Four component reaction of aldehydes, isocyanides, Me3SiN3, and aliphatic alcohols catalyzed by indium triflate

Tetrazole derivatives in the management of neurological disorders: Recent advances on synthesis and pharmacological aspects

Neurological disorders are the leading cause of a large number of mortalities and morbidities. Nitrogen heterocyclic compounds have been pivotal in exhibiting wide array of therapeutic applications. Among them, tetrazole is a ubiquitous class of organic heterocyclic compounds that have attracted much attention because of its unique structural and chemical properties, and a wide range of pharmacological activities comprising anti-convulsant effect, antibiotic, anti-allergic, anti-hypertensive to name a few. Owing to significant chemical and biological properties, the present review aimed at highlighting the recent advances in tetrazole derivatives with special emphasis on their role in the management of neurological diseases. Besides, in-depth structure-activity relationships, molecular docking studies, and associated modes of action of tetrazole derivatives evident in in vitro, in vivo preclinical, and clinical studies have been discussed.

Sustainable Passerini-tetrazole three component reaction (PT-3CR): selective synthesis of oxaborol-tetrazoles

A sustainable catalyst- and solvent-free Passerini-tetrazole three component reaction (PT-3CR) has been developed for the selective synthesis of benzoxaborol-tetrazoles for the first time. The synthetic potential of oxaboroles was demonstrated towards various functionalized tetrazoles, which are otherwise difficult to achieve through conventional PT-3CR from aromatic aldehydes/ketones. The reaction features high practicality, broad substrate scope and excellent yields (80-98%). Preliminary results of the asymmetric PT-3CR are also shown for the synthesis of chiral benzoxaboroles.

Tetrazoles via Multicomponent Reactions

Tetrazole derivatives are a prime class of heterocycles, very important to medicinal chemistry and drug design due to not only their bioisosterism to carboxylic acid and amide moieties but also to their metabolic stability and other beneficial physicochemical properties. Although more than 20 FDA-approved drugs contain 1 H- or 2 H-tetrazole substituents, their exact binding mode, structural biology, 3D conformations, and in general their chemical behavior is not fully understood. Importantly, multicomponent reaction (MCR) chemistry offers convergent access to multiple tetrazole scaffolds providing the three important elements of novelty, diversity, and complexity, yet MCR pathways to tetrazoles are far from completely explored. Here, we review the use of multicomponent reactions for the preparation of substituted tetrazole derivatives. We highlight specific applications and general trends holding therein and discuss synthetic approaches and their value by analyzing scope and limitations, and also enlighten their receptor binding mode. Finally, we estimated the prospects of further research in this field.

Organic Synthesis Using Environmentally Benign Acid Catalysis

Recent advances in the application of environmentally benign acid catalysts in organic synthesis are reviewed. The work includes three main parts; (i) description of environmentally benign acid catalysts, (ii) synthesis with heterogeneous and (iii) homogeneous catalysts. The first part provides a brief overview of acid catalysts, both solid acids (metal oxides, zeolites, clays, ion-exchange resins, metal-organic framework based catalysts) and those that are soluble in green solvents (water, alcohols) and at the same time could be regenerated after reactions (metal triflates, heteropoly acids, acidic organocatalysts etc.). The synthesis sections review a broad array of the most common and practical reactions such as Friedel-Crafts and related reactions (acylation, alkylations, hydroxyalkylations, halogenations, nitrations etc.), multicomponent reactions, rearrangements and ring transformations (cyclizations, ring opening). Both the heterogeneous and homogeneous catalytic synthesis parts include an overview of asymmetric acid catalysis with chiral Lewis and Brønsted acids. Although a broad array of catalytic processes are discussed, emphasis is placed on applications with commercially available catalysts as well as those of sustainable nature; thus individual examples are critically reviewed regarding their contribution to sustainable synthesis.

Multicomponent synthesis of hydrazino depsipeptides

Hydrazino depsipeptides, a new class of backbone extended peptidomimetics were prepared by the Passerini reaction of α-hydrazino acids, carbonyl compounds and isocyanides.

Isocyanide-based multicomponent reactions in the synthesis of heterocycles

In this review, we update our previous presentation, underscoring the recent applications of isocyanides as privileged synthons in the synthesis of various heterocyclic compounds, especially focused on those synthesizedviamulticomponent reactions.

A one-pot O-sulfinative Passerini/oxidation reaction: synthesis of α-(sulfonyloxy)amide derivatives

We have developed a one-pot O-sulfinative Passerini/oxidation reaction, in which a combination of an aldehyde, an isocyanide, and a sulfinic acid react, followed by the addition of mCPBA as an oxidant to give the corresponding α-(sulfonyloxy)amides in high yields. This reaction is the first reported demonstration of an isocyanide-based multicomponent reaction using a sulfinic acid in place of a carboxylic acid. A wide range of aldehydes and isocyanides are applicable to this reaction.

Synthesis of tetrazoles via isocyanide-based reactions

This article provides an overview of the contributions and advances in the synthesis of tetrazoles via isocyanide-based reactions.

A one-pot O-phosphinative Passerini/Pudovik reaction: efficient synthesis of highly functionalized α-(phosphinyloxy)amide derivatives

A one-pot O-phosphinative Passerini/Pudovik reaction has been developed, based on reacting aldehydes, isocyanides, and phosphinic acids followed by the addition of second aldehydes to form the corresponding α-(phosphinyloxy)amide derivatives. This is the first reported instance of a Passerini-type, isocyanide-based multicomponent reaction using a phosphinic acid instead of a carboxylic acid. The nucleophilicity of the phosphinate group allows a subsequent catalytic Pudovik-type reaction, affording the highly functionalized α-(phosphinyloxy)amide derivative in high yield. A wide range of aldehydes and isocyanides are applicable to this reaction.