Mini-Reviews in Organic Chemistry - Volume 2, Issue 1, 2005

This mini-review outlines recent key developments in the use of dendritic architectures in selfassembly processes via utilisation of molecular recognition motifs.

Lantibiotics are peptide-derived antimicrobial agents that are ribosomally synthesized and posttranslationally modified to their biologically active forms. The post-translational modifications involve the formation of dehydroalanine and dehydrobutyrine residues and the subsequent attack of cysteines within the peptide onto the dehydro amino acids. This generates the so-called lanthionine and methyllanthionine thioethers that have given lantibiotics their name. One family member, nisin, has attracted much attention recently due to its novel mechanism of action including specific binding to the bacterial cell wall precursor lipid II, followed by membrane permeabilization. Nisin has been commercially used as a food preservative, while other lantibiotics show promising activity against bacterial infections. This mini-review focuses on the recent developments in the characterization of these enzymes as well as the progress in chemical synthesis of lanthionine containing peptides.

Enantiomerically pure and conformationally constrained cyclic β-amino acids have been the subject of a vast amount of research across the chemical, biological, and medicinal disciplines. These valuable molecules are synthetic precursors for a wide variety of useful compounds that include natural products and modified peptides. Many methods have been developed to prepare chiral cyclic β-amino acids in high optical purity. This mini-review will discuss some of the most recent and successful approaches.

In this review some theoretical studies devoted to the mechanism of domino cycloaddition reactions are summarised. The analysis of the stationary points along the reaction pathways: transitions structures, intermediates and adducts, allows rationalising the chemoselectivity, regioselectivity and stereoselectivity experimentally observed.

Elaboration of isoxazolidines derived from the 1,3-dipolar cycloaddition of C-alkoxycarbonyl nitrones to suitably substituted alkenes leads to the development of new synthetic methodologies for the preparation of a wide range of natural products and derivatives including lactones, lactams and complex nucleosides. The insertion of a chiral centre in position β, with respect to nitrone functionality, or the presence of a chiral auxiliary at the nitrogen atom have allowed the enantioselective synthesis of the same compounds.

Suitable electrochemical methodologies for the generation of cyanomethyl anion and some electrochemically induced cyanomethylation reactions of electrophilic substrates are described and discussed. In addition, the electrochemical syntheses of carbamates and chiral oxazolidin-2-ones (under mild conditions and avoiding the use of hazardous chemicals), via a new carboxylating reagent (CH2CN- / CO2), are reported in this article.

Vinylphosphonates are an important group of compounds. This review summarizes recent developments in the synthesis and transformations of vinylphosphonates. Owing to the importance of vinylphosphonates, many different synthetic methods have been developed. Especially useful are various organometallic synthetic methods utilizing the chemistry of copper, titanium, zirconium, and lithium, etc. The transformations of vinylphosphonates is also described and include expoxidation, cycloaddition, Suzuki coupling, and Diels-Alder reactions.