Current Organic Chemistry - Volume 22, Issue 3, 2018

The present review summarizes the up to date developments on organobicyclo- bases namely 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU) and 1,5,7-triazabicyclo-[4,4,0]-dec-1-ene (TBD) catalyzed one-pot multi-component synthesis of biologically relevant heterocycles.

The combination of advantages of multicomponent reactions (MCRs) and magnetic nano catalysts is going to be an emerging and strategic area and is an ideal blend for the development of sustainable methodologies in organic synthesis in green and benign media. This review focuses on the synthesis, functionalization, and application of organic-inorganic hybrid magnetic nanoparticles as novel task-specific catalysts on multicomponent reactions (MCRs) in recent years. So, properly magnetic nanoparticles can be used as building blocks for the fabrication of various functional moieties, and their application in catalysis of MCRs will be briefly reviewed. The heterogenization of the catalyst using magnetic nanoparticles allows it to be recovered and reused using an external magnet. The approach to magnetic separation is not only easy, cost-effective, favorable for work-up procedures and industrial applications, but also is usually more effective than filtration or centrifugation as it diminishes the loss of the catalyst.

Background and Methodology: A series of pyridazino[5,4,3-de][1,6]naphthyridine derivatives of a new ring system (11a-k, 29a,b) were synthesized via novel multicomponent reaction under high pressure from 2-phenylhydrazono derivatives (1a-d), malononitrile and aromatic aldehydes (10a-h) or acetone (28). Conclusion: The structure of reaction products could be established by X-ray crystallography and a mechanism of reaction is proposed.

Methyl α-cyano β-(hetero)aryl acrylates are excellent substrates for CAL-B catalyzed aminolyses. However, upon concatenation of the substrate Knoevenagel condensation (of (hetero)aryl carbaldehydes and methyl cyano acetate) and the CAL-B catalyzed aminolysis, an interesting bifurcating domino Knoevenagel-CAL-B catalyzed aryl methylaminolysis/hydrolysis reaction furnishing either amides or salts in the sense of a three-component process was found. The enzyme mediated acylative bifurcation of water vs benzyl amines depends on the substitution pattern of the aldehydes and on the presence or absence of a water scavenger. In the former case, amidation is favored while in the latter case hydrolysis/salt formation prevails.

Background: Spiro[4.5]decenones are privileged structural motifs occurring in various biologically active natural and unnatural compounds. Moreover, they are very important intermediates in organic synthesis. Therefore, the development of novel onepot protocols for the synthesis of these synthetically challenging spirocyclic compounds that benefit from simple, inexpensive, and readily available starting materials continues to be a target of intense interest. In recent years, tremendous efforts have been made toward the construction of titled compounds form cheap and readily accessible N-arylpropiolamide derivatives through intramolecular ipso-cyclization strategy. Objective/Methodology: This review highlights recent advances in this explosive growing research area from the year 2005 to 2017. Conclusion: The review is divided into three major sections. The first section focuses exclusively on ipsohalocyclization approaches. The second section will discuss oxidative radical ipso-cyclizations. The third will cover catalytic ipso-cyclizations. Mechanistic aspects of the reactions are considered and discussed in detail.

Background: In the last few decades, research into boron-containing compounds (BCCs) has notably increased in medicinal chemistry. Multiple maladies are now targeted by means of BCCs. Since bioinformatics tools have become a common and efficient methodology for drug design and materials science, their application to the study of BCCs is expected to intensify. Objective: This review compiles the use of computational technology to elucidate the chemical-biological effects of BCCs, whether coming from natural sources or drug development strategies. Results: A broad range of computational approaches facilitate pharmacochemical analysis of BCCs. The most focusing on the essential parameters of a boron atom, the reasons for an experimental event, and the shared pharmacodynamics, pharmacokinetics or toxic effects of components of a group of BCCs. Conclusions: Some studies have examined the properties of the boron atom in molecules for designing drugs and biomaterials, others have been aimed to identify the best quantitative structure-activity relationship for a specific target, but lacking some experimental and theoretical data limit the use of boron in theoretical assays. A final remark is made as to the potential impact on BCC research that could result from advances in bioinformatics.