Synthesis of 3-methyl-5-(hetaryl)-2,4-pentadienoic acids from aldehydes

✍ Scribed by K. I. Kuchkova

• Publisher: Springer US
• Year: 1991
• Tongue: English
• Weight: 362 KB
• Volume: 27
• Category: Article
• ISSN: 0009-3122
• DOI: 10.1007/bf00473998

✦ Synopsis

Reaction of 4-(2-, 3-, 4-pyridyl, or 2-quino?yl)but-3-en-2-ones with carbethoxymethylenetriphenylphosphor. ane and subsequent hydrolysis gives 3-methyl-5-(2-, 3-, 4-pyridyl, or 2-quinolyl)-2,4-pentadienoic acids and also 3-methyl-4-(2-, 4-pyridyl-, or 2-qumo!ylmethyl)but-2-en-4-olides as products of cyclization of the corresponding pentadienoic acids.

We have previously synthesized E,E-3-methyl-5-(3-indolyl)-2,4-pentadienoic acid V. At low concentration in a series of green crops this has high antitranspirational activity comparable to abscisic acid which is a natural regulator of water balance in plants [1]. In a search for novel organic compounds with similar activity we have synthesized the pentadienoic acids Vla-d containing a pyridine or quinoline ring. The o~,fl-unsaturated ketones IIa-d were prepared from the aldehydes Ia-d according to [2] and used in a Wittig condensation with carbethoxymethylenetriphenylphosphorane III to give a mixture of the Z,E-and E,E-isomers of the ethyl 2,4-pentadienoates IVa-d. Hydrolysis with KOH gave the acids VIa-d. In the case of IVb the corresponding, stable Z,E-and E,E-isomeric acids of VIb were separated.