A novel enzymatic, promiscuous protocol for Candida antarctica lipase B (CAL-B)-catalyzed carbon-sulfur bond addition is described. Some control experiments have been designed to demonstrate the catalytic specificity of CAL-B. Selectivity between anti-Markovnikov addition and Markovnikov addition was achieved in different organic media. A series of thioether-containing ester functional groups was synthesized under the catalysis of CAL-B at 50 8C. All the products were characterized by spectroscopic methods (IR, NMR, ESI-MS).

No abstract

A mathematical expression describing the growth regime of multilayers formed layer by layer and the correlation between the nature of the growth process and the distribution of the charges in the polyelectrolyte deposited on the surface of the film is reported. Two typical polyelectrolyte pairs were chosen such that one of them causes the film to grow linearly while the other causes the film to grow exponentially. The growth processes were monitored by UV‐Vis spectrophotometry and the experimental data was analyzed. The influence of the polyelectrolyte and NaCl concentration on the fabrication of PAH/PSS and PDDA/PSS films is discussed by analyzing the change of model parameters.

Three acylases, including d-aminoacylase from Escherichia coli, acylase "Amano" from Aspergillus oryzae and immobilized penicillin G acylase from Escherichia coli have been found to possess novel activity to catalyze the Markovnikov addition reaction of N-heterocycles to vinyl esters. The aza-Markovnikov addition reactions of 4-nitroimidazle to vinyl acetate catalyzed by d-aminoacylase, acylase "Amano" and immobilized penicillin G acylase were up to 1260-fold, 720-fold and 320-fold faster than the respective non-enzymatic reaction. Some control experiments have been designed to demonstrate the catalytic specificity of acylases. Under the catalysis of these promiscuous acylases, a number of N-heterocycles, including some pentacyclic N-heterocycles, pyrimidines and purines, were successfully added to a series of vinyl esters in moderate to excellent yields to prepare N-heterocycle derivatives. The acylase-catalyzed Markovnikov addition reaction has provided a new strategy to perform the Markovnikov addition and expanded the application of biocatalysts.

No abstract