivity Switch during Cyclocondensation of 2-Aminothiophenols/Phenols/Anilines with 1,2-Biselectrophiles in Aqueous Medium
Tejas M. Dhameliya, Sumit S. Chourasiya, Eshan Mishra, Pradeep S. Jadhavar, Prasad V. Bharatam and Asit K. Chakraborti*
*Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India, Email: akchakrabortiniper.ac.in
T. M. Dhameliya, S. S. Chourasiya, E. Mishra, P. S: Hadhavar, P. V. Bharatam, A. K. Chakraborti, J. Org. Chem., 2017, 82, 10077-10091.
DOI: 10.1021/acs.joc.7b01548 (free Supporting Information)
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Whereas the cyclocondensation of 2-aminothiophenols with 1,2-biselectrophiles such as ethyl glyoxalate and diethyl oxalate in aqueous medium leads to the formation of benzothiazole-2-carboxylates via a 5-endo-trig process contrary to Baldwin’s rule, the reaction of 2-aminophenols/anilines produced the corresponding benzazine-3-ones or benzazine-2,3-diones via a 6-exo-trig process in compliance with Baldwin’s rule.
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