Ab initio and Semiempirical Conformational and Configurational Analysis of N-2-(1,4-Dioxane)-N'-(4-methylbenzenesulfonyl)-O-(4-methylphenoxy)isourea

H.A. Dabbagh^a,*, A.R. Najafi Chermahini^a, A.R. Modarresi-Alam^b and A. Teimouri^a
aDepartment of Chemistry, Isfahan University of Technology, Isfahan, 8415483111, Iran
^bDepartment of Chemistry, Sistan & Baluchestan University, Zahedan, 98135, Iran

(Received 15 July 2005, Accepted 24 December 2005)

      The conformational, configurational behavior and the structure of N-2-(1,4-dioxane)-N'-(4-methylbenzenesulfonyl)-O-(4-methylphenoxy) isourea 1 has been studied using ab initio and semiempirical calculations (AM1 and PM3). The endo-anomeric effect and hydrogen bonds control the population of dioxane ring conformers or anomers but not the configuration interconversion of the imine of imidoyl moiety. Ab initio and AM1 and PM3 calculations demonstrate that the dioxane ring adopts a chair conformation, that the imidoyl amino group prefers an axial conformation and that the tosyl and tolyl groups about the C=N bond retain an E configuration. The computational analysis of 1 complements the X-ray findings.

Keywords: Anomeric effect, Conformational analysis, Configurational analysis, ab initio, AM1, PM3