PHOTODIMERIZATION REACTION OF COUMARIN IN COMPLEX CRYSTALS WITH CHIRAL HOST DERIVED FROM TARTARIC ACID. Ikuko Miyahara*, Yoshitaka Nakajima*, Ken Hirotsu*, Koichi Tanaka**, and Fumio Toda** Faculty of Science, Osaka City University*, Faculty of Engineering, Ehime University**

The chiral hosts molecules derived from tartaric acid have been reported to make the inclusion complexes with various kinds of guest molecules and used as chiral handles to control the stereospecificity of the reaction on the basis of the asymmetryic environment around the guest molecules in solid state. Photodimerization of coumarin (2H-1benzopyran-2-one) in solution does not proceed stereospecifically. On the other hand, the inclusion crystals between the chiral hosts (-)- bis (hydroxydiphenyLmethyl)-2,2-dimethyl-1,3-dioxacyclopentane (1) and coumarin were irradiated to give the products in a stereocontrolled manner. In order to elucidate the relationship between the reactivity, arrangements of guest molecules, and intermolecular interactions, X-ray studies of these complex crystals were undertaken.

The complex of (-)-(1) and coumarin crystallized as monoclinic (C2) and triclinic (P1) forms from ethylacetate and toluene, respectively. On the irradiation of these crystals, the chiral dimer was obtained from the monoclinic form and the achiral dimer from the triclinic forms. The racemic complex crystal (P1) between (+)-(1) and coumarin was also irradiated, but no photoproduct was detected. The mechanism of reactivity and stereochemical control will be presented.