Eco-friendly and Green Synthesis of 2-alkylsulfanyl- 3H-quinazolin-4-one

Reaction of 2-Thioquinazolinone (1) with various alkylating agents like dimethyl sulphate (DMS),
diethyl sulphate (DES) and benzyl chloride (PhCH2Cl) in the presence of K2CO3 as a mild base, by a
simple physical grinding, microwave irradiation, and PEG-600 under solvent-free conditions for 10-15
min at RT, followed by processing, gave respectively 2-methylsulfanyl-3H-quinazolin-4-one (2a, i.e.,
R=CH3), 2-ethylsulfanyl-3H-quinazolin-4-one (2b, i.e., R=C2H5) and 2-benzyl sulfanyl-3H-quinazolin-
4-one (2c, i.e., R=PhCH2Cl). It appears from this study that Green syntheses such as solid phase
synthesis (physical Grinding) and Micro wave Irradiation gives better yields, quality and in less
reaction time the products over conventional methods involving green solvents like ethanol, PEG-600
etc. The entire sequences of reactions have been carried out using eco-friendly solvents and green
conditions.