Selectivity in the photo‐Fenton and photocatalytic hydroxylation of biphenyl‐4‐carboxylic acid and derivatives (viz. 4‐phenylsalicylic acid and 5‐phenylsalicylic acid)

Abstract

The selectivity of hydroxylation of the distal rings of 4‐phenylbenzoic acid, 4‐phenylsalicylic acid, and 5‐phenylsalicylic acid were determined using partial TiO2‐mediated photocatalytic degradation and photo‐Fenton conditions. This separation of the binding site from the phenyl group being hydroxylated allows a less‐biased evaluation. The hydroxylation regiochemistry behaves as qualitatively expected for an electrophilic reaction, given the assumption that 4‐carboxyphenyl is a slightly electron‐withdrawing substituent. Selectivity for hydroxylation of the distal phenyl in 4‐ and 5‐phenylsalicylic acid is reversed, due to the reversal of the electronic demand, while adsorption to the TiO2 surface is assumed to be analogous for the two structures. Copyright © 2011 John Wiley & Sons, Ltd.

Salicylic Acid Derivatives Inhibit Oxalate Production in Mouse Hepatocytes with Primary Hyperoxaluria Type 1

“…C3′-Thienyl derivatives did not improve the potency of their C2′ counterparts (37 and 38) (Table 3). Exploration of different substitution on the C2′-bound thiophene ring, such as acetyl (41) or methyl (42) groups, led to poor mGOi's without activity on cells (Table 3). Nitrogen heterocycles pyrazol (43) and pyrimidine (44) produced no improvement in the mGO inhibitory activity or the oxalate decrease capacity.…”

“…Compound 11 bears a p-nitrophenoxy side chain. We prepared the corresponding arylsalicylate with the same electronwithdrawing p-nitro (45) and also derivatives with electrondonating m-methoxy (46) and p-hydroxy (47) 42 groups on ring B (Figure 12). The three compounds contain hydrogen acceptor substituents, but only the hydroxyl group on 47 could act as a hydrogen donor.…”