Microwave-assisted zinc chloride-catalyzed synthesis of substituted pyrroles from homopropargyl azides
摘要:
Ligand-free 5-endo-dig cyclization of 1,4- and 1,2,4-substituted but-3-yn-1-yl (homopropargyl) azides in the presence of zinc chloride (usually 20 mol %) in dichloroethane at elevated temperature provides 2,5-di- and 2,3,5-trisubstituted pyrroles in high to moderate yields (91-41%). Both conventional and microwave protocols furnished comparable results. A structure of 2-(4-fluorophenyl)-5-(4-methyl-phenyl)-1H-pyrrole was confirmed by X-ray crystallography. (C) 2008 Elsevier Ltd. All rights reserved.
Copper-Catalyzed Cascade Transformation of Homopropargyl Azides into Trifluoromethylated Nitriles via C–C Cleavage
作者:Shuang Chen、Deng-Yuan Li、Liang-Liang Jiang、Kai Liu、Pei-Nian Liu
DOI:10.1021/acs.orglett.7b00571
日期:2017.4.21
A cascade reaction of homopropargyl azides in the presence of a Cu catalyst was achieved, affording 3-(trifluoromethyl)but-3-enenitriles with good yields and excellent regioselectivity. This reaction appears to be the first direct conversion of homopropargyl azides into trifluoromethylated nitriles. Mechanisticstudies indicate that the transformation proceeds by addition of a CF3 radical to the alkyne
Alternate Mode of Palladium-Catalyzed Alkynyliminium Ion Cyclizations Affording Stereodefined <i>N</i>-Alkyl-3-alkylidenepyrrolidines
作者:Hirokazu Tsukamoto、Mitsugu Shiraishi、Takayuki Doi
DOI:10.1021/ol402685g
日期:2013.12.6
Pd/P(c-C6H11)(3)-catalyzed alkynyliminium ion cyclization in the presence of organoboronic acids affords stereodefined N-alkyl-3-alkylidenepyrrolidines. The distinctive cis-selective addition of the boronic acids and the iminium ions across the alkyne would result from favored 5-exo- or 6-exo-dig cyclization through oxidative addition of the formaldiminium ions to Pd(0).