Investigation the chemical reactivity of positions N‐3, C‐5 and C 6 ‐methyl group in biginelli type compounds and synthesis of new dihydropyrimidine derivatives

The compounds 5‐ethoxycarbonyl‐1,6‐dimethyl‐4‐(3‐nitrophenyl)‐3,4‐dihydropyrimidin‐2(l H )‐one (5) and 5‐ethoxycarbonyl‐1‐phenyl‐6‐methyl‐4‐(3‐nitrophenyl)‐3,4‐dihydropyrimidin‐2(l H )‐one (1) were prepared by the Biginelli condensation method and they converted to eight N‐3 substituted dihydropyrimidines using NaH and various electrophiles (ClCO 2 Et, TsCl, Ac 2 O, AcCl and PhCOCl). Compound (1) was mono‐brominated at the C 6 ‐methyl group using bromine solution. Reaction of the bromo derivative with amino nucleophiles such as methyl amine and cyclohexyl amine produced two pyrrolo‐pyrimidine derivatives. All the compounds except 5‐ethoxycarbonyl‐1‐phenyl‐6‐methyl‐4‐(3‐nitrophenyl)‐3,4‐dihydropyrimidin‐2(l H )‐one ( 4 ) were purified by recrystallization methods. The structure of all the new compounds was confirmed using FT‐ir, 1 H nmr, 13 C nmr spectral and elemental analyses methods.