Current Organic Chemistry - Volume 23, Issue 7, 2019

As an alternative to increasingly depleted traditional petroleum fuel, bio-oil has many advantages: high energy density, flexibility, easy storage and transportation. Nevertheless, bio-oil also presents some unwanted characteristics such as high viscosity, acidity, oxygen content and chemical instability. The process of bio-oil upgrading is necessary before utilization as transportation fuels. In addition, the bio-oil has low effective hydrogen/ carbon molar ratio (H/Ceff) which may lead to coke formation and hence deactivation of the catalyst during the upgrading process. Therefore, it seemed that co-refining of biooil with other higher hydrogen-containing feedstocks is necessary. This paper provides a broad review of the bio-oil upgrading with high hydrogen-containing feedstocks to produce transportation fuels: chemistry, catalyst, and engineering research aspects were discussed. The different thermochemical conversion routes to produce bio-oil and its physical-chemical properties are discussed firstly. Then the bio-oil upgrading research using traditional technologies and common catalysts that emerged in recent years are briefly reviewed. Furthermore, the applications of high H/Ceff feedstock to produce high-quality of bio-oil are also discussed. Moreover, the emphasis is placed on co-refining technologies to produce transportation fuels. The processes of co-refining bio-oil and vacuum gas oil in fluid catalytic cracking (FCC) unit for transportation fuels from laboratory scale to pilot scale are also covered in this review. Co-refining technology makes it possible for commercial applications of bio-oil. Finally, some suggestions and prospects are put forward.

Recent advances in high-throughput, automated techniques combined with the identification of new therapeutic targets in genome sequencing and molecular biology have generated a need for a large collection of diverse heterocyclic scaffolds. This inspires toward the development of novel reaction sequences and linking strategies to generate libraries of diverse simple to complex heterocyclic systems. In this regard, combinatorial chemistry has emerged as an excellent technology platform for the rapid assembly of building blocks to synthesize complex molecular structures with great ease in a few synthetic steps. By means of the implementation of high-throughput screening for the biological evaluation of hits and leads, combinatorial libraries have become important assets in drug discovery and development. In the last two decades, the cyclorelease strategy that minimizes the chemical and tethering implications by releasing the intact desired target molecule in the final step of reaction has attracted much attention. Recently, a particular interest is developing in linking strategies, where loading and cleavage steps contribute to the complexity of the target structure rather than only extraneous manipulations. This review summarises the practical and high-yielding approaches of solid phase combinatorial synthesis for diverse high-purity heterocyclic skeletons of pharmacological importance involving the cycloelimination strategy.

Interlayer dielectrics with low dielectric constant are the key to unlock the high arithmetic speed of integrated circuit, one of the kernels of modern industry. Polybenzoxazine, derived from benzoxazine precursor, is a new generation of phenolic resin that is considered as an ideal potential candidate for electronic materials due to its unique properties. However, for developing higher speed supercomputers, the dielectric property of conventional polybenzoxazine becomes the Achilles’ heel. Fortunately, the versatile design flexibility of benzoxazine chemistry provides the possibility to reduce the dielectric constant of the material. This review focuses on the recent attempts to synthesize low dielectric benzoxazine and the properties of the corresponding polybenzoxazine materials. Methods including fluorination, hydrocarbon introduction, heterocycle generation, molecular weight tailoring, copolymerization and organic-inorganic hybridization are introduced.

We herein describe the first review which aims to focus soberly the various synthetic methods and chemical reactions of chloroquinoline-3-carbonitrile derivatives. The reactions are subdivided into groups that cover reactions of chloro substituent at 2 or 4 and 2,4 positions, as well as cyano substituent at 3 position and reactions which involve both groups. Most types of reactions have been successfully applied and used in the production of biologically active compounds.

An important approach to the development of new antitumor agents is the synthesis of conjugates containing two or more structural units. Taking this into consideration, vindoline derivatives were coupled with triphenylphosphine, to afford the expected phosphonium salts. The new hybrid entities were characterized by NMR spectroscopy, and their anticancer activity was also evaluated.