60245-62-7Relevant articles and documents
Theoretical and Experimental Studies of Regioselectivity in Selenoxide Elimination
Kondo, Noboru,Fueno, Hiroyuki,Fujimoto, Hiroshi,Makino, Mineyuki,Nakaoka, Hiroaki,et al.
, p. 5254 - 5263 (2007/10/02)
In order to gain insight into the mechanism of selenoxide elimination, the transition state structures have been determined by applying the ab initio MO method to the elimination for systems having a simplified skeleton, CH2(Y)CH(Se(O)CH3)CH3 (Y = OCH3, OH, CN and Cl).The calculations show that an allylic alkyl ether and an allylic alcohol ahould be produced preferentially in the case of Y = OCH3 and OH, respectively, whereas a vinylic cyanide should be the major product in the case of Y = CN.The chloro-substituted model has given a result most consistent with the methoxy-substituted model.The elimination occurs via a transition state with a five-membered ring structure, and the breaking of the Cβ-H bond takes place earlier than that of the Se-Cα bond, in the favorable path.The asynchronous nature of bond breaking is quite conspicuous in the cyano-substituted model, relative to the other systems.For comparison with the theoretical results, β-methoxy-, β-hydroxy-, β-cyano-, and β-chloro-substituted selenides were newly synthesized from trans-7-tetradecene, respectively, and were oxidized by H2O2 in tetrahydrofuran or in carbon tetrachloride.The regioselectivity observed for the elimination, i.e., the formation of a vinylic compound from the β-cyano selenide and a mixture of allylic and vinylic products from the β-chloroselenide, agrees well with the theoretical calculations.The difference in the activation energies of the two paths calculated for the model species is not large enough in the methoxy- and hydroxy-substituted selenides to explain the almost complete formation of an allylic compound in the physical experiments.
