REGIOSELECTIVE PREPARATION OF 3,4-DIHYDRO ETHYL-2H,6H-[1,3]-THIAZINO[2,3-B]QUINAZOLIN-6-ONES AND HYDRO-3-METHYL-5H-THIAZOLO[2,3-B]QUINAZOLIN-5-ONES AS WELL AS ANALOGOUS POLYCYCLIC PYRIMIDINONE DERIVATIVES FROMCONDENSED 2-ALKENYLTHIOPYRIMIDINE-4(3H)-ONES
P. Wippich et al., REGIOSELECTIVE PREPARATION OF 3,4-DIHYDRO ETHYL-2H,6H-[1,3]-THIAZINO[2,3-B]QUINAZOLIN-6-ONES AND HYDRO-3-METHYL-5H-THIAZOLO[2,3-B]QUINAZOLIN-5-ONES AS WELL AS ANALOGOUS POLYCYCLIC PYRIMIDINONE DERIVATIVES FROMCONDENSED 2-ALKENYLTHIOPYRIMIDINE-4(3H)-ONES, Synthesis, (6), 1996, pp. 741
Acid-catalysed reaction of condensed 2-crotylthiopyrimidinones 3 led r
egioselectively to fused -dihydro-4-methyl-2H,6H-[1,3]thiazinopyrimidi
nones 7. On the other hand, cyclization of 2-allylthio-pyrimidinones 2
under the same conditions resulted in the formation of 2,3-dihydro-3-
methyl-5H-thiazolo-pyrimidinones 4.