Current Organic Chemistry - Volume 12, Issue 7, 2008

The 2008 Catalysis/Natural Product Chemistry issue of Current Organic Chemistry contains two contributions from eminent scientists in different field. Professor Sartori and coworkers review the use of organic solid supported base as cataliyst in organic synthesis in the last decade. The synthesis of α-amino ketones are of great importance in organic synthesis. Professor Cancellon and her group provide an overview of the literature reported methods for the synthesis and synthetic application of this type of compounds. I would like to express my sincere thanks to all the authors for providing these articles and for the fascinating results described.

Enantiomerically pure α-amino ketones are of great importance in natural product synthesis and pharmacological research. However no review concerning their synthesis and applications has been published. Therefore, this review is intended to highlight the above compounds, detailing the available methodologies to prepare enantiopure α-amino ketones in the first part and some synthetic application in the second.

Organic bases represent a class of widely utilized catalysts in organic synthesis. During the last decade many research groups have been involved in the challenge of supporting homogeneous catalysts on the surface of organic and inorganic supports with the aim of producing efficient heterogeneous and reusable catalysts. Among these catalysts organic bases (i.e. amines, guanidines, etc.) have received particular attention. The present review shows the developments made during the last twenty years in the area of preparing, characterizing and applying supported organic bases for the synthesis of fine chemicals. The methods for the preparation of the supported catalysts are briefly discussed. Particular attention is paid to find possible correlations between the methodologies utilized to prepare the solid catalysts and their efficiency in model reactions of general interest; in addition the identification of possible leaching phenomena and the approaches to face the problem of preventing the catalyst deactivation are considered. The complexity of the supported base catalysts, the difficulty frequently encountered by reactants in reaching the active sites and the role played by the unfunctionalized surface of the support are also discussed together with the description of the efficient recovery and reusability of these hybrid catalysts. Finally, after some general conclusions, future trends are presented.

Alkalides are salts containing alkali metal anions and complexed metal cations. These unusual species discovered by Dye (Dye, J.L.; Andrews, C.W.; Mathews, S.E. J. Phys. Chem., 1975, 79, 3065) are strong reductants of many organic and inorganic compounds. These reactions occur rapidly under mild homogeneous conditions. In this paper we discuss new data concerning the application of potassium potassides selected from the group of alkalides to polymerization processes. Their new and corrected mechanisms for some vinyl and oxacyclic monomers are presented.

Lipopolysaccharides (LPSs) constitute the lipid portion of the outer leaflet of Gram-negative bacteria; they are essential for growth, and are also responsible for the variety of biological effects associated with Gram-negative sepsis. Recent advances have elucidated the exact chemical structure of this highly complex macromolecule and part of the enzymology involved in its biosynthesis. Enzymes involved in LPS biogenesis are optimal targets for the development of novel therapeutics since they are sufficiently conserved among diverse, clinically-relevant bacteria and no analogue counterpart is present in humans. During the last thirty years a number of inhibitors to LPS biosynthesis have been developed: some of these compounds have antibacterial properties, while others show excellent in vitro activity and are undergoing further investigation. This review will focus on the biology of LPS in bacteria summarizing the knowledge about structure and enzymatic catalysis, as well as chemical efforts towards the synthesis of inhibitors of the key enzymes involved in the biosynthesis of the minimal conserved structure Kdo2-LipA, also referred to as Re LPS. Only a short overview will be given on lipid A biosynthesis and inhibitors, while main focus will be Kdo biosynthesis towards Re LPS. Future directions and perspectives will also be outlined.