Copper-catalyzed C–H/N–H annulation of enaminones and alkynyl esters for densely substituted pyrrole synthesis

Abstract

Herein, the copper-catalyzed annulation of enaminones with alkynyl esters for the facile synthesis of different pyrroles with 2,3,4,5-tetrasubstituted structure has been developed. With Cu(OAc)2 as the only catalyst, the tunable...

Recent Advances in Alkenyl sp2 C–H and C–F Bond Functionalizations: Scope, Mechanism, and Applications

“…Interestingly, a broad array of 2-vinyl pyrroles could be synthesized when employing terminal propiolates as coupling partners under modified conditions (Scheme 388d). 625 Meanwhile, efficient and practical synthetic strategies for the homo-and heterocoupling of enamines have been also established for the synthesis of structurally diverse pyrroles in recent years. Specifically, Guan and co-workers in 2016 elaborated a robust approach for the synthesis of a large variety of multisubstituted NH-pyrroles by a K 2 S 2 O 8 -mediated oxidative homocyclization of enamines (Scheme 389a).…”

Facile approach to multifunctionalized 5-alkylidene-3-pyrrolin-2-ones via regioselective oxidative cyclization of 2,4-pentanediones with primary amines and sodium sulfinates

“…As valuable building blocks of high interest to synthetic chemists, enaminones have been widely used as simple starting materials and key intermediates for various transformations in organic synthesis due to their versatile reactive sites and high intrinsic reactivity. 15 Nevertheless, the reactivity profile of enaminones has been explored in a limited manner heavily depending on the use of the ambident nucleophilic sites (N1 and C3) in previous studies. 15 h – l Utilization of alternative modes of reactivity remains a challenging issue, since it requires the regioselective and/or chemoselective transformations of the C(sp 3 )–H bonds.…”

Photoredox-catalyzed regio- & stereoselective C(sp2)–H cyanoalkylation of enamides with cycloketone oximes via selective C–C bond cleavage/radical addition cascade

“…On the other hand, enamides represent pivotal building blocks in organic synthetic chemistry owing to their unique capabilities in the construction of a diverse array of biologically and physiologically prominent lead compounds. 10 Therefore, the regio- and stereoselective β-C(sp 2 )–H functionalization strategies of enamides including olefination, 11 arylation, 12 alkynylation, 13 alkylation, 14 acylation, 15 fluoroalkylation, 16 arylsulfonylation 17 and many other transformations 18 have been at the frontiers in organic synthetic chemistry with rapid and blooming development. Despite those elegant advancements, to the best of our knowledge, the regio- and stereoselective installment of biologically and synthetically crucial cyanoalkyl moieties into enamides remained a compelling challenge.…”