A facile synthesis of aminomethylene bisphosphonates catalyzed by ytterbium perfluorooctanoate under ionic liquid condition

α-Aminoazoles/azines: key reaction partners for multicomponent reactions

Aromatic α-aminoazaheterocycles are the focus of significant investigations and exploration by researchers owing to their key role in diverse biological and physiological processes. The existence of their derivatives in numerous drugs and alkaloids is due to their heterocyclic nitrogenous nature. Therefore, the synthesis of a structurally diverse range of their derivatives through simple and convenient methods represents a vital field of synthetic organic chemistry. Multicomponent reactions (MCRs) provide a platform to introduce desirable structure diversity and complexity into a molecule in a single operation with a significant reduction in the use of harmful organic waste, and hence have attracted particular attention as an excellent tool to access these derivatives. This review covers the advances made from 2010 to the beginning of 2020 in terms of the utilization of α-aminoazaheterocycles as synthetic precursors in MCRs.

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

In this review we focus on applications of alkyl orthoesters as valuable and efficient substrates to perform various classes of two-component and multi-component organic reactions. The article has classified them according to two aspects, which are: (i) a focus on the reaction medium (solvent-free conditions, aqueous media, and organic solvents); and (ii) an examination of product structures. Reaction accomplishment under solvent-free conditions is an eco-friendly process with the absence of volatile toxic solvents, which puts it in line with green chemistry goals. Water is an interesting choice in organic transformations due to its inexpensiveness and safety. The authors hope their assessment will help chemists to attain new approaches for utilizing alkyl orthoesters in various organic synthetic methods. The review covers the corresponding literature up to the beginning of 2020.

In this review we focus on applications of alkyl orthoesters as valuable and efficient substrates to perform various classes of two-component and multi-component organic reactions.

Multicomponent Facile Synthesis of Highly Substituted [1,2,4]Triazolo[1,5-a] Pyrimidines

A simple and convenient method for one-pot synthesis of a series of potentially biologically active [1,2,4]triazolo[1,5- a]pyrimidine-6-carboxamide derivatives has been developed in solvent-free conditions using maltose as a commercially available, cheap and eco-friendly catalyst. The salient features of the present protocol are mild reaction conditions, good to excellent yields, high atom economy, benign environmental conditions, easy isolation of products without column chromatography and clean reaction profiles.

Microwave-assisted synthesis of (aminomethylene)bisphosphine oxides and (aminomethylene)bisphosphonates by a three-component condensation

A practical method was elaborated for the synthesis of (aminomethylene)bisphosphine oxides comprising the catalyst- and solvent-free microwave-assisted three-component condensation of primary amines, triethyl orthoformate and two equivalents of diphenylphosphine oxide. The method is also suitable for the preparation of (aminomethylene)bisphosphonates using (MeO)2P(O)H/(MeO)3CH or (EtO)2P(O)H/(EtO)3CH reactant pairs and even secondary amines. Several intermediates referring to the reaction mechanism together with a few by-products could also be identified.

A highly efficient and recyclable molybdate sulfuric acid (MSA) catalyst for the synthesis of dimethyl (2,3-dihydro-1H-inden-6-ylamino) (substituted) methylphosphonates under microwave irradiation

The attractive features of this methodology are simple procedure, green reaction, reusability and high efficiency of the catalyst and easy workability.

Ultrasound-Assisted One-Pot Synthesis of 1,3-Oxazine Derivatives Catalysed by BF3–SiO2 Under Neat Conditions

An efficient and environment-friendly method for the synthesis of 1,3-oxazine derivatives has been developed using the ultrasound-mediated condensation of 2-naphthol with formaldehyde and primary amines under solvent-free condition at room temperature in the presence of BF3-SiO2 to give the desired product in good to excellent yield. This procedure provides several advantages over current methods including a simple work-up, cost effectiveness, a reusable catalyst and shorter reaction times.