Current Organic Chemistry - Volume 15, Issue 24, 2011

During the past decade, asymmetric organocatalysis, in which small chiral organic molecules act as catalytically active species, has grown explosively to become one of the most exciting research areas in current organic chemistry. A variety of chiral organocatalysts and numerous of asymmetric organocatalytic transformations have been developed. This special thematic issue of Current Organic Chemistry aims to highlight the substantial progress on asymmetric organocatalysis and synthesis. The asymmetric Friedel Crafts reaction is one of the most powerful methods to synthesize optically active aromatic compounds. The first review, written by Xiao et al., The Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, summarizes recent advances on organocatalytic asymmetric Friedel-Crafts alkylation reactions. The catalytic asymmetric synthesis of heterocyles is one of the most important goals in organic synthesis and medicinal chemistry. The second review provided by Ramon Rios and Jan Vesely illustrates the last efforts of chemical community in the development of new enantioselective organocatalytic methodologies for the synthesis of five and six heterocycles. Z.-H. Zhou, Y.-M. Wang and C.-C. Tang, State Key Laboratory of Elemento-Organic Chemistry, Institute of Elemento-Organic Chemistry, Nankai University, contribute to the third review, which deals with recent development in the asymmetric nucleophilic catalysis with tertiary phosphines as organocatalysts.....

Over the last few decades, the catalytic asymmetric Friedel-Crafts alkylation has become a powerful strategy that provides enantioenriched structural motifs of established value in medicinal chemistry or complex target synthesis. While the traditionally chiral Lewis-acid catalyzed Friedel-Crafts alkylation has been extensively reviewed in the literature, we focused this review on the recent advances on organocatalytic Friedel-Crafts alkylations. According to activation modes, this review is divided into three main sections, including 1) alkylations via iminium catalysis, 2) alkylations via SOMO catalysis, and 3) alkylations by chiral hydrogen-bond donors.

During last decade the field of Organocatalysis emerged as one of the cornerstones of organic asymmetric synthesis. The use of organocatalysis has some advantages such as metal free reactions, environmentally friendly conditions, does not need to use dry solvents or inert atmosphere, avoid the use of protecting groups, etc… For these reasons, several research groups have focused their efforts on the development of new organocatalytic methodologies that render the final products in excellent yields and stereoselectivities. Concretely, the organocatalytic synthesis of 5 and 6 membered heterocycles has attracted much attention. In this review we have the aim to describe the different organocatalytic methodologies developed since in the synthesis of 5 and 6 heterocycles.

Phosphines have recently become popular choices as nucleophilic catalysts in many asymmetric reactions, including: diastereoselective reactions, enantioselective reactions and other special type asymmetric reactions, such as kinetic resolution and desymmetrization. This mini-review presents recent advances in the application of nucleophilic phosphine organocatalysts for the preparation of chiral building blocks.

Over the past decade, chiral Lewis base-catalysed cycloadditions has brought about numerous methods for the enantioselective synthesis of carbocycles and heterocycles. This short review covers some of the advances made in the area of absolute stereocontrol in this higher order cycloaddition.

Asymmetric Mannich-type reactions are important organic transformations that provide excellent protocols for the synthesis of optically active nitrogen-containing compounds. This article provides an overview on the development of thiourea-catalyzed asymmetric Mannich or nitro-Mannich reactions including scope, limitations, and applications of different catalytic systems.

In recent years, asymmetric organocatalytic cascade reactions have emerged as a powerful and environmentally friendly tool for the rapid assembly of complex chiral molecules from simple and readily available starting materials in a single process, and have attracted much attention as the advantages of both cascade reactions and organocatalysis are merged. In this context, asymmetric organocatalytic cascade reactions catalyzed by the chiral amines are the most intensively studied as they are capable of activating the carbonyl compounds through enamine catalysis and iminium catalysis. Recently, chiral Bronsted acid catalysis has gained continuously increasing interest in the area of organocatalysis. With the development of asymmetric Bronsted acid catalysis, chiral Bronsted acidcatalyzed asymmetric cascade reactions have made considerable advancement. In this review, key development of asymmetric organocatalytic cascade reactions catalyzed by chiral Bronsted acids is summarized.