Ring-contraction from benzo[b][1,4]thiazines to benzo[d]thiazolines induced by oxygen

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• 作者：Sheng-Rong Liao¹ ; Yong Tang¹ ; Liang Xu ; Xue-Feng Zhou ; Jun-Feng Wang ; Bin Yang ; Yong-Hong Liu ; ^{yonghongliu@scsio.ac.cn}
• 关键词：Benzo[b][1 ; 4]thiazine ; Benzo[d]thiazoline ; Ring-contraction ; Protic solvent ; Oxygen
• 刊名：Tetrahedron
• 出版年：2017
• 出版时间：5 January 2017
• 年：2017
• 卷：73
• 期：1
• 页码：98-107
• 全文大小：856 K
• 卷排序：73

文摘

An unexpected ring-contraction from benzo[b]pyrazino[1,2-d][1,4]thiazine-1,4-diones (6) to benzo[4,5]thiazolo[3,2-a]pyrazine-1,4-diones (7) has been developed. The preliminary mechanistic studies showed the transformation contained two independent steps: the first step is the formation of a Michael adduct upon the addition of the protic solvent, in the presence of base, to the C-2-C-3 double bond of compound 6, and the second step is a ring-contraction induced by oxygen via the migration of sulfur atom from C-2 to C-3 position. And its scope is also studied.