ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Theoretical study of the structure of 2-acyl- and 2-methoxycarbonylcycloalkanones

P. Zahradník, Ľ. Václavík, and P. Hrnčiar

Department of Organic Chemistry, Faculty of Natural Sciences, Komenský University, CS-842 15 Bratislava

Abstract:  The most preferred tautomers of 2-formyl-, 2-acetyl-, and 2-methoxycarbonylcyclopentanones, as well as -cyclohexanones, were calculated by means of the quantum chemical CNDO/2 method using a gradient optimization. Where­ as in 2-formyl-, 2-acetyl-, and 2-methoxycarbonylcyclopentanones the keto-exoenol tautomer, stabilized by hydrogen bond, is energetically most advantageous, in 2-formyl- and 2-acetylcyclohexanones derealization of elec­trons occurs due to strong hydrogen bond leading thus to a planar, quasi-aromatic, six-membered system. Not so extensive is derealization in 2-methoxycarbonylcyclohexanone where the resultant optimum structure most approaches to the keto-endoenol tautomer. The results obtained are in agreement with the known experimental findings.

Full paper in Portable Document Format: 381a139.pdf

Chemical Papers 38 (1) 139–144 (1984)