Current Organic Chemistry - Volume 25, Issue 5, 2021

The synthesis of ester-containing heterocyclic compounds via multicomponent reaction is one of the preferable processes in synthetic organic chemistry and medicinal chemistry. Compounds containing ester linkage have a wide range of biological applications in the pharmaceutical field. Therefore, many methods have been developed for the synthesis of these types of derivatives. However, some of them are carried out in the presence of toxic solvents and catalysts, with lower yields, longer reaction times, low selectivities, and byproducts. Thus, the development of new synthetic methods for ester synthesis is required in medicinal chemistry. As we know, multicomponent reactions (MCRs) are a powerful tool for the one-pot ester synthesis, so in this article, we have reviewed the recent developments in ester synthesis. This work covers a selected explanation of methods via multicomponent reactions to explore the methodological development in ester synthesis.

The deep eutectic mixtures (DESs), introduced as a novel alternative to usual volatile organic solvents for organic transformations, have attracted tremendous attention of the research community because of their low cost, negligible vapour pressure, low toxicity, biodegradability, recyclability, insensitivity towards moisture, and ready availability from bulk renewable resources. Although the low melting mixture of dimethyl urea (DMU)/L-(+)- tartaric acid (TA) is still in infancy, it is very effective as it plays multiple roles such as solvent, catalyst and/or reagent in the same pot for many crucial organic transformations. These unique properties of the DMU/TA mixture prompted us to provide a quick overview of where the field stands presently and where it might be going in the near future. To our best knowledge, no review dealing with the applications of a low melting mixture of DMU/TA appeared in the literature except the one published in 2017, describing only the chemistry of indole systems. Therefore, we intended to reveal the developments of this versatile, low melting mixture in the modern organic synthesis since its first report in 2011 by Köenig’s team to date. Hopefully, the present review article will be useful to the researcher working not only in the arena of synthetic organic chemistry but also to the scientists working in other branches of science and technology.

N-Methyl-D-aspartate (NMDA) receptors, together with AMPA and kainite receptors, belong to the family of ionotropic glutamate receptors. NMDA receptors play a crucial role in neuronal plasticity and cognitive functions. Overactivation of those receptors leads to glutamate-induced excitotoxicity, which could be suppressed by NMDA antagonists. Dizocilpine was firstly reported in 1982 as an NMDA receptor antagonist with anticonvulsive properties, but due to serious side effects like neuronal vacuolization, its use in human medicine is restricted. However, dizocilpine is still used as a validated tool to induce the symptoms of schizophrenia in animal models and also as a standard for comparative purposes to newly developed NMDA receptor antagonists. For this reason, the synthesis of dizocilpine and especially its more active enantiomer (+)-dizocilpine is still relevant. In this review, we bring a collection of various synthetic approaches leading to dizocilpine and its analogues.

This review summarizes the transition metal-catalyzed direct C–H functionalization of quinazolinones and quinazolines through C-C, C-N and C-O bond formations. It focuses mainly on the C-H (sp² or sp³) bond arylation, amination, sulfamidation, acetoxylation, halogenation, annulation of quinazolinones and quinazolines. This review illustrates the scope of C-H activation and functionalization of various quinazolinone and quinazoline derivatives.

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 which 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 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.