α,β-Unsaturated selenoaldehydes and selenoketones the reaction behavior as a heterodiene and/or a dienophile
作者:Guang Ming Li、Masahito Segi、Tadashi Nakajima
DOI:10.1016/s0040-4039(00)92677-7
日期:1992.6
β-Unsaturated selenoaldehydes and selenoketones, generated in situ by selenation of the corresponding carbonyl compounds with bis[dimethylaluminum) selenide, underwent regioselective self-condensation to yield cyclic diselenide derivatives. On the other hand, in the presence of a trapping agent, they underwent intermolecular Diels-Alder cycloadditions in two different modes depending on the trapping agent
[4 + 2] Dimerization and Cycloaddition Reactions of α,β-Unsaturated Selenoaldehydes and Selenoketones
作者:Guang Ming Li、Shuqiang Niu、Masahito Segi、Ralph A. Zingaro、Hiroaki Yamamoto、Kentaro Watanabe、Tadashi Nakajima、Michael B. Hall
DOI:10.1021/jo982028n
日期:1999.3.1
undergo regioselective [4 + 2] dimerization via a "head-to-head" oriented transition state to afford diselenin derivatives (trans and cis isomers). Theoretical calculations at the density functional theory level show that this selectivity occurs because the "head-to-head" dimerization is thermodynamically favored over the "head-to-tail" by about 14 kcal/mol. Both dimerization reactions have low energy barriers: