Diastereoselective [2+2] Photocycloaddition of Cyclohexenone Derivative with Olefins in Supercritical Carbon Dioxide

作者：Nishiyama Yasuhiro^*; Nakatani Kazuya; Tanimoto Hiroki; Morimoto Tsumoru; Kakiuchi Kiyomi

来源：Journal of Organic Chemistry, 2013, 78(14): 7186-7193.

DOI：10.1021/jo401126p

We performed diastereoselective [2 + 2] photo-cycloaddition of the cyclohexenone derivative with olefins in supercritical carbon dioxide (scCO(2)). A dramatic enhancement of conversion was observed at around critical density when ethylene gas was employed as a coupling partner. Furthermore, we elucidated that the pressure dependence of the diastereomeric excess (de) was discontinuous at critical density owing to the difference of substrate solubility between near-critical carbon dioxide (ncCO(2)) and scCO(2); both the reaction conversion and de values obtained were lower than those in conventional organic solvent. On the contrary, when cyclopentene (liquid) was utilized as a coupling partner, moderate conversion was always observed irrespective of CO2 pressure, because the substrate could be dissolved in cyclopentene. Furthermore, we could accomplish de enhancement in scCO(2), in particular around critical density, compared to that in organic solvent. This highly selective photoreaction is due to the unique solvent property of scCO(2), which is called the clustering effect.

• 出版日期2013-7-19