Regioselectivity of electrophilic attack on 4-methyl-1-thioxo-1,2,4,5-tetrahydro[1,2,4]triazolo[4,3-a]quinazolin-5-one - Part 2: Reactions on nitrogen atom
W. Fathalla et al., Regioselectivity of electrophilic attack on 4-methyl-1-thioxo-1,2,4,5-tetrahydro[1,2,4]triazolo[4,3-a]quinazolin-5-one - Part 2: Reactions on nitrogen atom, MOLECULES, 5(12), 2000, pp. 1210-1223
The regioselectivity on a cyclic thioamide group towards different electrop
hiles was studied on the model compound 4-methyl-1-thioxo-1,2,4,5-tetrahydr
o[1,2,4]triazolo [4,3-a]quinazolin-5-one 1. The examined compound 1 reacts
with alkyl halides, amines in the presence of formaldehyde, acyl halides an
d compounds having activated double bonds to afford the N-substituted deriv
atives 2, 3 and 6. The regioselective reactions on nitrogen atom are due to
strong Coulombic attraction. The reaction of 1 with amines in the presence
of hydrogen peroxide afforded the aminolysis product 4. Compounds 1-6 were
identified by FTIR, 1H MMR, 13C NMR, and mass spectroscopy.