1. Pd2+-Catalyzed Cyclocopolymerization of 1,5-Hexadiene and CO: Regioselectivity of Olefin Insertion
- Author
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Robert M. Waymouth and Samuel L. Borkowsky
- Subjects
Reaction mechanism ,Olefin fiber ,Chloroform ,Polymers and Plastics ,Organic Chemistry ,Regioselectivity ,Cyclohexanone ,chemistry.chemical_element ,Medicinal chemistry ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Pyridine ,Materials Chemistry ,Organic chemistry ,Palladium - Abstract
The cyclocopolymerization of 1,5-hexadiene and CO with Shell-type catalyst systems comprising palladium(II) complexes in the presence of chelating phosphines yields soluble cyclocopolymers containing 5- and 6-membered cyclic ketones. Cyclocopolymerization of 1,5-hexadiene and CO in the presence of Pd(OAc)2, 1,3-bis(diphenylphosphino)propane (Dppp), 1,4-naphthaquinone, and Ni(ClO4)2·6H2O in chloroform/methanol (100−20/1) afforded a soluble cyclocopolymer 2 containing both 5- and 6-membered ring ketones in the polymer backbone. Cyclocopolymerization under similar conditions in the presence of 1,3-bis(diisopropylphosphino)propane (Dipp) gave a soluble cyclocopolymer 3 containing only 6-membered rings. Epimerization of the 6-membered ring cyclocopolymer 3 with 4-(dimethylamino)pyridine provided evidence for an initial prevailingly cis microstructure (ca. 3/1 cis/trans) for the 2,5-disubstituted cyclohexanone repeating units of the cyclocopolymer. The regioselectivity for insertion of 1,5-hexadiene into the Pd...
- Published
- 1996
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