Reaction of esters of 2-arylcyclo-propanecarboxylic acids with nitrous acid. Synthesis of aryl-substituted 3-ethoxycarbonyl-4,5-dihydroisoxazoles and 3-ethoxycarbonylisoxazoles

• Published in: Chemistry of heterocyclic compounds (New York, N.Y. 1965) N.Y. 1965), 2009-05, Vol.45 (5), p.595-605
• Main Authors: Kadzhaeva, A. Z, Trofimova, E. V, Fedotov, A. N, Potekhin, K. A, Gazzaeva, R. A, Mochalov, S. S, Zefirov, N. S
• Format: Article
• Language: English
• Subjects: 5-aryl-3-ethoxycarbonyl-4,5-dihydroisoxazoles; 5-aryl-3-ethoxycarbonylisoxazoles; Chemistry; Chemistry and Materials Science; ethyl esters of 2-arylcyclopropanecarboxylic acids; insertion of the nitrosyl cation into the cyclopropane ring; Organic Chemistry; Pharmacy
• ISSN: 0009-3122; 1573-8353
• DOI: 10.1007/s10593-009-0315-6

Esters of 2-arylcyclopropanecarboxylic acids react with nitrous acid generated in situ with regioselective insertion of the nitrosyl cation into the cyclopropane ring. Depending on the substrate/nitrosylating agent ratio, the reaction proceeds with the formation of either aryl-substituted 3-ethoxycarbonyl-4,5-dihydroisoxazoles or the corresponding isoxazoles. The nature and position of the substituents in the aromatic ring of the starting 2-arylcyclopropanecarboxylic acid esters affect the reaction rate but have no effect on the regioselectivity of the attack by the nitrosyl cation on the three-membered ring. A dependence of the reactivity of isomeric substrates on their stereochemistry and position of the nitro group in the aromatic ring is noted for 2- and 4-nitrophenyl derivatives of esters of cis- and trans-2-arylcyclopropanecarboxylic acids.