Double titanocene-catalyzed

Titanocene-catalyzed Double Alkylation or Double Silylation of Styrenes... 

Tab. 3.23 Titanocene-catalyzed double alkylation of olefins with alkyl bromides...

Assisted Metallations of Unsaturated Hydrocarbons. Titanocenes and zir-conocenes catalyze the addition of M—R (M = B, Mg, Al R = H, alkyl) bonds across C=C double bonds. The bydroboration of olefins (eq. 40) is believed to involve the species Cp2Ti(BH4)2 (252). 

Analogically to the titanocene(III) hydride catalyzed reactions, the zir-conocene 1 can be used as well. However, in this case the active species is assumed to be a cationic zirconium(IV) hydride generated by the reaction of the zirconocene 1 with MAO. The reaction mechanism copies the one described in Scheme 40. However, the course of the reaction favors antz-Markovnikov addition of the zirconium hydride to the double bond to give solely the methyl-enecycloalkanes 93 [50,51]. 

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