Current Organic Chemistry - Volume 12, Issue 13, 2008

This article reviews the isolation, biological activity and syntheses of several diterpenes. The chemistry and biological activities of norditerpene dilactones have been described. The aim of the present article is to provide an overview on the important role of diterpenoid compounds in medicine and agriculture. The synthetic discussions of these diterpenes are very briefly described.

The last decade has witnessed an increasing interest in sugar urea derivatives because of their biological properties. Consequently, new synthetic procedures that explore reactivity differences of the sugar units for the synthesis of molecules bearing urea moiety linked to sugars architecture, have been investigated. The main routes involve isocyanate species, also obtained from the oxidation of isocyanides, by direct reaction with amines or aminosugars or more recently by aza-Wittig reaction with sugar-derived phosphinimines. Other important strategies are based on the reaction of sugarderived oxazolidinones and carbamates with amines, and modified Curtius rearrangement of sugar carboxylic acids or reaction of sugar-derived phosphinimines with carbon dioxide and amines. This review provides a comprehensive survey of synthetic approach to carbohydrate-based ureas with a focus on the recent procedures.

Reductive amination is one of the most useful and versatile methods for the preparation of amines in chemistry and biology. The present review focuses on the development of catalytic reductive amination from beginning to recent ones, where we have attempted to thoroughly illustrate an account of utility of various reagents including organocatalyst, symmetric and asymmetric (Ru, Rh, Ir) complexes, boron, tin or silicon reagents etc for enantio- and/or chemoselective reactions under different reaction conditions with emphasis on the yields of the reaction products and stability of the reagents used. Emerging applications of this reaction for the development of chiral ligands, pharmacologically active molecules, combinatorial scaffold, and key step in the total synthesis of some interesting natural products is also reviewed briefly.

Quinoline is a heterocyclic scaffold of paramount importance to human race. The utility of quinoline derivatives in the areas of medicine, food, catalyst, dye, materials, refineries and electronics is well established. As a result, the synthesis of quinoline core and its derivatives have been an attractive goal for the synthetic organic chemist. In the recent past there have been several new developments in the chemistry associated with quinolines. In pursuit to develop easy and practical approaches to a variety of quinoline derivatives decorated with useful pharmacophores different research workers have made use of new catalysts, medium or physical conditions in several well established synthetic methodologies. Besides an array of new and innovative strategies from novel substrates have been developed which has rendered the synthesis of quinoline core a much simpler process as compared earlier. An assimilation of the literature related to the advances in the syntheses of quinolines and quinoline-annulated ring systems since 2005 is being presented here.