Printed in Gteat Britain oMo4039190 $3.00 +.a0 Pergamcm Rez?s plc A FINE-TUNING OF PHOTOREACTIVITY OF LARGE RING 2-PHENYLCYCLOALKANONES ADSORBED IN CYCLODEXTRINS

Abstract The photochemistry of solid complexes of large ring 2-phenylcycloalkanones adsorbed in cyclodextrin cavities results in significant yields of enals as disproportionation products, at the expense of the para-rearrangement, depending on both the ring size of the cyclanone and the cavity size of the cyclodextrin. This behavior contrasts with its photoreaction in homogeneous solutions which yields predominantly para-cyclophanes. Introduction The quest for chemical catalysis and selectivity through host-guest complexation has received considerable recent attention.1 For example, inclusion complexes of cyclodextrins have been successfully utilized in catalysis and selectivities in numerous thermal reactions. 2 Cyclodextrins are commonly available in three distinct forms, termed a, p and y, which possess internal cavity diameters of 4.9 A, 6.2 A and 7.9 A, respectively. Depending on the size, the shape and the hydrophobicity of the guest organic molecules, the hydrophobic cavities o