Regioselective synthesis of novel 4-aryl-2-ethylthio-7-methyl pyrazolo[1,5-a]-[1,3,5]-triazines

Pyrazolo[1,5-a]-[1,3,5]-triazines 6a–d were obtained by an efficient one-step reaction from S,S-diethyl aroyliminodithiocarbonates 4a–d and 5-amino-3-methylpyrazole 5 or by an alternative two-step reaction from 5 and aroyl isothiocyanates 8a–d to give initially the thiourea derivatives 9a–d, which after S-ethylation and cyclization afforded compounds 6a–d. The intermediate 7a isolated from reaction between 4a and 5 permitted us to establish the orientation.