Premium
Heterocyclization of Acetamidrazones. I. Synthesis of 1,2,4‐triazolo[4,3‐ a ]pyridines via ring closure of 6‐(2‐acylhydrazino)pyridine intermediates
Author(s) -
Cocco Maria Teresa,
Congiu Cenzo,
Onnis Valentina,
Maccioni Antonio
Publication year - 1991
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570280343
Subject(s) - chemistry , ring (chemistry) , pyridine , closure (psychology) , yield (engineering) , boiling , medicinal chemistry , stereochemistry , organic chemistry , market economy , metallurgy , materials science , economics
The reaction of N 1 ‐acyl‐2‐ethoxycarbonylacetamidrazones with ethyl ethoxymethylenecyanoacetate (EMCA) has been examined. The acetamidrazone 1a reacts with EMCA in boiling dimethyl sulphoxide to give the 1,2,4‐triazolo[4,3‐ a ]pyridin‐3(2 H )‐one 2 in excellent yield. Similarly from the amidrazones 1b‐h the 1,2,4‐triazolo[4,3‐ a ]pyridines 3b‐h were obtained. When the reaction between the amidrazones and EMCA was performed in ethanolic solution, the 6‐(2‐acylhydrazino)‐pyridines 4 were isolated. Ring closure of 4 afforded the 1,2,4‐triazolo[4,3‐ a ]pyridines.