Collect. Czech. Chem. Commun.
1996, 61, 774-777
https://doi.org/10.1135/cccc19960774
Catalyst Effects on the Stereoselectivity of Addition of Tetrachloromethane to 1,3-Cyclohexadiene
Milan Hájeka, Martin Kotoraa, František Adámeka, Reg Davisb, Cecile Fischerb and Warren A. C. Joshub
a Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6-Suchdol, Czech Republic
b School of Applied Chemistry, Penrhyn Road, Kingston upon Thames, Surrey, KT1 2EE, Great Britain
Abstract
The stereoselectivity of addition reaction of tetrachloromethane with conjugate cyclodienes represented by 1,3-cyclohexadiene has been studied in respect to the type of catalyst. In all addition reactions the product of 1,4-addition, i.e. 1-chloro-4-(trichloromethyl)cyclohex-2-ene was formed exclusively consisting of two isomers (1a, 1d). Copper-amine complexes gave higher isomeric ratio 1a : 1d (up to 3.7) than ruthenium complex (1.3) at the same conditions (80 °C). Moreover, it was found that isomeric ratio was temperature dependent and the highest value (6.4) was obtained at lower temperature (20 °C). The results proved both catalyst and ligand effects on stereoselectivity of addition reaction of conjugated cyclic dienes. This supports a non-chain reaction mechanism because isomeric ratios of chain reactions are catalyst independent.
Keywords: Addition; Stereoselectivity; Ligand effects.
