Haloacetylated enol ethers: 15. Study of the regiochemistry of the cyclo-condensation of beta-alkoxyvinyl trihalomethyl ketones with N-methyl thiourea

A study of the regiochemistry of the cycle-condensation reaction of beta -a lkoxyvinyl trihalomethyl ketones with an unsymmetric dinucleophile N-methyl thiourea to afford a series of 1-methyl-3-(4,4,4-trifluoro[chloro]-3-oxo-1 -butenyl)thioureas and the corresponding N-methyl pyrimidinethione derivat ives is reported. The absolute assignment of the position of the N-methyl g roup in the pyrimidine ring was obtained through a nmr study based on two d imensional HMBC and NOESY experiments.