Stepwise Approach toward First Generation Nonenzymatic Hydrolases

Molecular protection of fatty acid methyl esters within a supramolecular capsule

We describe the use of a supramolecular nano-capsule for selective protection of cis- and trans-C18 mono-unsaturated fatty-acid esters.

Bis-Michael Acceptors as Novel Probes to Study the Keap1/Nrf2/ARE Pathway

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulator that promotes the transcription of cytoprotective genes in response to oxidative/electrophilic stress. Various Michael-type compounds were designed and synthesized, and their potency to activate the Keap1/Nrf2/ARE pathway was evaluated. Compounds bearing two Michael-type acceptors proved to be the most active. Tether length and rigidity between the acceptors was crucial. This study will help to understand how this feature disrupts the interaction between Keap1 and Nrf2.

Synthesis of functionalised nucleosides for incorporation into nucleic acid-based serine protease mimics

The synthesis of nucleosides modified with an extra imidazole, carboxyl and hydroxyl group is described. These nucleosides can be incorporated into an oligonucleotide duplex, thus generating a novel type of serine protease mimic.

Kinetic Resolution of Protected α-Amino Acid Derivatives by a Chiral O-Nucleophilic Acyl Transfer Catalyst

The kinetic resolution of alpha-trifluoroacetamido N-acyl oxazolidinethiones using 5-10% of the chiral, nonracemic O-nucleophilic acyl transfer catalyst 2 is described. A variety of substrates participate in this reaction in excellent yields, with s-factors ranging from 20 to 86.

Kinetic Resolution of α-Acetoxy N-Acyl Oxazolidinethiones by a Chiral O-Nucleophilic Acyl Transfer Catalyst

The kinetic resolution of alpha-acetoxy N-acyl oxazolidinethiones using the chiral, nonracemic O-nucleophilic acyl transfer catalyst 8 is described. The reaction proceeds on a variety of substrates in excellent yields, with s-factors ranging from 17 to 31.

Enhanced selectivities for the hydroxyl-directed methanolysis of esters using the 2-acyl-4-aminopyridine class of acyl transfer catalysts: ketones as binding sites

In this paper we describe the preparation of a series of 2-acyl-4-aminopyridines, and their use as catalysts for the hydroxyl-directed methanolysis of alpha-hydroxy esters in preference to alpha-methoxy esters. Hydroxyl-direction with these catalysts, which contain ketones at the 2-position of the pyridine, is achieved by reversible addition of the alcohol of the hydroxy ester to the ketone to provide the corresponding hemiketal. Their activity is compared to that of the previously described catalyst 2-formyl-4-pyrrolidinopyridine (FPP), which contains an aldehyde at the 2-position of the pyridine. The catalysts which contain ketones at the 2-position range in reactivity from 10 times slower to slightly faster than FPP, and certain of these are much more selective for the methanolysis of hydroxy esters than FPP. This increase in selectivity is ascribed to a decrease in the rate of the nondirected methanolysis reaction with the ketone-derived catalysts. The evidence suggests that the nondirected reaction does not proceed by an intermolecular general base mechanism, but rather via a nucleophilic catalysis mechanism in which the hydroxyl group of the hemiacetal formed upon addition of methanol to the aldehyde of FPP acts as the nucleophile. Since the hydroxyl group derived from a hemiketal is more hindered and less nucleophilic than that derived from a hemiacetal, the nondirected reaction is much slower for the catalysts containing ketones as binding sites.