β-Cyclodextrin effects on photo-Claisen rearrangement of allyl phenyl ether

Abstract

The photo rearrangement of allyl phenyl ether (1) in water and in solutions containing β-cyclodextrin (β-CD) leads to the para (2) and ortho (3) allyl phenols and phenol (4) as principal products. The substrate associates with β-CD forming a 1:CD complex with a K1-CD = (4.6 ± 0.6) × 102 M−1. When the photolysis is carried out in presence of oxygen there is a decrease in the total yields of products, but the inhibition is less marked in the presence of β-CD. The product quantum yields (Φ) for the complexed substrate are different for the free substrate, being higher for the ortho product, almost the same for the para product, and lower for phenol. The ortho selectivity was confirmed in the photolysis of the solid complex; these results are in agreement with those reported by this laboratory for the photo-Fries rearrangement of acetanilide and phenyl acetate. Keywords: cyclodextrin, photo-Claisen rearrangement, selectivity.