Current Organic Synthesis - Volume 8, Issue 1, 2011

C-Heteroatom couplings have become increasingly trendy in the past few years and are currently present in many organic synthetic protocols for the preparation of a plethora of chemical products and intermediates with a wide range of applications in different areas including fragrances, pharmaceuticals, agrochemicals and dyes. A remarkable degree of development in importance of such processes in Organic Synthesis has been recently revealed with improved protocols, reactions conditions and methodologies that allow a better separation and recycling of reagents and products upon reaction completion, alternative reaction media (e.g. aqueous protocols, microwaves, mechanochemistry, etc.) and many others reported to date. The second part of this special issue is dedicated to the latest developments in C-Heteroatom couplings in Organic Synthesis, including less extended reactions such as C-N, C-S and related C-Heteroatom couplings for the synthesis of natural products, fine chemicals and pharmaceuticals. It was the aim of the editor to commision a variety of couplings in order to compile a well balanced issue that includes both general overviews and detailed specific topics to make it suitable for a broader audience. These will include C-H activation as well as a range of C-N, C-S and other C-Heteroatom couplings (e.g. C-Se, CTe) from worlwide respected and well-known leaders in the field including Profs. Beletskaya (Russia) and Fairlamb (UK) as well as emerging young researchers such as Dr. Senra (Brazil). The editor was delighted to assemble such an outstanding list of contributors for the special issue and would like to thank deeply the authors and the journal for their cooperation and assistance during the past months. The editor sincerely hopes part 2 of this special issue on C-Heteroatom couplings will be able to attract the attention of many readers in the field as well as introduce many others in the fascinating world of coupling chemistry and look forward to contemplating further improvements in this area inspired (why not) by some of the contributions included in this issue. With very best wishes for the success of the special issue.

Non-catalytic and catalytic addition reactions were compared in this review, with a special attention paid to the factors controlling selectivity and yields. The scope and limitations of Ni, Pd, Pt, Rh and Au catalysts for the formation of C-S, C-Se and C-Te bonds were discussed with an impact of development of Green chemical methods.

Transition-metal-catalyzed coupling of amines with aryl halides (or pseudo-halides) has evolved as the most versatile method available to forge carbon-nitrogen bonds. However, due to economic and environmental concerns, the quest for more attractive protocols in both academic and industrial domains has been pursued. In this review, we have summarized recent developments in the use of alternative methodologies, regarding non-conventional reaction medium, activation source and catalyst system, which can be considered promising for C-N cross-coupling reactions (Buchwald- Hartwig, Ullmann and correlates).

Organocopper chemistry has long been known to be powerful synthetic methodology leading to the generation of C-C, C-O, C-N, C-S and C-X bonds. Advances in catalytic and stoichiometric organometallic reactions for the formation of C-C bonds from unfunctionalised arenes, e.g. by activation-functionalisation of a C-H bond, provides diverse and applicable reaction conditions for direct functionalisation. This review covers the background, applications and recent advances made in the area of aromatic C-X/C-H-bond couplings promoted by copper and copper/palladium mixed systems. The efficacy and scope of these reactions are discussed and the different methodologies are placed into context. Mechanistic considerations and evidence are highlighted at appropriate junctures in the review.

A review dealing with iminosugars as inhibitors of α-L-fucosidases is presented. The different synthetic approaches for the preparation of the most relevant ones as well as their inhibitory properties are presented.

Dehydroaltenusin has been isolated from Alternaria tenuis and other fungal species. It exhibits various biological activities such as growth inhibition of wood-damaging fungi, inhibition of calmodulin-dependent myosin light chain kinase, anti-HIV activity, and inhibition of mammalian DNA polymerase α (pol α). These significant biological activities, as well as the unique structural properties of dehydroaltenusin, have stimulated considerable interest in its synthesis. In this review, we summarize the synthesis and structural analysis of dehydroaltenusin and its derivatives. We also focus on the structure-activity relationships of dehydroaltenusin as a mammalian pol α inhibitor. Dehydroaltenusin specifically inhibits mammalian pol α, an enzyme that plays an important role in DNA replication and cell division. The human genome encodes 14 pols that control cellular DNA synthesis, and synthetic dehydroaltenusin derivatives, which are specific inhibitors of mammalian pol α, are useful tools and molecular probes for distinguishing pols and for clarifying their biological and in vivo functions. Moreover, these compounds might be potentially useful as anti-cancer chemotherapeutic drugs for in vivo studies.