A chromatography-free one-pot, two-step synthesis of 1,2,4-thiadiazoles from primary amides via thiolation and oxidative dimerization under solvent-free conditions: a greener approach

An efficient and practical one-pot, two-step synthesis of 1,2,4-thiadiazoles from primary amides with Lawesson reagent (LR) and tert-butyl hydrogen peroxide (TBHP) without solvent is demonstrated for the first time. This groundbreaking and environmentally friendly approach utilises readily available starting materials and eliminates the use of traditional solvents in the reaction process. The broad substrate scope, excellent functional group tolerance in mild and metal-free conditions, quick conversion, and excellent yields are essential features of this methodology. All the compounds were purified without column chromatography.

Friedel-Crafts-Type Acylation and Amidation Reactions in Strong Brønsted Acid: Taming Superelectrophiles

In this review, we discuss Friedel-Crafts-type aromatic amidation and acylation reactions, not exhaustively, but mainly based on our research results. The electrophilic species involved are isocyanate cation and acylium cation, respectively, and both have a common ⁺C=O structure, which can be generated from carboxylic acid functionalities in a strong Brønsted acid. Carbamates substituted with methyl salicylate can be easily ionized to the isocyanate cation upon (di)protonation of the salicylate. Carboxylic acids can be used directly as a source of acylium cations. However, aminocarboxylic acids are inert in acidic media because two positively charged sites, ammonium and acylium cation, will be generated, resulting in energetically unfavorable charge-charge repulsion. Nevertheless, the aromatic acylation of aminocarboxylic acids can be achieved by using tailored phosphoric acid esters as Lewis bases to abrogate the charge-charge repulsion. Both examples tame the superelectrophilic character.

Recent advances in synthesis and medicinal chemistry of benzodiazepines

Benzodiazepines (BZDs) represent a diverse class of bicyclic heterocyclic molecules. In the last few years, benzodiazepines have emerged as potential therapeutic agents. As a result, several mild, efficient and high yielding protocols have been developed that offer access to various functionalized benzodiazepines (BZDs). They are known to possess a wide array of biological activities such as anxiolytic, anticancer, anticonvulsant, antipsychotics, muscle relaxant, anti-tuberculosis, and antimicrobial activities. The fascinating spectrum of biological activities exhibited by BZDs in various fields has prompted the medicinal chemist to design and discover novel benzodiazepine-based analogs as potential therapeutic candidates with the desired biological profile. In this review, an attempt has been made by to summarize (1) Recent advances in the synthetic chemistry of benzodiazepines which enable their synthesis with desired substitution pattern; (2) Medicinal chemistry of BZDs as therapeutic candidates with promising biological profile including insight of mechanistic studies; (3) The correlation of biological data with the structure i.e. structure-activity relationship studies were also included to provide an insight into the rational design of more active agents.

Asymmetric Synthesis of Multifunctionalized 2,3-Benzodiazepines by a One-Pot N-heterocyclic Carbene/Chiral Palladium Sequential Catalysis

We report the first example of the construction of chiral 2,3-benzodiazepine compounds which are of biologic and pharmaceutical relevance by asymmetric catalysis. Catalyzed by a thiazolium-derived carbene and a palladium-chiral bidentate phosphine complex in sequence, one-pot reaction between 1-(2-(2-nitrovinyl)aryl)allyl esters 1 with azodicarboxylates 2 took place efficiently at ambient temperature to produce 4-nitro-1-vinyl-1H-2,3-benzodiazepine-2,3-dicarboxylates 5 in good to excellent yields with an enantiomeric ratio of up to 95:5.