Synthetic and mechanistic studies of organoscandium compounds. Dimerization and branching of alkenes catalyzed by scandocene hydrides

Citation

Bunel, Emilio E. (1989) Synthetic and mechanistic studies of organoscandium compounds. Dimerization and branching of alkenes catalyzed by scandocene hydrides. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-05242007-075254

Abstract

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Mixed-ring scandocene alkyl and hydride derivatives of structure [...], [...], [...], and [...] were prepared [...]. Dimethylsilicon bridged scandocene alkyl and hydride derivatives [...], [...], [...], and [...] were also prepared. The activation energy for phosphine dissociation in [...] and [...] were measured. The crystal structures of [...] and [...] were determined.

The hydride derivatives, [...] and [...] catalyze the following carbon-carbon bond forming reactions: (1) The catalytic dimerization of [alpha]-olefins to head-to-tail dimers, (2) The catalytic cyclization of [alpha,omega]-diolefins to methylenecycloalkanes with ring sizes between 5 and 9 carbon atoms, (3) The catalytic formation of six-membered ring nitrogen and sulfur heterocycles by catalytic cyclization of bisallyl amines and bisallyl sulfides respectively and (4) The catalytic formation of the spiro hydrocarbons 2-methylene spiro[4.4] nonane and 2-methylene dispiro [4.1.4.2] tridecane by catalytic cyclization of 5-methylene-1,8-nonadiene and 5,8-dimethylene-1,11-dodecadiene.

[...] catalyzes the ring opening reaction of methylenecyclopropane to butadiene and methylenecyclobutane to 1,4-pentadiene. Labeling experiments show that intramolecular olefin insertion in [omega]-alkenyl scandium complexes and [beta]-alkyl elimination in cycloalkylmethyl scandium complexes is reversible when rings containing 3 or 4 carbon atoms are involved. The hydride derivative [...] also catalyzes the isomerization of 1,4-pentadiene to isoprene and 2-methyl-l,4-pentadiene to 2,3-dimethylbutadiene and the isomerization of 3-methyl-l,4-pentadiene to 1,5-hexadiene, which is then cyclized to methylenecyclopentane.

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