A Convenient Method of Dichlorocarbene Addition to Vinyisilanes

Abstract

In a continuing study of the use of vinylsilanes as intermediates in organic synthesis,¹ we had need of the dichlorocarbene adduct of vinylsilanes. The success of this reaction has been shown to be very reagent-dependent, occurring in only extremely low yield when the chloroform-potassium t-butoxide reagent was used,² but in moderate to good yield with dichlorocarbene derived from the thermolysis of phenyl(bromodichloromethyl)mercury³ in benzene at 80° or (trichloromethyl)trichlorosilane⁴ at 250°. Indeed the desired dichlorocyclopropanation was achieved when cis-1-trimethylsilylhex-1-ene (1)¹ was subjected to the mercurial

reagent to give 1,1-dichloro-2-(n-butyl)-3-trimethylsilylcyclopropane (2)⁵ in 72% conversion (77% yield based on recovered starting material).