A Thioxanthone Sensitizer with a Chiral Phosphoric Acid Binding Site: Properties and Applications in Visible Light‐Mediated Cycloadditions
作者:Franziska Pecho、You‐Quan Zou、Johannes Gramüller、Tadashi Mori、Stefan M. Huber、Andreas Bauer、Ruth M. Gschwind、Thorsten Bach
DOI:10.1002/chem.202000720
日期:2020.4.21
displays two thioxanthone moieties at the 3,3'-position as light-harvesting antennas. Despite its relatively low triplet energy, the phosphoric acid was found to be an efficient catalyst for the enantioselective intermolecular [2+2] photocycloaddition of β-carboxyl-substituted cyclic enones (e.r. up to 93:7). Binding of the carboxylic acid to the sensitizer is suggested by NMR studies and by DFT calculations
制备具有2,2'-联萘酚核心的手性磷酸,其在3,3'-位置显示两个噻吨酮部分作为光收集天线。尽管磷酸具有较低的三重态能量,但发现它是β-羧基取代的环状烯酮的对映选择性分子间[2 + 2]光环加成反应的有效催化剂(高达93:7)。NMR研究和DFT计算表明,羧酸与敏化剂的结合是通过两个氢键实现的。结合事件不仅使对映体分化,而且还调节了底物的三重态能量。