Triethyloxonium tetrafluoroborate mediated addition reaction of unsaturated organosilanes to squaric acid esters

Article abstract of DOI:10.1055/s-1995-3944

Squaric acid esters were treated with triethyloxonium tetrafluoroborate at room temperature to produce ethoxycarbenium ion species, and subsequent addition of trimethylsilyl cyanide (TMSCN) to this intermediate at 0°C afforded O-ethyl cyanohydrins in fair to good yields. In a similar manner, the ester reacted effectively with silyl enol ether and silyl ketene acetal to give the corresponding O-ethylated addition products. On the other hand the reaction with allylsilanes preferred the formation of 1:2 adducts.