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[摘要]：The reaction between 1-methylimidazole, cyano(phenyl) acetylene, and 1-vinylpyrrole-2-carbaldehydes (MeCN, 20-25 degrees C) stereoselectively gives 1-vinylpyrrole-imidazole ensembles with a (Z,Z)-bis(2-cyano-1-phenylvinyl)oxy function in up to 45% yield. Unlike recently reported three-component reaction between imidazoles, electron-deficient acetylenes, and aldehydes affording 1: 1: 1 adducts, in this case two molecules of acetylene are involved to deliver 1: 2: 1 adducts thus representing a novel functionalizaton of the pyrrole-imidazole alkaloid scaffold. The initial zwitterion generated from imidazole and cyano(phenyl) acetylene is thought to be transformed into a carbene, which reacts with pyrrole-2-carbaldehyde. Two subsequent rearrangements of the 1: 1: 1 adduct furnish the intermediate pyrrole-imidazole ensemble, which in its enol form adds to second molecule of cyano(phenyl) acetylene to yield the final products, functionalized pyrrole-imidazole alkaloids. |
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