Regioselective hydrodehalogenation of 3,5-dihaloisothiazole-4-carbonitriles: synthesis of 3-haloisothiazole-4-carbonitriles
摘要:
3,5-Dibromoisothiazole-4-carbonitrile 1 treated with Zn or In dust (5 equiv) and HCO2H undergoes regioselective hydrodebromination to give 3-bromoisothiazole-4-carbonitrile 3 in 70-74% yield. Similarly, 5-bromo and iodo 3-chloroisothiazole-4-carbonitriles 8 and 9 give 3-chloroisothiazole-4-carbonitrile 4 in 77 and 85% yields, respectively. Also hydrodeamination of 5-amino-3-chloroisothiazole-4-carbonitrile 7 using isoamyl nitrite gives the latter in 95% yield. The dibromoisothiazole 1 reacts with Zn dust in either DCO2D or HCO2D to give 3-bromo-5-deuterioisothiazole-4-carbonitrile 10 in 71 and 58% yields, respectively. The 3-bromoisothiazole 3 reacts with cyclic dialkylamines to give the corresponding 2-(dialkylaminomethylene)-malononitriles and not the expected 3-dialkylaminoisothiazole-4-carbonitriles. Finally, the 3-bromoisothiazole 3 is readily converted into both 3-bromoisothiazole-4-carboxamide 19 and the carboxylic acid 20. All products are fully characterized. (C) 2011 Elsevier Ltd. All rights reserved.
Arynes Double Bond Insertion/Nucleophilic Addition with Vinylogous Amides and Carbodiimides
作者:Ran Li、Huarong Tang、Haixing Fu、Hailong Ren、Xuemei Wang、Chunrui Wu、Chao Wu、Feng Shi
DOI:10.1021/jo402754d
日期:2014.2.7
some C═X double bonds, leading to benzannulated four-membered rings. The strain of these rings allow for a ready, spontaneous opening to afford o-quinomethide analogues. Subsequent nucleophilicaddition re-aromatizes the intermediates to achieve ortho-difunctionalization of arynes. In this report, we describe the aryne insertion into the C═C double bonds of vinylogous amides and the C═N double bonds of
Ring Transformation Reactions Starting from 6-Imino-6H-1,3-thiazines
作者:Detlef Briel
DOI:10.3987/com-03-9852
日期:——
Ring transformation reactions of 6-imino-6H-1,3-thiazines (4), 6-imino-6H-1,3-thiazine hydroperchlorates (3), respectively, are initiated under basic conditions by a ring opening of the thiazine nucleous. Two possibilities exist, either intramolecular elimination occurs to give acrylonitriles (5), or addition of a nucleophile (YH) results in the formation of substituted acrylthio-amides (6). The way by which stable products were formed depends on both the functionality of the thiazine, and the reaction conditions. The way 4-->5 produce 1,3-benzoxazines (8), or 1,2,4-dithiazoles (14), respectively. The way 4 --> 6 gives pyrimidinethiones (7), or 1,2-dithioles (17), respectively. Upon treatment of thiazine perchlorates (3) with alkylhalides under basic conditions, acrylonitriles (18) are formed by the way 4 --> 5. Compounds (18) can be transformed to 1,2,4-triazoles (19).