Silicon in Organic Synthesis. 26. Expedient Synthesis of Dicyclopropylideneethane via Functionalized 1-(Trimethylsilyl)cyclopropanes

Article abstract of DOI:10.1021/jo00193a032

Dicyclopropylideneethane (1) has been prepared from two different 1-(trimethylsilyl)cyclopropane derivatives.In the first, aldehyde 4 is coupled in the presence of zerovalent titanium to give olefin 5 which is readily epoxidized.The alternative methodology features conversion of bromide 6 to sulfide 7 and subsequent application of Ramberg-Baecklund methodology to arrive at 5.Treatment of epoxide 9 with tetra-n-butylammonium fluoride delivers allylic alcohol 10 whose conversion to 1 simply requires activation to the chloride and reexposure to fluoride ion.The targetdiene exhibits a proclivity for polymerization when kept as a neat solid.This tendency is reduced in dilute solution under an inert atmosphere and is almost entirely inhibited at -70 deg C.As expected, 1 is a reactive diene in Diels-Alder reactions despite the obvious steric congestion at its bonding centers.