42455-41-4Relevant academic research and scientific papers
Ring-contraction of hantzsch esters and their derivatives to pyrrolesviaelectrochemical extrusion of ethyl acetate out of aromatic rings
Liu, Xu,Liu, Chang,Cheng, Xu
, p. 3468 - 3473 (2021/05/21)
Electrochemical ring-contraction of HEs and theirs pyridine derivatives is developed to obtain polysubstituted pyrroles. This process provides an orthogonal utilization of Hantzsch esters for the well-documented application as side chain or hydrogen donors. The formal transformation shows an extrusion of ethyl acetate out of the pyridine ring in a single step. In addition to the novel transformation, we also discovered the Lewis acid's intermolecular control of regioselectivity during an intramolecular electrochemical process. The reaction provides a number of polysubstituted pyrroles that have never been accessed, including pharmaceutical intermediates and photoswitches. An unusual 4-electron continuous reduction drives the unprecedented anionic dearomatization/ring-contraction/rearomatization pathway.
Chemo-Enzymatic Synthesis of Pyrazines and Pyrroles
Xu, Jin,Green, Anthony P.,Turner, Nicholas J.
supporting information, p. 16760 - 16763 (2018/11/27)
Herein we report the biocatalytic synthesis of substituted pyrazines and pyrroles using a transaminase (ATA) to mediate the key amination step of the ketone precursors. Treatment of α-diketones with ATA-113 in the presence of a suitable amine donor yielded the corresponding α-amino ketones which underwent oxidative dimerization to the pyrazines. Selective amination of α-diketones in the presence of β-keto esters afforded substituted pyrroles in a biocatalytic equivalent of the classical Knorr pyrrole synthesis. Finally we have shown that pyrroles can be prepared by internal amine transfer catalyzed by a transaminase in which no external amine donor is required.
One-pot three-component synthesis of tetrasubstituted N - H pyrroles from secondary propargylic alcohols, 1,3-dicarbonyl compounds and tert-butyl carbamate
Cadierno, Victorio,Gimeno, Jose,Nebra, Noel
experimental part, p. 233 - 236 (2010/04/27)
(Chemical Equation Presented) Several tetrasubstituted N - H pyrroles, functionalized with ester or ketone groups at C-3 position, were prepared by one-pot coupling of secondary propargylic alcohols with 1,3-dicarbonyl compounds and tert-butyl carbamate,
One-pot three-component catalytic synthesis of fully substituted pyrroles from readily available propargylic alcohols, 1,3-dicarbonyl compounds and primary amines
Cadierno, Victorio,Gimeno, Jose,Nebra, Noel
, p. 9973 - 9981 (2008/09/17)
A simple and highly efficient method for the preparation of fully substituted pyrroles, from readily accessible secondary propargylic alcohols, 1,3-dicarbonyl compounds and primary amines, has been developed. The one-pot multicomponent reaction, which is catalysed by the system [Ru(μ3- 2C3H4Me)(CO)(dppf)][SbF6]/CF3CO 2H (dppf : 1,1′-bis(diphenylphosphanyl)ferrocene), involves initial propargylation of the 1,3-dicarbonyl compound promoted by CF 3CO2H and subsequent condensation between the resulting y-keto alkyne and the primary amine to afford a propargylated β-enamino ester or ketone, which undergoes a ruthenium-catalysed 5-exo-dig annulation to form the final pyrrole.
