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Enaminones as building blocks in heterocyclic synthesis: New syntheses of nicotinic acid and thienopyridine derivatives
Author(s) -
Abdelkhalik Mervat Mohammed,
Eltoukhy Afaf Mohammed,
Agamy Samia Michel,
Elnagdi Mohammed Hilmy
Publication year - 2004
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.5570410321
Subject(s) - chemistry , thienopyridine , nicotinic agonist , combinatorial chemistry , biochemistry , receptor , aspirin , clopidogrel
Reacting 1,3‐diphenyl‐propan‐2‐one with equimolecular amount of dimethylformamide dimethylacetal afforded the enaminone 4. This when reacted with another equimolecular amount of dimethylformamide dimethylacetal afforded the dienaminone 5. Compound 4 condenses with cyanothioacetamide and with cyanoacetamide to yield 2‐thioxo‐ and 2‐oxo‐pyridine‐3‐carbonitrile derivatives 6a,b respectively. Compound 6a reacted with α‐chloroacetone 8 to yield the thieno[2,3‐ b ]pyridine derivative 10 that cyclized further into 4,7,8‐trisubstituted pyrido[2′,3′:2,3] thieno[4,5‐d]pyrimidine 12. Compound 4 also afforded 2,5,6‐trisubstituted nicotinic acid ethyl ester 13 by reaction with ethyl acetoacetate in acetic acid in the presence of ammonium acetate. The dienaminone 5 reacted with acetic acid, ammonium acetate/acetic acid, phenylhydrazine and 5‐amino‐3‐methylpyrazole yielding 3,5‐diphenyl‐pyran‐4‐one 15a , 3,5‐diphenyl‐1 H ‐pyridin‐4‐one 15b and 1,3,5‐trisubstituted pyridin‐4‐ones 16a‐b.