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

by Bunel, Emilio E.

Abstract (Summary)
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. 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.
Bibliographical Information:

Advisor:John E. Bercaw

School:California Institute of Technology

School Location:USA - California

Source Type:Master's Thesis

Keywords:chemistry

ISBN:

Date of Publication:06/01/1988

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