Enantioselective cyclopolymerization of 1,5-hexadiene catalyzed by chiral zirconocenes: A novel strategy for the synthesis of optically active polymers with chirality in the main chain

Journal Article · Wed Jan 13 00:00:00 EST 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00054a014· OSTI ID:6784292

Coates, G W; Waymouth, R M ^[1]

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1. Stanford Univ., CA (United States)

Enantioselective cyclopolymerization represents a novel strategy for the synthesis of optically active main-chain chiral polymers. Cyclopolymerization of 1,5-hexadiene using the optically active catalyst precursor, (R,R)-(EBTHI)ZrBINOL ((R,R)-1) [EBTHI = ethylene-1,2-bis([eta][sup 5]-4,5,6,7-tetrahydro-1-indenyl); BINOL = 1,1[prime]-bi-2-naphtholate], yields optically active poly(methylene-1,3-cyclopentane) (PMCP) with a molar optical rotation of [[Phi]][sup 28][sub 405] +51.0[degrees] (c = 0.80, CHCl[sub 3]). The molar optical rotation for the polymer derived from (R,R)-1 is higher than that of the model compound trans-(1R,3R)-1,3-dimethylcyclopentane and is also temperature dependent, suggesting that the polymer adopts chiral conformations which contribute to the observed optical rotation. The microstructure of the polymer was interpreted by [sup 13]C NMR at tetrad resolution. A statistical model for the microstructure based on an enantiomorphic site control mechanism provided good agreement with the experimental data. On the basis of this model, the enantioface selectivity for the cyclopolymerization of 1,5-hexadiene in the presence of catalysts derived from (R,R)-1 is 91% at 20[degrees]C, indicative of a highly isotactic microstructure. The molar optical rotation of poly(methylene-1,3-cyclopentane) is independent of molecular weight, which provides experimental support for an enantiomorphic site control mechanism. The absolute configuration of PMCP was tentatively assigned on the basis of the sign of the optical rotation of the model compound trans-(1R,3R)-1,3-dimethylcyclopentane and the known enantioface selectivity of 1 with similar [alpha]-olefins. 46 refs., 12 figs., 5 tabs.

• OSTI ID: 6784292
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 115:1; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ORGANIC POLYMERS
CHEMICAL PREPARATION
ORGANOMETALLIC COMPOUNDS
CATALYTIC EFFECTS
ZIRCONIUM COMPOUNDS
ALKENES
CATALYSTS
CHEMICAL REACTION YIELD
CHIRALITY
MATHEMATICAL MODELS
MICROSTRUCTURE
NUCLEAR MAGNETIC RESONANCE
POLYMERIZATION
POLYMERS
PRECURSOR
SYNTHESIS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
HYDROCARBONS
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
PARTICLE PROPERTIES
RESONANCE
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
YIELDS
400201* - Chemical & Physicochemical Properties