A versatile synthesis of pyrrolo-, furo- and thienopyridines via photocyclization of 3-amino-2-alkene imines in an acid medium

C-Vinylpyrroles as Pyrrole Building Blocks

“…103 UV irradiation of 2-pyrrolylvinylimines 295a,b in an acidic medium (54% HBF 4 ether solution, Hg lamp, 125W, 25-30 h) in anhydrous MeOH gives 1-methyl-7-(R 1 -amino-5-R 2 -pyrrolo[3,2-b]pyridines) 296a,b (Scheme 109). 104 Unexpectedly, under analogous conditions, 3-pyrrolylvinyl imine 295c cyclizes into 1,6-diphenylpyrrolo[3,2-c]pyridine 297 (Scheme 110). 104 Seemingly, the RORC mechanism involves a pyrrole ring-opening step to form intermediate 298.…”

Base-Promoted Transannulation of Heterocyclic Enamines and 2,3-Epoxypropan-1-ones: Regio- and Stereoselective Synthesis of Fused Pyridines and Pyrroles

“…A survey of the literature revealed that substantial synthetic methods for the formation of functional furo­[3,2- b ]­pyridines have been developed, which involved carbanionic ring closure, photocyclization of 3-furanyl-3-aminoalkene imines, heteroaromatic C-H insertion of alkylidene­carbenes, metal-catalyzed heteroannulation of alkynes, and other methods . Nevertheless, most of these approaches suffered from many drawbacks such as a limited substrate scope, multistep sequences, metal catalysts, and laborious workup.…”

Synthesis and Antibacterial Activity of Thiophenes

“…They have been shown to have interesting biological properties such as anticancer, [1] antiviral, [2] antitumor, [3] anti-inflammatory, [4] and antimicrobial. [5] Starting from thiophene derivatives, many thieno-fused bicyclic compounds such as thienopyridines, [6] thienopyrimidines, [7] and thienopyrroles [8], [9] have been synthesized. El-Saghier et al [10], [11] have reported the syntheses and reactions of various thiophenes and fused thiophenes via ketene S,S-and N,S-acetals.…”