Thieno [2, 3-d] Pyrimidine-4-Ones. Part 4.* Directions of Reactions of the 2-Oxo-, -Thioxo-5, 6-Dimethyl-3, 4-Dihydrothieno [2, 3-d] Pyrimidine-4-Ones with Electrophilic Reagents

Abstract

Interaction of 5,6-dimethyl-3,4-dihydrothieno[2,3-d]pyrimidine-4-one (1), -thione(2) with alkylation agents (methyl-, ethyl-, n-propyl-, n-butyl iodides, allylbromide, benzyl chloride) in different conditions (in the presence of catalyst and/or without catalyst) were investigated. It was shown that methyl group in position 5 under action of nitrating mixture (NM) takes place aromatic ipso-substitution reaction or its oxidation up to corresponding carboxylic acid. Directions of reactions depend on nature of substituent in position N-3. It is revealed, that at absence of the substituent in position 3 (compounds 1, 2, 11) the electrophilic ipso-substitution of methyl group by nitro group with formation of 5nitroderivatives took place. It is found, that at interaction of compounds 3, 19 with NM instead of substitution of methyl groups at C-5 go in an expected direction, i.e. there are oxidation of methyl groups. Original Research Article