54689-97-3Relevant academic research and scientific papers
Solvent-dependent reactivities of acyclic nitrones with β-diketones: Catalyst-free syntheses of endiones and enones
Lasri, Jamal,Gajewski, Grzegorz,Guedes Da Silva, M. Fátima C.,Kuznetsov, Maxim L.,Fernandes, Ricardo R.,Pombeiro, Armando J.L.
experimental part, p. 7019 - 7027 (2012/09/05)
Reactions of the nitrones -O+N(Me)C(H)Ar 1 (Ar=phenyl 1a, 4-methylphenyl 1b, 2,4,6-trimethylphenyl 1c, and anthracen-9-yl 1d) with the cyclic β-diketones 1,3-indandione 2 or barbituric acid 3 in CH 2Cl2, afford the corresponding endiones 2′a-2′d or 3′a-3′d. In contrast, dimedone 4 reacts with 1a or 1b to give the endione 4′a or 4′b and the bis-adduct 4″a or 4″b. Nevertheless, reaction of 4 with 1c or 1d in CH 2Cl2 furnishes only the endione adducts 4′c or 4′d. However, the reaction of 4 with 1a or 1b in methanol gives only 4″a or 4″b, respectively. Among acyclic β-diketones only malonic acid 7 reacts with 1a-1c. Reaction of 7 with 1a in CH2Cl 2 forms cinnamic acid 7″a, whereas in the case of 1b, the endione 7′b and (E)-3-p-tolylacrylic acid 7″b are obtained. The nitrone 1c reacts with 7 in CH2Cl2 to afford the endione 7′c or with acetone yielding (E)-4-mesitylbut-3-en-2-one 8. X-ray analyses are reported for 4′c, 5, and 7″b. In addition, the calculated acidity of the hydrogen at the α-C atom is shown to correlate with the reactivity of the β-diketones with nitrones.
