Reagent-Controlled Divergent Synthesis of 2-Amino-1,3-Benzoxazines and 2-Amino-1,3-Benzothiazines
V. P. Rama Kishore Putta, Nagaraju Vodnala, Raghuram Gujjarappa, Ujjawal Tyagi, Aakriti Garg, Sreya Gupta, Prasad Pralhad Pujar* and Chandi C. Malakar*
*Department of Chemistry, CHRIST, Bangalore 560029; Department of Chemistry, NIT Manipur, Langol, Imphal 795004, Manipur, India, Email: prasad.pujarchristuniversity.in, cmalakarnitmanipur.ac.in
V. P. R. K. Putta, N. Vodnala, R. Gujjarappa, U. Tyagi, A. Garg, S. Gupta, P. P. Pujar, C. C. Malakar, J. Org. Chem., 2020, 85, 380-396.
DOI: 10.1021/acs.joc.9b02384 (free Supporting Information)
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Treatment of various 2-amino-arylalkyl alcohols with isothiocyanates afforded thiourea intermediates, which were reacted in situ with molecular iodine in the presence of triethylamine to give 2-amino-4H-1,3-benzoxazines. The reaction of the thiourea intermediates with T3P as mild cyclodehydrating reagent and triethylamine as the base provides 2-amino-4H-1,3-benzothiazines.
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