Synthesis and cycloadditions of 1-[(tert-butyldimethylsilyl)oxy]alkenyl isocyanates

1-[(tert-Butyldimethylsilyl)oxy] alkenyl isocyanates 1a and 1b have been conveniently prepared from acetyl or propionyl chloride, silver cyanate and tert-butyldimethylsilyl triflate in the presence of triethylamine. They react with electron-deficient acetylenic dienophiles or with tosyl cyanide to give highly functionalised pyridines or derivatives of uracil or thymine in moderate yields. They also cycloadd with 1-(diethylamino)prop-1-yne, an electron-rich dienophile, to yield glutaconimides and pyridine derivatives.