title: Influence of hydrogen bonding in the activation of nucleophiles: PhSH-(catalytic) KF in N-methyl-2-pyrrolidone as an efficient protocol for selective cleavage of alkyl/aryl esters and aryl alkyl ethers under nonhydrolytic and neutral conditions.
abstract: The nucleophilicity of arenethiols can be augmented via hydrogen bonding with "naked" halide anion. The activity of the halide anions follow the order F(-) >> Cl(-) approximately Br(-) approximately I(-) and is dependent on the countercation (Bu(4)N approximately Cs approximately K > Na >> Li). The solvent plays an important role in nucleophilic activation as well as regeneration of the effective nucleophile (e.g. ArS(-)) and those with high dielectric constant, high molecular polarizability, high donor number (DN), and low acceptor number (AN) are the most effective. Selective deprotection of alkyl/aryl esters and aryl alkyl ethers can be achieved under nonhydrolytic and neutral conditions by the treatment with thiophenol in 1-methyl-2-pyrrolidone (NMP) in the presence of a catalytic amount of KF. Aryl esters are selectively deprotected in the presence of alkyl esters and alkyl methyl ethers during intramolecular competitions.
authors.affiliation: Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar 160 062, India. achakraborti@niper.ac.in
authors.forename: Asit K
authors.initials: AK
authors.lastname: Chakraborti
authors.forename: Lalima
authors.initials: L
authors.lastname: Sharma
authors.forename: Mrinal K
authors.initials: MK
authors.lastname: Nayak