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Electrophilic Cyclization of N ‐Alkynyl‐2‐(organochalcogen)imidazoles: An Alternative Access to Imidazo[2,1‐ b ]chalcogenazoles
Author(s) -
Grimaldi Tamíris B.,
Godoi Benhur,
Roehrs Juliano A.,
Sperança Adriane,
Zeni Gilson
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201201692
Subject(s) - chemistry , regioselectivity , electrophile , chalcogen , combinatorial chemistry , medicinal chemistry , catalysis , stereochemistry , organic chemistry
We present here a practical synthesis of multifunctional imidazo[2,1‐ b ]chalcogenazoles through electrophilic cyclization of N ‐alkynyl‐2‐(organochalcogen)imidazoles. The cyclization reaction proceeded cleanly and smoothly under mild reaction conditions in the presence of air. The methodology was highly regioselective: In a competition between the chalcogen and oxygen atoms, only S‐, and Se‐heterocycles were obtained. The resulting imidazo[2,1‐ b ]chalcogenazoles proved to be versatile as precursors for the synthesis of more highly functionalized imidazoselenazoles through copper‐catalyzed cross‐coupling reactions with arene‐ and alkanethiols, leading to Ullmann‐type products in good yields.