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Please login or sign up for a free trial to access the full content. Method 9: From But-2-ynedinitrile or But-2-ynediamide

DOI: 10.1055/sos-SD-011-00685

Brown, D. W.; Sainsbury, M.Science of Synthesis, (200211542.

The addition of hydrogen bromide to but-2-ynedinitrile (177) in liquid sulfur dioxide/diethyl ether at 30 to 40°C leads to 2-bromo-3-(bromosulfanyl)butenedinitrile (178), which spontaneously cyclizes to 3,4-dibromoisothiazole-5-carbonitrile (179) in 35% yield (Scheme 58).[‌202‌,‌203‌] An identical reaction with but-2-ynediamide (180) affords 4-bromo-3-hydroxyisothiazole-5-carboxamide (181) in 44% yield.[‌203‌,‌204‌]

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