Current Organic Chemistry - Volume 22, Issue 25, 2018

Background: The synthesis of seven-membered heterocycles is a growing field in order to explore their biological and pharmaceutical importance. 1,3,4- Thiadiazepinesare are a notable class of heterocyclic compounds with remarkable biological importance. 1,3,4-Thiadiazepines have been reported to have an exceptional range of biological activities such as anti-HIV, biocidal, antimicrobial and generating agents and used in drug design processes. Objective: The present study highlights structural studies, chemical reactivity, synthetic methods of monocyclic and poly-fused heterocycles and biological significance of heterocyclic compounds incorporated 1,3,4-thiadiazepine skeleton. Conclusion: The purpose of this assessment is to discuss the chemical assembly, reactivity and synthetic procedures of the title compounds up till now. The reaction mechanisms are discussed, as well as, the biological applications of the target compounds. This study will help researchers in the fields of organic and medicinal chemistry to design and implement new procedures for the constructions of novel biological components.

Allylic and benzylic brominations are of paramount importance in organic synthesis. They give rise to many valuable synthons leading to the production of fine chemicals, agrochemicals and pharmaceuticals. A great many bromination methods have thus been developed to conduct the titled reactions under different circumstances. The need for environmentally benign conditions to circumvent drawbacks associated with original methods has significantly enhanced the advance in this field. Herein, only methods for benzylic brominations are reviewed and outlined because alkylbenzenes are more often chosen as the model substrates for new methods development.

Chiral ligands perform the vital role in enantioselective transition-metal mediated reactions. The accomplishment of N-based chiral ligands is due to the inherent air stability, electron-rich, neutral ligands for homogeneous catalysis. Above all, the easy access and diversity in the core structure as a template for asymmetric reactions led to the experimentation and establishment of diverse chiral N-based backbone as stereodirecting ligands for a variety of asymmetric reactions. The wide efficacy of these ligands is established by the high enantioselectivity persuaded in a variety of transition metal mediated enantioselective reactions, for instance, redox reactions, cycloadditions and carbonheteroatom and carbon-carbon bond making reactions. Due to the modular architecture and the ease of access from the chiral pool, the N-based chiral ligands are readily available. In this review, we will highlight selected examples of N-based chiral ligands which have endowed high enantioselectivity in Pd-mediated asymmetric transformations. The enantioselective aptitude of chiral N-based ligands in Pd-catalyzed reactions is demonstrated largely by the nature of coordinating atoms and the structure of the ligand. Using N-based chiral ligands, excellent yields and enantioselectivities have been obtained. The ligand classification in this review is based upon the ligand framework, hoping to inspire the development of next-generation N-based chiral ligands with innovative enantioselective transformations.

The emergence of multidrug-resistant (MDR) pathogens and cancers alarms the world for the urgent exploration of new therapeutic drugs to treat the superbugs and cancer patients. Since the ancient time, natural products and/or their derivatives have become continuous sources of leading commercialized pharmacological compounds that are used as antibiotics and antitumor agents. An unexplored source of natural products, lichen, currently has evolved into a propitious source of diverse secondary metabolites with various bio-activities including anticancer and antimicrobial, offering the abundant potentiality for future drugs. Herein, we summarized the progress in the discovery of structurally diverse anticancer compounds (C1-C85) with their plausible mode of action and antimicrobial compounds (M1-M112) from lichen and lichen-derived fungi together with their biodiversity. This review covers natural products discussed in literature from January 1985 to December 2017.

Five different model reactions (photodecarboxylation, inter- and intramolecular [2+2] cycloadditions, TiO2 photocatalytic reduction and type II photooxygenation) were investigated in the advanced Vapourtec UV-150 photo reactor with their conversion and throughput potentials reported. Compared to known batch reactions in laboratory reactors, significantly higher calculated productivities were achieved despite a rather small 10 mL reactor coil. The device enables rapid, convenient, reliable and reproducible flow photochemistry studies across the entire wavelengths spectrum and on flexible scales.