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.
LO, VECCHIO, G.;CARUSO, F.;RISITANO, F.;FOTI, F.;GRASSI, G., J. CHEM.RES. SYNOP., 1983, N 3, 76-77
作者:LO, VECCHIO, G.、CARUSO, F.、RISITANO, F.、FOTI, F.、GRASSI, G.
DOI:——
日期:——
KI-Catalyzed Oxidative Cyclization of Enamines and <sup><i>t</i></sup>BuONO to Access Functional Imidazole-4-Carboxylic Derivatives
noble-metal-free oxidative cyclization of enamines and tBuONO has been developed. This KI-mediated formal [4 + 1] cycloamination reaction provides a practical strategy for the synthesis of imidazole-4-carboxylic derivatives using tBuONO both as an aminating reagent and oxidant. The reaction features wide substrate scope and good functional tolerance for enamine compounds, even the unactivated ones.
开发了一种用于烯胺和t BuONO的无贵金属氧化环化的简单方案。这种 KI 介导的形式 [4 + 1] 环胺化反应为使用t BuONO 作为胺化试剂和氧化剂合成咪唑-4-羧酸衍生物提供了实用策略。该反应具有广泛的底物范围和对烯胺化合物良好的功能耐受性,即使是未活化的。