Addition of 1,3-dicarbonyl compounds to terminal alkynes catalyzed by a cationic cobalt(<scp>iii</scp>) complex
作者:Mohan Chandra Sau、Manish Bhattacharjee
DOI:10.1039/d0ra05923d
日期:——
The Nakamura reaction using a cationic cobalt(III) complex, [Cp*Co(CH3CN)3][SbF6]2 as the catalyst under neutral and aerobic conditions at 110 °C has been described. In solution, the complex is expected to lose a hemilabile acetonitrile ligand to produce a highly electron-deficient cobalt(III) center, and the Lewis acidic nature of the cobalt center has been exploited for the enolization of the dicarbonyl
已经描述了使用阳离子钴( III ) 配合物[Cp*Co(CH 3 CN) 3 ][SbF 6 ] 2作为催化剂在中性和有氧条件下在110 °C 下的Nakamura 反应。在溶液中,该配合物预计会失去半可溶的乙腈配体,从而产生高度缺电子的钴(III) 中心,并且钴中心的路易斯酸性已被用于二羰基化合物的烯醇化。1,3-二羰基化合物与炔烃反应得到相应的烯基衍生物。然而,苯乙炔及其衍生物与 β-酮酯反应得到相应的三联苯化合物。已经基于原位LCMS 测量提出了反应机制的细节。
Manganese-Catalyzed Construction of Tetrasubstituted Benzenes from 1,3-Dicarbonyl Compounds and Terminal Acetylenes
Treatment of beta-keto esters with terminal acetylenes in the presence of a catalytic amount of a manganese complex, MnBr(CO)(5), and molecular sieves, gave multisubstituted aromatic compounds in good to excellent yields. This reaction employs [2 + 2 + 2] cycloaddition of beta-keto esters and 2 equiv of terminal acetylenes with dehydration. In the case of a 1,3-diketone, the corresponding acetophenone derivative and its deacylated compound can be synthesized selectively.