Current Organic Chemistry - Volume 27, Issue 7, 2023

Heterocycles are organic compounds, the most important pharmaceutical skeleton widely distributed in nature. Many of them possess medicinal as well as pharmacological activities. Pyrroles are well-known five-member-privileged scaffolds with pharmaceutical potential. Pyrrole is the component of complex macrocycles, including porphyrins of heme and chlorophylls. Nowadays, the development of microwave-supported synthetic strategies for such biologically relevant heterocycles is an important objective. Microwave-induced pyrrole synthesis has become an environmentally benign route in organic transformation with reduced reaction time and high yields. This mini-review focuses on the eco-friendly microwaveinduced synthesis of pyrroles, their derivatives, and their potential pharmacological applications, covering literature up to 2022.

Selenium metal acts as an essential nutrient in many selenoproteins. Various selenium- containing compounds are reported to possess a broad range of biological activities. In many commercially available drug molecules, selenium plays an important role. As a result, during the last two decades, organoselenium chemistry has expanded widely. A huge number of methods have been reported for the synthesis of structurally diverse organoselenium compounds under various reaction conditions. On the other hand, ultrasound-assisted protocols are found much more advantageous over traditional thermal methods in terms of reaction times, yields, product selectivity, purity of the products etc. In many occasions, it was found that ultrasound plays a pivotal role in achieving the desired products in high yields. In this review, we have summarized the recent literature on the ultrasound-assisted synthesis of various organoselenium scaffolds under diverse reaction conditions.

Important progress in the transfer of organic reactions from solution conditions to automated solid-state synthesis was published a quarter of a century ago. Since then, ball-milling organic reactions have been slowly accepted by the chemical community as an additional synthetic tool, and the area of its application is rapidly expanding. These developments in mechanochemical synthesis are illustrated with selected literature examples.

The increasing environmental pollution and its detrimental impact on the ecosystem made scientists develop new chemical strategies involving eco-friendly chemicals, solvents, catalysts, atom-economical procedures, and alternative energy sources. Among these, deep eutectic solvents (DESs) are primarily low-melting mixtures of quaternary ammonium salt and hydrogen-bond acceptors. Low toxicity, easy preparation, low cost, biodegradability, low vapor pressure, and recyclability are the main advantages of DESs. Multicomponent reactions (MCRs) are efficient procedures for generating new libraries with high structural complexity. MCRs can give one product from at least three components in a single operation with high bond-forming efficiency, shortness, and structural diversity. Compared with conventional methodologies, the structural diversity, the convergent and atom economic character, the easy applicability of a one-pot operation, the accessibility to complex molecules, the minimized waste formation, and high selectivity are the main advantages of one-pot multicomponent reactions. The application of MCRs in eutectic solvents not only simplifies procedures but also displays more positive effects on the protection of the ecosystem.

Different intermediates are key molecules to synthesize high-added value bioactive and pharmacology molecules such as propargylamines may be synthesized in several ways using catalysts in homogeneous and heterogeneous conditions. This review presents the catalysts which are used in the A3, AHA, and KA2 coupling reactions to afford propargylamines. It also provides a classification of all the propargylamines known up to date in the literature and their reported synthesis conditions.