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Pyridine Syntheses. II . Condensation Routes Toward Streptonigrin Ring C
Author(s) -
Robinson J. Michael,
Ahmed Masood,
Alaniz Nicky J.,
Boyles Timothy R.,
Brasher Chris D.,
Floyd Kimberly A.,
Holland Preston L.,
Maruffo Laura D.,
Mcmahan Terry L.,
Middleton Stan,
O'Hara Kevin D.,
Pack Marcia J.,
Reynolds Brandon D.,
Rodriquez Romelia R.,
Sawyer Dennis E.,
Sharp Elena,
Simpson Sharai L.,
Vanlandingham Clint L.,
Velasquez Rebecca S.,
Welch Brian M.,
Wright C. David
Publication year - 1998
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.5570350113
Subject(s) - chemistry , pyridine , ring (chemistry) , yield (engineering) , ketone , acetic acid , ammonium acetate , condensation , ammonium , medicinal chemistry , stereochemistry , organic chemistry , materials science , high performance liquid chromatography , physics , metallurgy , thermodynamics
Alternative complimentary syntheses of penta‐substituted pyridine rings with full regiochemical control of substituents were studied as a method for the synthesis of Streptonigrin ( 1 ). Various α‐substituted acetophenones 2 were reacted with enones 3 in acetic acid/ammonium acetate and air to afford penta‐substituted pyridines 4 . α‐Substituents that could provide a source of exocyclic nitrogen at position 3 of these Steptonigrin ring‐C models proved to be the limiting factor. However, an inverse “3+2+1” cyclocondensation of α‐cyanochalcone 5c with 2‐furyl ethyl ketone ( 6b ) afforded the desired model 6‐(2‐furyl)‐5‐methyl2,4‐diphenyl‐3‐pyridinecarbonitrile ( 4g ) in 75% yield.