Reaction of Magnesium Alkylidene Carbenoids with Lithium .ALPHA.-Sulfonyl Carbanions: A Novel Synthesis of Tri- and Tetra-substituted Allenes from 1-Chlorovinyl p-Tolyl Sulfoxides and Sulfones
below -78 degrees C gave magnesium alkylidene carbenoids in about 90% yields. The reaction of the generated carbenoids with lithium alpha-sulfonyl carbanions was found to afford tri- and tetra-substituted allenes. Both cyclic ketones and acyclic ketones were useful in this procedure. However, the 1-chlorovinyl p-tolyl sulfoxides derived from aldehydes gave only rearranged products, acetylenes, under the