C Bond Formation using Organosilanes

C—C Bond Formation using Organosilanes. Under catalysis by TiCU, allylsilanes transfer the allyl group, with rearrangement, to ketones, a/3-unsaturated ketones (conjugate addition), and quinones (initially giving the carbonyl addition product which then further rearranges to the 2-allyl-l,4-hydroquinone). But-3-enyl-silanes react with acid chlorides to yield cyclopropylmethyl ketones [reaction (3)) under similar conditions. 

Alkylsilanes react with acid chlorides under catalysis with AICI3 to give unsym-metrical ketones.Compound (45) is obtained by reaction of 5-tri-methylsilylcyclopentadiene with dichloroacetyl chloride in the presence of tri-ethylamine, and it may be converted into prostaglandins or into loganin aglycone acetate (46), by subsequent modifications. Compounds (47) and (48) are obtained from photochemical cycloadditions of alkynylsilanes, RC=CSiMe3, with cyclopent-2-enone.  

Metallated allyltrimethylsilane is a /8-acylcarbanion equivalent, since it reacts at the y-position to give an alkenylsilane moiety which can be converted subsequently into a carbonyl group. 

Ayalon-Chass, E. Ehlinger, and P. Magnus, J.C.S. Chem. Comm., 1977, 772. 

Yamamoto, and N. Sonoda, Angew. Chem. Internat. Edn., 1977,16, 789. 

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