Conformational study of 1,4,5,6-tetrahydropyrimidines. Part II: 1(o-nitrophenyl) derivatives

L. R. ORELLI, I. A. PERILLO

Florianópolis, Brasil

Conferencia; 14th International Conference on Physical Organic Chemistry; 1998

CONFORMATIONAL STUDY OF 1,4,5,6-TETRAHYDROPYRIMIDINES. PART II:  1(o-NITROPHENYL) DERIVATIVES.   Liliana R. Orelli and Isabel A. Perillo Departamento de Química Orgánica.  Facultad de Farmacia y Bioquímica.  Universidad de Buenos Aires.  Junín 956 (1113) Buenos Aires.  Argentina               The chemistry of 1,4,5,6-tetrahydropyrimidines has received much interest in the last years, because of their pharmacological properties.  In fact, several drugs containing the tetrahydropyrimidine moiety have been tested as antihelmintic agents and also as M1 selective agonists.  Although many tetrahydropyrimidines have been evaluated as potential therapeutic agents, only few conformational studies concerning the tetrahydropyrimidine system are available in the literature.             In previous work we have discussed ring inversion and pyramidal N-inversion in 1-aryl-1,4,5,6-tetrahidropyrimidines 1 (Ar= p-Cl Ph, R= H, Me, Et, iPr, tBu, Ph).  In addition to those phenomena, in some 1-orthonitrophenyl derivatives, the presence of a bulky substituent at C2 may restrict free rotation around Ar-N bond.             In this communication, the computational chemical study of some 1-o-NO2Ph-2-alkyl-1,4,5,6,-tetrahydropyrimidines (1) together with 1H data are presented.  A comparison is made with with 1,2-diaryl-1,4,5,6-tetrahydropyrimidines.  Computational chemical study was performed using molecular mechanics (MM+) and semiempirical methods (AM1).  Correlations between computational chemical study and nmr data are discussed.                                                                    1