9-Iodoso-10-phenanthroic acid (IPA-OH) was prepared from 9-cyanophenanthrene in a four-step, 44% overall yield synthesis, featuring cyano-directed ortho lithiation/iodination as the key step. An X-ray crystal structure showed that IPA-OH exists in a phenanthroiodoxol-3(lH)-one valence tautomeric form, 14-OH, characterized by T-shaped geometry at iodine, strong H/O steric interactions between the peri-H atoms and the carbonyl and iodoso oxygen atoms, a “short” endocyclic 1-0 bond, well-differentiated carbonyl and endocyclic C-0 bond lengths, and nonplanarity in both the iodoxolone and phenanthrene rings (Figures 1 and 2). IPA-OH was an excellent catalyst for the cleavage of p-nitrophenyl diphenyl phosphate (PNPDPP) in aqueous micellar cetyltrimethylammonium chloride (CTAC1) solutions at pH 8 and 25 °C: 1 × 10-5 M PNPDPP was cleaved by 1 × l0-4 M IPA-OH in 3.5 × 10-4 M CTAC1 with kψ = 0.38 s--1. Experiments in which [PNPDPP] > [IPA-OH] demonstrated that the catalyst “turned over”; hydrolysis of the putative phosphorylated IPA-OH intermediate was rapid.
All Science Journal Classification (ASJC) codes
- Organic Chemistry