Titanium cyclopentadienide complex

A useful alternative to phosphorus ylids are the titanium reagents, such as, 71, prepared from dicyclopentadienyltitanium dichloride and trimethylaluminum. Treatment of a carbonyl compound with the titanium cyclopentadienide complex 71 Tebbe s reagent) in toluene-THF containing a small amount of pyridine " leads to the alkene. Dimethyltitanocene (Me2TiCp2), called the Petasis reagent, is a convenient and highly useful alternative to The mechanism of Petasis... 

Ring-substituted derivatives of nickelocene, cobaltocene, and of molybdenum and titanium 71-cyclopentadienyls, which would be difficult to make by direct substitution of the parent metal-ring complex, have been made starting with these substituted cyclopentadienides [17, 18]. 

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