Department of Chemistry and Catalysis Research Center (CRC), Technical University Munich, Lichtenbergstr. 4, 85747, Garching, Germany.
Faculty of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93040, Regensburg, Germany.
Chemistry. 2020 Apr 21;26(23):5190-5194. doi: 10.1002/chem.202000720. Epub 2020 Apr 15.
A chiral phosphoric acid with a 2,2'-binaphthol core was prepared that 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 to occur by means of two hydrogen bonds. The binding event not only enables an enantioface differentiation but also modulates the triplet energy of the substrates.
制备了一种具有 2,2'-联萘酚核的手性磷酸，其在 3,3'-位显示出两个硫杂蒽酮作为光收集天线。尽管其三重态能量相对较低，但发现该磷酸是β-羧基取代环状烯酮的对映选择性分子间[2+2]光环加成的有效催化剂（对映体过量高达 93:7）。NMR 研究和 DFT 计算表明，通过两个氢键发生羧酸与敏化剂的结合。结合事件不仅能够进行对映面区分，而且还调节了底物的三重态能量。
