A Practical Preparation of Highly Versatile N-Acylpyrroles from 2,4,4-Trimethoxybutan-1-amine
摘要:
A novel method for the preparation of N-acylpyrrole is described. The method involves condensation of carboxylic acids with 2,4,4-trimethoxybutan-1-amine, followed by acid-mediated cyclization to form the pyrrole ring. The preparative procedure is highly tolerant of a variety of functional groups.
N-acylpyrroles were synthesized via olefin ring-closingmetathesis of diallylamines and in situ oxidative aromatization in the presence of the ruthenium Grubbs catalyst and a suitable copper catalyst. In the presence of Cu(OTf)2 and CuBr2, the reaction afforded N-sulfonyl- and N-acylpyrroles, respectively, in one pot. Under an oxygen atmosphere, the reaction went smoothly without the need of hydroperoxide
C2-alkenylation of N-acyl pyrroles with alkenes has been described. The acyl unit was found to be an effective chelating group for the activation of aryl C-H bonds ortho to the directing group. The alkenylation reaction of benzoyl pyrroles occurred regioselectively at the C2-position of the pyrrole ring, without touching the benzene ring. The reaction provides exclusively monosubstituted pyrroles under the optimized
C2-arylation of N-acyl pyrroles with arylhalides is developed for the first time using Pd(PPh3)4 as a catalyst in combination with Ag2CO3 under air, which allowed the application of a good compatibility catalytic system. This protocol provides a straightforward method for the preparation of valuable arylated pyrroles in moderate to good yields under the standard conditions with good substrate tolerance
N-酰基吡咯与芳基卤化物的C2-芳基化反应是首次使用Pd(PPh 3)4作为催化剂与Ag 2 CO 3组合在空气中进行的,这使得可应用良好相容性的催化体系。该方案提供了一种简单的方法,可在标准条件下以良好的底物耐受性以中等至良好的产率制备有价值的芳基化吡咯。有趣的是,尽管N-苯甲酰基吡咯反应良好,但使用具有噻吩或呋喃环的底物表明,对于本催化体系,噻吩和呋喃环比吡咯更具反应性。
A Practical Preparation of Highly Versatile <i>N</i>-Acylpyrroles from 2,4,4-Trimethoxybutan-1-amine
A novel method for the preparation of N-acylpyrrole is described. The method involves condensation of carboxylic acids with 2,4,4-trimethoxybutan-1-amine, followed by acid-mediated cyclization to form the pyrrole ring. The preparative procedure is highly tolerant of a variety of functional groups.
Ni-catalyzed direct alcoholysis of N-acylpyrrole-type tertiary amides under mild conditions
作者:Hang Chen、Dong-Huang Chen、Pei-Qiang Huang
DOI:10.1007/s11426-019-9665-5
日期:2020.3
Abstract N-Acylpyrrole-type amides are a class of versatile building blocks in asymmetric synthesis. We report that by employing Ni(COD)2/2,2′-bipyridine (5 mol%) catalytic system, the direct, catalytic alcoholysis of N-acylpyrrole-type aromatic and aliphatic amides with both primary and secondary alcohols can be achieved efficiently under very mild conditions (rt, 1 h) even at gram scale. By increasing