SYNTHESIS OF FUNCTIONALIZED 1-SILYL-SUBSTITUTED DIENES BY REGIOSELECTIVE CYCLOPROPANATION OF 1-SILYL-SUBSTITUTED BUTADIENES WITH DIBROMOCARBENE FOLLOWED BY AG(I)-PROMOTED RING-OPENING OF THE RESULTING DIBROMOCYCLOPROPANES

The reaction of 1-trimethylsilyl-substituted butadienes with dibromoca rbene, generated from CHBr3 and KOH under phase-transfer conditions ga ve, regioselectively, the corresponding cyclopropane adduct. The ring formation occurs at the double bond away from the silyl substituent. A g+-Promoted ring-opening of these cyclopropanes in the presence of dif ferent nucleophiles gave the corresponding functionalized butadienylsi lanes.