Cyclopropanation and carbonyl olefination utilizing 2-(alk-1-yn-1-yl)-2-(trialkylsilyl)-1,3-dithianes via regioselective generation of titanium alkynylcarbene complexes

摘要

CP2Ti[P(OEt)(3)](2)-promoted reactions of 2-(alk-1-yn-1-yl)-2-(trialkylsilyl)-1,3-dithianes (RS)(2)C(Si)C&3bond; CR with terminal olefins and carbonyl compounds produced (trialkylsilylethynyl)cyclopropanes and 1-(trialkylsilyl)alk-3-en-1-ynes, respectively. These compounds were suggest to be produced via the formation of intermediary titanium alpha-(trialkylsilylethynyl)carbene complexes CP2Ti=C(R)C&3bond; CSi in preference to their regioisomers, alpha-(trialkylsilyl)alkynylcarbene complexes CP2Ti=C(Si)C&3bond; CR.