Current Organic Chemistry - Volume 18, Issue 3, 2014

Anthrax is an infectious disease associated with a high death rate in the absence of treatment. To be effective, antibiotics must be administered early after infection and during a prolonged period, therefore, designing vaccines is a valuable alternative. With the currently marketed anthrax vaccines being considered less than optimal, the development of novel formulations is strongly encouraged by health and government authorities. Along this line the recent disclosure of the structure of several oligosaccharides expressed at the surface of Bacillus anthracis, the etiological agent of anthrax, has boosted the development of a glycoconjugate-based vaccine. This review describes the different strategies which have been envisaged to prepare these carbohydrate antigens as well as analogs thereof. The data on antigenicity and immunology generated by these derivatives are also detailed. Finally, future prospects on the development of anthrax glycoconjugate vaccines are discussed.

The review summarizes the use of metal nanoparticles as catalysts in cross-coupling reactions. Nanoparticle-sized catalysts are used in a variety of reactions, however, this chapter will focus on their use in the following cross-coupling reactions: Suzuki-Miyaura, Mizoroki-Heck, Sonogashira, Ullmann and Stille. Catalysts in nanoparticle size are often supported on other materials, referred to as catalyst supports. The various catalyst supports utilized for nanoparticles used in cross-coupling reactions will also be presented.

Methodology of the synthesis of higher carbon sugars containing > 10 carbon atoms in the chain is reviewed. The emphasis is put on such derivatives which can be (or are) easily converted into higher alditols.

Iodocyclization reactions are acquiring an increasing importance in organic synthesis, in view of the possibility to obtain iodine- containing heterocycles starting from readily available acyclic substrates under mild reaction conditions. Various aspects of these iodocyclization reactions have been recently reviewed, including the application of iodocyclization processes to the synthesis of natural products, heterocyclic derivatives, and carbocyclic derivatives, as well as the construction of heterocyclic libraries. The present mini-review is intended to highlight some very recent (from 2010 to the beginning of 2013) and particularly interesting examples of the synthesis of heterocyclic derivatives by the iodoheterocyclization of functionalized alkynes. The iodoheterocyclization of acetylenic substrates bearing a suitably placed nucleophilic group is a powerful method for the direct synthesis of unsaturated iodinecontaining heterocycles. The products obtained can be further elaborated through various cross-coupling reactions (such as Heck, Suzuki- Miyaura, and Sonogashira reactions), making the process of particular synthetic interest. Moreover, the iodocyclization reaction is carried out under very mild reaction conditions (generally room temperature), using a simple source of electrophilic iodine, such as I2, ICl, or NIS (N-iodo-succinimide), usually in the presence of a base to help buffer the acid produced by deprotonation of the nucleophilic functional group present in the substrate. The mini-review is divided into three parts: Synthesis of iodine-containing oxygen heterocycles; Synthesis of iodine-containing nitrogen heterocycles; and Synthesis of iodine-containing sulfur and selenium heterocycles. The examples shown in the mini-review demonstrate that the iodoheterocyclization of functionalized alkynes is a wide-scope synthetic methodology, which can also be useful for the synthesis of biologically active molecules and complex natural products.

Heterocyclic 1,2,4-triazole derivatives possess unusually spacious potentiality as medicinal agents, agricultural chemicals, functional materials, ionic liquids, supramolecular catalysts as well as artificial enzymes and receptors for supramolecular recognition and biomimetic catalysis, and their various researches and developments have been being a quite rapidly developing and active highlight topic with an infinite space. Numerous efforts have been directed toward various types of possible applications of 1,2,4-triazole-based compounds and a lot of important progress has been made, especially their preparations have attracted increasing attention. This review systematically summarized the recent advances in the syntheses of 1,2,4-triazole derivatives, including: (1) Cyclizations to form triazole ring; (2) Transformations of heterocyclic compounds to construct triazole ring; (3) Substitutions on 1,2,4-triazole ring; (4) Structural modifications in side chains of 1,2,4-triazole ring. It was hoped that this review would be helpful for the design and development of highly efficient preparation of 1,2,4-triazole derivatives with various sorts and varieties of extensively potential applications in medicine, agriculture, chemistry, materials, supramolecular sciences and so on.

In this review, a group of two-dimensional (2D) self-assembled supramolecular chemical reactions observed by our laboratory are discussed. Our focuses mainly involve: 1) Surface supramolecular chemical reactions tuned by photo-stimulation; 2) Regulation of surface-confined nanostructure with metal-ligand coordination; 3) Construction of 2D supramolecular nanostructures through Schiff-base reaction observed by STM. It is envisioned that studies on these reactions are beneficial for us to understand the mechanism of supramolecular self-assembly process and impose further control over them.