Scandocene hydride

A cyclobutylmethyl-metal system provides another opportunity to observe 13-carbon elimination. The ring opening process harnesses the release of the least necessitating ring strain of a four-membered ring. Scandocene hydride 63 reacts with 3-methyl-l,4-pentadiene to afford the linear Ji-allyl complex 65 [80]. The intermediacy of cyclobutylmethyl complex 64 which undergoes P-carbon elimination accommodates the observed rearrangement. 

In the presence of scandocene hydride 63,3-methyl-l,4-pentadiene is catalyt-ically converted to methylenecyclopentane and its isomer via cyclobutylmethyl-metal intermediate 64 [80]. 

On the other hand, scandocene hydride 10 prompted isomerization of penta-1,4-diene to isoprene (2-methylbutadiene) via a cyclopropylmethylmetal intermediate (Scheme 7.4) [5]. 

Bercaw reported an interesting reversible branching reaction of 1,4-penta-diene derivatives catalyzed by a scandocene hydride complex as shown in Scheme 6 [24]. 

In addition to zirconocenes, C -symmetric scandocenes and yttrocenes with two dimethylsilyl interannular linkers (38a-c, 39, Figure 4.18) have been synthesized and tested as polymerization catalysts for propylene and 1-pentene." " Owing to the electronics of these group 3 catalysts (14-electron, d electronic configuration) no cocatalysts are required. However, metallocene chlorides cannot be used for polymerization metallocene alkyl or hydride compounds are necessary. 

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