Photo-fries reaction of naphthyl esters within zeolites

Copper catalyzed oxidative deamination of Betti bases: an efficient approach for benzoylation/formylation of naphthols and phenols

A copper-catalyzed benzoylation/formylation of naphthols and phenols via oxidative deamination of Betti bases.

Photo-Fries reaction in water made selective with a capsule

The water soluble capsule formed by a deep cavity cavitand with eight carboxylic acid groups controls product distribution during photo-Fries rearrangement of naphthyl esters in water by restricting the mobility of primary singlet radical pair.

Photoproduct selectivity in reactions involving singlet and triplet excited states within bile salt micelles

Generally, photochemical reactions tend to give more than one product. For such reactions to be useful one should be able to control them to yield a single product. Of the many approaches used in this context, the use of reaction media with features different from those of isotropic solutions has been very effective. We provide results of our studies on four reactions within bile salt micelles (cholic acid and deoxycholic acid). These four reactions involve homolytic cleavage of a C-C or C-O bond to yield either a singlet or triplet radical pair. The bile salt micelles control the rotational and translational mobilities of the radical pair, resulting in photoproduct selectivity. The dynamic nature of the bile salt micelles results in differential effects on the singlet and triplet radical pairs.

Amphiphilic Homopolymer as a Reaction Medium in Water: Product Selectivity within Polymeric Nanopockets

A styrene-based water-soluble polymer has been explored for its use as a host for lipophilic substrates in aqueous medium. Unimolecular reactions, namely, photo-Fries rearrangement of naphthyl esters, alpha-cleavage reaction of 1-phenyl-3-p-tolyl-propan-2-one, and Norrish type I and type II reactions of benzoin alkyl ethers were examined. We find that the hydrophobic domains generated by the polymer not only restrict the mobility of the radicals but also modestly incarcerate the substrate, intermediates, and products during the time scale of the reactions. Comparative studies of the same photoreactions in micelles formed from small molecule surfactants and an amphiphilic diblock copolymer demonstrate that the styrene-based water-soluble polymer aggregates in aqueous medium offer better selectivity.

An EPR investigation of persistent radicals from the photolysis of p, p'-dialkyl-substituted phenyl benzyl ketones adsorbed on MFI zeolites

The photolysis of isomeric pairs of p,p'-dialkyl-substituted phenyl benzyl ketones adsorbed on MFI zeolites has been investigated by EPR spectroscopy. Photolysis produces persistent "benzoyl type" and "benzyl type" radicals. The dominant persistent radical produced by photolysis of any particular isomeric pair depends on the length and position of the p-alkyl chain. The results are attributed to supramolecular stereoisomers resulting from preferential adsorption of the longer alkyl chain into the pores of the zeolite.