Iodine-Mediated Cyclization of Enamines to Imidazole-4-Carboxylic Derivatives with Sequential Removal of Nitrogen Atoms from TMSN<sub>3</sub>
作者:Peng Gao、Huaijuan Chen、Zi-Jing Bai、Sheng Zhang、Mi-Na Zhao、Desuo Yang、Yingchun Li、Jiangwei Zhang、Xiaomei Wang
DOI:10.1021/acs.joc.1c01145
日期:2021.8.6
iodine-mediated oxidative [4+1] cyclization of enamines with TMSN3 for the synthesis of 2,5-disubstituted imidazole-4-carboxylic derivatives has been developed. The mechanistic studies revealed that the reaction proceeds through a sequential removal of two nitrogen atoms from TMSN3. The synthetic utility was further demonstrated with a gram-scale reaction and various derivatization transformations of the products
A novel ring transformation/desulfurization of substituted 2-methyl-1,2,4-thiadiazolium salts 2 provides a versatile entry to imidazoles 3 with a variety of substituents. Simple one-pot procedures combine the preparation of starting 1,2,4-thiadiazolium salts 2 from N-(thiocarbonyl)-N'-methylamidines 1 or 1,2,4-dithiazolium triiodides 6 with the ring transformation/desulfurization to the imidazoles 3. Alternatively, N-(thiacarbonyl)-N'-methylamidines 1 can be transformed to imidazoles 3 or to 1-substituted imidazoles 5 via S-methylation and elimination of methylthiol. In the same manner, a new entry to 4H-imidazoles 8 could be developed.