Ethynylation of pyrroles with 1-acyl-2-bromoacetylenes on alumina: a formal ‘inverse Sonogashira coupling’
作者:Boris A. Trofimov、Zinaida V. Stepanova、Lyubov’ N. Sobenina、Al’bina I. Mikhaleva、Igor A. Ushakov
DOI:10.1016/j.tetlet.2004.06.114
日期:2004.8
Pyrroles are cross-coupled with 1-acyl-2-bromoacetylenes on the surface of Al2O3 at room temperature under solvent-free conditions to afford 2-(acylethynyl)pyrroles with 100% regioselectivity and in good yields, thus representing the first example of a palladium-, copper-, base-, and solvent-free (‘green’) ethynylation of pyrroles, which can be considered a formal ‘inverse Sonogashira coupling’. Given
吡咯在室温下于无溶剂条件下与Al 2 O 3表面上的1-酰基-2-溴乙炔进行交叉偶合,从而制得具有100%区域选择性和高收率的2-(酰基乙炔基)吡咯,这是第一个吡咯的钯,铜,碱和无溶剂(“绿色”)乙炔化的例子,可以认为是形式上的“ Sonogashira逆偶联”。考虑到对官能化的吡咯和乙炔的兴趣,对于酰基卤代乙炔在吡咯和乙炔化学中的作用,这种新的简便且环保的交叉偶联应该引起人们的极大兴趣。
Silica-Assisted Reactions of Pyrroles with 1-Acyl-2-bromoacetylenes
作者:Lubov’ N. Sobenina、Zinaida V. Stepanova、Al’bina I. Mikhaleva、Igor’ A. Ushakov、Nina N. Chipanina、Valentina N. Elokhina、Vladimir K. Voronov、Boris A. Trofimov
DOI:10.1055/s-2004-831244
日期:——
Pyrroles react with 1-acyl-2-bromoacetylenes at room temperature on silica to give 2-acyl-1,1-di(pyrrol-2-yl)ethenes as major products in yields of up to 60%. Under reaction conditions employed, the intermediates (E)-2-(2-acyl-1-bromoethenyl)pyrroles (3-11% isolated yields) either readily exchange the bromine atom for the pyrrole molecule or eliminate HBr to afford 2-(2-acylethynyl)pyrroles, which can be isolated in 9-22% yields by chromatography of the reaction mixture on Al2O3.