Nobuyoshi Yasui

Enantioselective Single-Crystal-to-Single-Crystal Photodimerization of Coumarin and Thiocoumarin in Inclusion Complexes with Chiral Host Compounds.

An intermolecular enantioselective photoreaction by a single-crystal-to-single-crystal transformation has been carried out for the first time, as is evident from X-ray structure analysis and X-ray powder diffractometric studies. This reaction, the dimerization of the title compound to cyclobutane derivative 1 (X=O, S), provides a good example for studying the mechanism of topochemical reactions in the crystal.

Single-Crystal-to-Single-Crystal Enantioselective [2+2] Photodimerization of Coumarin, Thiocoumarin and Cyclohex-2-enone in the Inclusion Complexes with Chiral Host Compounds

Abstract Single-crystal-to-single-crystal enantioselective [2+2] photodimerization reactions of coumarin (1a), thiocoumarin (1b) and cyclohex-2-enone (2) were found to proceed efficiently in inclusion complexes with (R,R)-(−)-trans-bis(hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxacyclopentane (3a), (R,R)-(−)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[4.4]nonane (3b), and (−)-1,4-bis[3-(o-chlorophenyl)-3-hydroxy-3-phenylprop-1-ynyl]benzene (4), respectively. Through these reactions, (−)-anti-head-to-head dimer 6a, (+)-anti-head-to-head dimer 6b and (−)-syn-trans dimer 10 were obtained in 100, 100 and 48% ee, respectively.

Enantioselektive Einkristall-zu-Einkristall-Photodimerisierung von Cumarin und Thiocumarin in Einschlußkomplexen mit chiralen Wirtverbindungen

Eine intermolekulare enantioselektive Photoreaktion, die uber eine Einkristall-zu-Einkristall-Umwandlung erfolgt, wurde erstmals durchgefuhrt; Belege hierfur wurden durch Rontgenstrukturanalyse und Rontgenpulverdiffraktometrie erbracht. Diese Reaktion, die Dimerisierung der Titelverbindungen zu Cyclobutanderivaten 1 (X=O, S), liefert ein gutes Beispiel zur Untersuchung des Mechanismus von topochemischen Reaktionen im Kristall.