UNPRECEDENTED MCMURRY REACTIONS WITH ACYLSILANES - ENEDISILANE FORMATION VERSUS BROOK REARRANGEMENT

The first inter- and intramolecular McMurry reactions of aroyltrimethylsilanes to substituted 1,2-bis(trimethylsilyl)ethene derivatives 2a-c and 7 are described. A low-valent titanium reagent prepared by the reduction of TiCl3 with Na on inorganic supports (Al2O3, NaCl, TiO2) turned out to be best suited. Depending on the reaction conditions and on the particular substitution patterns of the substrates, Brook rearrangements of the intermediate 1,2-disilylated titanium-1,2-diolates leading to the formation of C,O-disilyl-enol ethers may compete with the McMurry deoxygenation pathway.