METALATION REACTIONS .2. PREPARATION OF BIS(TRIMETHYLSILYL)ALLENES FROM ENYNES

Dimetalation of 1,4-enynes was carried out with butyllithium in ether at low temperatures. Treatment of the metalated enynes with trimethylsilyl chloride yielded in all cases 1,3-bis(trimethylsilyl)allenes conjugated to a double bond. In one case a bis(trimethylsilyl)-1,3-enyne with one trimethylsilyl group in a vinylic and the other in an allylic position was obtained as an additional product. Enynes not having aryl substituents gave, after short metalation periods and subsequent silylation, a mixture of monosilyl products in addition to the disilyl derivatives. © 1969.