4-amino-6-methyl- 1,2,4-triazine-3(2h)-thione-5-0ne (1) was condensed with propargyl bromidein the presence of sodium rnethoxide to afford 3-propargylmercapto- 4-arnino-6-rnethyl-1,2,4-triazin-5-one(2) . transformation of the latter to 8-dihydro- 3-methyl-7-methylene-4-oxo-6h-[1,2,4]triazino [3,4-b] [1,3,4] thiadiazine (3) was performed under the condition of palladium (ii) salt. ring closure o...

A catalytic amount of tin(IV) chloride catalyzed formal [4+2] cycloaddition reaction of di-tert-butyl 2-ethoxycyclobutane-1,1-carboxylate with ketones or aldehydes to give diethyl 6-ethoxydihydro-2H-pyran-3,3(4H)-dicarboxylates, whereas two equivalents of trimethylsilyl triflate promoted tandem [4+2] cycloaddition and lactonization to afford 3-oxo-2,6-dioxabicyclo[2.2.2]octane-4-carboxylate est...