Cope rearrangement kinetic isotope effects

Another series of publications from Ken s group compared kinetic isotope effects, computed for different possible transition structures for a variety of reactions, with the experimental values, either obtained from the literature or measured by Singleton s group at Texas A M. These comparisons established the most important features of the transition states for several classic organic reactions — Diels-Alder cycloadditions, Cope and Claisen rearrangements, peracid epoxidations, carbene and triazolinedione cycloadditions and, most recently, osmium tetroxide bis-hydroxylations. Due to Ken s research, the three-dimensional structures of many transition states have become nearly as well-understood as the structures of stable molecules. 

Gajewski, J. J. Conrad, N. D. Variable transition-state structure in the Cope rearrangement as deduced from secondary deuterium kinetic isotope effects, J. Am. Chem. Soc. 1978,100, 6269-6270. 

Houk, K. N., Gustafson, S. M., Black, K. A. Theoretical secondary kinetic isotope effects and the interpretation of transition state geometries. 1. The Cope rearrangement. J. Am. Chem. Soc. 1992,114, 8565 572. 

Ozkan, I., Zora, M. Transition Structures, Energetics, and Secondary Kinetic Isotope Effects for Cope Rearrangements of cis-1,2-Divinylcyclobutane and cis-1,2-Divinylcyclopropane A DFT Study. J. Org. Chem. 2003, 68, 9635-9642. 

Even when the cyanide group is not directly involved in the reaction, it can have a considerable influence on the reaction mechanism. A study of kinetic deuterium isotope effects on a series of Cope rearrangementsshowed that rearrangement of the 3,3-dicyanohexa-1,5-diene (132) had the /rn/te ratio at C(4) (i.e. bond breaking) greater than the A d/ h ratio at C(6) bond making) rather than the reverse, which was observed with other substituents. A theoretical studyof the reaction indicated that this reaction is... 

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