Chemoselective synthesis of fully substituted pyrroles: Via a one-pot four-component isocyanide-based reaction

Small-ring heterocycles comprising pyrrole and pyrazole are well known for their rich biological properties. In this article, an efficient green sonochemical approach was designed for the synthesis of novel, fully substituted pyrroles connected to pyrazole scaffolds via a one-pot, four-component isocyanide-based sequential reaction. This reaction was carried out using various 5-amino-pyrazoles, aldehydes, dialkyl acetylenedicarboxylates and isocyanides for the synthesis of fully functionalized pyrroles with high chemoselectivity in the presence of a catalytic amount of PTSA·H2O, in good to excellent yields under ultrasound irradiation. This waste-free (-H2O) reaction exhibited a high atom economy and step economy via creating four new bonds, including two C-N and two C-C bonds, and the formation of two five-member heterocycles which are connected in a single operation. The mechanism of this four-component domino process involved sequential imination-dipolar cyclization-[1,5]-H shift reactions. The synthesized compounds possess interesting fluorescence features, and the bioactive scaffolds might attract great interest in the fields of clinical diagnostics and biomedical research in the future. This journal is © The Royal Society of Chemistry

Synthesis of Depsipeptides via Isocyanide-Based Consecutive Bargellini-Passerini Multicomponent Reactions

An efficient and straightforward approach has been established for the preparation of a new class of depsipeptide structures via isocyanide-based consecutive Bargellini-Passerini multicomponent reactions. 3-Carboxamido-isobutyric acids bearing an amide bond were obtained via Bargellini multicomponent reaction from isocyanides, acetone, and chloroform in the presence of sodium hydroxide. Next, via a Passerini multicomponent-reaction strategy, a new class of depsipeptides was synthesized using the Bargellini reaction products, isocyanides, and aldehydes. The depsipeptides thus prepared have more flexible structures than their pseudopeptidic analogues. © 2021 Georg Thieme Verlag. All rights reserved

Consecutive Betti/Bargellini multicomponent reactions: an efficient strategy for the synthesis of naphtho[1,2-f][1,4]oxazepine scaffolds

An efficient and convenient approach has been developed for the synthesis of naphtho[1,2-f][1,4]oxazepine structures based on the consecutive Betti/Bargellini multicomponent reactions. Aminobenzylnaphthols were prepared from 2-naphthol, aromatic aldehydes, and 2-aminopyridine via the Betti reaction, and then, naphtho[1,2-f][1,4]oxazepine derivatives were synthesized using the Betti reaction products, chloroform, and aliphatic ketones in the presence of sodium hydroxide via Bargellini multicomponent reactions. A significant aspect of this work is the construction of novel oxazepine-based scaffolds with potential pharmaceutical interest from cheap and readily available starting materials in moderate yields. Graphic abstract: [Figure not available: see fulltext.]. © 2021, Institute of Chemistry, Slovak Academy of Sciences

Highly efficient azido-Ugi multicomponent reactions for the synthesis of bioactive tetrazoles bearing sulfonamide scaffolds

Recent studies revealed that the contribution of the different bioactive scaffolds in one structure creates modern drugs/compounds with unique synergistic biological properties. In this regard, thanks to the interesting biological and medicinal properties of sulfonamide and tetrazole skeletons, this study describes the engagement of sulfonamides in the Ugi tetrazole reaction to access a library of tetrazole bearing sulfonamide. This four-component reaction was performed in a one-pot among available starting material, i.e., an isocyanide, a sulfonamide, an aldehyde and sodium azide in MeOH at 45 °C using ZnCl2 as a catalyst, for the synthesis of very versatile products with high atom economy and yields. The key point in this strategy is the formation of an intermediate Schiff base and its activation in the azido-Ugi reaction by a Lewis acid catalyst. Importantly, all products are purified through the group-assisted purification (GAP) chemistry, which can avoid traditional purification such as recrystallization and chromatography methods. Also, the docking study between the synthesized compounds and human serum albumin (HSA) was stimulated to theoretically rationalize their biological activity and potential binding interactions. © 2021 Elsevier Lt