Comprehensive Review on Synthetic Approaches and Biological Activities of 1,3,4-Oxadiazole

Among the large variety of nitrogen and oxygen heterocycles, 1,3,4-oxadiazole, the scaffold, has attracted considerable attention owing to its ability to showing an extensive range of pharmacological actions. Therefore, significant efforts of organic chemists have been directed towards the construction of new drug candidates containing 1,3,4-oxadiazole subunits connected to a known pharmaceutical or a potential pharmacophore. This digest highlights recent publications on the various synthesis techniques of 1,3,4-oxadiazole and related compounds over the previous ten years (2011–2021). The purpose of this review is to learn about several ways for synthesizing oxadiazole. These heterocyclics are formed mainly by the cyclization reactions of various reactants under diverse circumstances. According to the literature investigations, they were given a high priority for their pharmacological significance, such as anticonvulsant, anticancer, antioxidant, anti-inflammatory, antibacterial, antidiabetic, etc.

Prins-Friedel-Crafts Cyclization: Synthesis of Diversely Functionalized Six-Membered Oxacycles

: Prins cyclization is a well-established synthetic protocol to generate a wide range of important oxygen heterocycles. It is a cyclization reaction performed by an oxocarbenium ion that undergoes an intramolecular pi-bond attack to construct a new carbon-carbon bond. When this cyclization process is conjugated with Friedel-Crafts reaction, it further expands the synthetic potential by fabricating two different carbon-carbon bonds in one single reaction. Different acid catalysts mediated, the coupled Prins-Friedel-Crafts reaction is conducted both in stepwise as well as in tandem fashion. In the stepwise route, three different reacting components were utilized whereas, the tandem methodology required proper modification of the initial substrate molecule. An array of allylic, propargylic, other related alkenols, and carbonyl reactants were employed to carry out the cyclization process. Several oxygenated heterocycles equipped with diverse functionalities were constructed in a stereoselective manner which again reinforced the significance of this cyclization protocol undoubtedly. The present mini-review highlights (on) the utilization of different one-pot stepwise Prins-Friedel-Crafts reactions and the subsequent development of cascade Prins-Friedel-Crafts cyclization process to furnish intricate molecular architectures of vital six-membered oxacycles.

Cross-linking of a polyketide synthase domain leads to a recyclable biocatalyst for chiral oxygen heterocycle synthesis

Cross-linking of the polyketide synthase domain AmbDH3 led to an active aggregate with improved properties for the chemoenzymatic synthesis of chiral oxygen heterocycles, such as recyclability and facile purification.

Synthesis of 2H-Chromenes: Recent Advances and Perspectives

As one type of chromenes, 2H-chromenes represent important oxygen heterocycles, which not only widely exist in natural products, pharmaceutical agents and biological relevant molecules, but also have been utilized broadly...