Two-Component Approach Toward a Fully Substituted N-Fused Pyrrole Ring

Abstract

An efficient two-component palladium-catalyzed arylation/cyclization cascade approach toward a variety of N-fused pyrroloheterocycles has been developed. This transformation proceeds via the palladium-catalyzed coupling of aryl halides with propargylic esters or ethers followed by the 5-endo-dig cyclization leading to highly functionalized pyrroloheterocycles in good to excellent yield.

Cycloisomerization of Pyridine‐Substituted Propargylic Alcohols or Esters To Construct Indolizines and Indolizinones

“…(Hetero)aryl metal intermediates probably played an important role during the metal-salt-catalyzed cycloisomerization of pyridine-containing propargylic esters (Scheme 4), and the alkenyl group in the five-membered ring could be further activated. Gevorgyan subsequently reported the intermolecular [12] (Scheme 5) and intramolecular [13] (Scheme 6, below) palladiumcatalyzed coupling of aryl halides with propargylic esters or ethers followed by 5-endo-dig cyclization, leading to fully substituted N-fused pyrroloheterocycles in good to excellent yields. The easily accessible pyridine-containing propargylic esters 3 were first subjected to palladium-catalyzed arylation/cyclization.…”

Palladium-Catalyzed Intramolecular Carbopalladation/Cyclization Cascade: Access to Polycyclic N-Fused Heterocycles

“…This cascade carbopalladation/cyclization approach is complementary to the previously developed methods 10,11,14 toward multi-substituted N-fused heterocycles.…”

“…We have recently reported a two-component coupling methodology toward fully substituted N-fused heterocycles. 9,10 Although quite general with respect to the heterocyclic core, this approach is limited to the synthesis of bicyclic and tricyclic heteroaromatic molecules only (eq 1). Herein, we report a novel Pd-catalyzed arylation cyclization cascade that allows for easy assembly of various tetra-…”

The Synthesis of Aromatic Heterocycles from Propargylic Compounds

“…One of the possible ways to synthesize such compounds was developed by Gevorgyan and co-workers [29] in 2010. They found that treatment of 2-pyridylsubstituted propargylic acetates and its derivatives 134 with ArI 135 (1.5 equiv) and [PdCl 2 A C H T U N G T R E N N U N G (PPh 3 ) 2 ] (5 mol %) in N,N-dimethylformamide (DMF) at 120 8C for 4 h provides 1,2,3-trisubstituted indolizines 136 in high yield (Scheme 36).…”