Pyridine Syntheses. II. Condensation Routes Toward Streptonigrin Ring C

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...

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Published in:Journal of heterocyclic chemistry 1998-01, Vol.35 (1), p.65-69
Main Authors: 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
Format: Article
Language:English
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Summary: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.
ISSN:0022-152X
1943-5193
DOI:10.1002/jhet.5570350113