Synthesis, Dft Study and the Eschenmoser Sulfide Contraction of 1,2,3,4-Tetrahydropyrimidine Derivatives

Abstract

5-Substituebenzoyl-4-aryl-6-substituephenyl-1,2,3,4-tetrahydro-2-(thioxo, oxo and imino) pyrimidines (4a-d) were synthesized via multicomponent cyclocondensation reaction. 7-Benzoyl- 8-phenyl-6-(4-carboxyphenyl)-2,3-dihydropyrimido[2,1-b][1,3] thiazin-4(6H)-one (5), 6-benzoyl- 2-methyl-7-phenyl-5-(4-carboxyphenyl)-3-oxo-2,3-dihydro-5H-thiazolo[ 3,2-a] pyrimidine (6) and 6-benzoyl-7-phenyl-5-(4-carboxyphenyl)-3-oxo-2,3-dihydro-5H-thiazolo[3,2-a] pyrimidine (7) were synthesized via reactions of starting compound 4e [1] and appropriate reagent compounds. When 4e was treated with alpha-bromoester in 1,4-dioxane (1/10 mL) it was resulted like the Eschenmoser sulfide contraction and compounds 8 was obtained. This method generally requires tertiary phosphine but instead of it we used pyridine as a catalyst. In addition, all synthesized pyrimidine derivatives have been optimized geometrically with DFT in Gaussian at the B3LYP/6-31G(d, p) level in order to obtain information about the 3D geometries and electronic structures.