Condensed 1,3-benzothiazinones. 1. Facile synthesis of 2-amino-1,2,4-triazolo[5,1-b][1,3]-benzothiazin-9-one |
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Authors: | Kang-Chien Liu Bi-Jane Shih Ji-Wang Chern |
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Abstract: | Treating 2-mercaptobenzohydrazide ( 1a ) with cyanogen bromide gave 3-amino-2-imino-3,4-dihydro-2.H-1,3-benzothiazin-4-one ( 2a ). This compound underwent further cyclocondensation with a second molecule of cyanogen bromide or S-methylisothiourea sulfate to afford the biologically interesting 2-amino-1,2,4-triazolo-5,1-b]1,3]benzothiazin-9-one ( 3c ). Compound 3c could also be prepared directly from 1a by treating with excess amount of cyanogen bromide in more satisfactory yield. |
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