Lactic Acid: An Efficient and Green Catalyst for the One-Pot Five-Components Synthesis of Highly Substituted Piperidines

<p>Polyfunctionalized heterocyclic compounds have an important role in the drug discovery process and analysis of drugs in late development. Piperidines and their analogues have received attention owing to their biological activities, because of the importance of these heterocycle compounds, there is still a need to improve the ways for green synthesis of these compounds. In this study, lactic acid was applied as a green and efficient catalyst for the one-pot five-component synthesis of highly substituted piperidines from the reaction between aromatic aldehydes, aromatic amines, and b-ketoester at ambient temperature. This methodology has a number of advantages such as: use of easy access and green catalyst, short reaction times, high yields, and easy work-up (just simple filtration).</p

One-Pot, Sequential Four-Component Synthesis of Benzo[<i>a</i>]chromeno[2,3-<i>c</i>]phenazine Derivatives Using SiO₂–SO₃H as an Efficient and Recoverable Catalyst Under Conventional Heating and Microwave Irradiation

<p>Silica sulfuric acid (SiO₂–SO₃H) has been used as an effective and reusable solid catalyst for the one-pot, two-step, four-component microwave-assisted synthesis of benzo[a]chromeno[2,3-c]phenazine derivatives by the condensation reaction of 2-hydroxynaphthalene-1,4-dione, o-phenylenediamine, aldehydes, and cyclic 1,3-dicarbonyl compounds. This new procedure has a number of advantages such as: high yields, very short reaction time, operational simplicity, simple work-up procedures and avoidance of hazardous or toxic catalysts, and organic solvents and is devoid of inessential derivatization and generation of hazardous substances. Moreover, the catalyst shows high thermal stability and can be recovered and reused without loss of reactivity.</p

Synthesis of Functionalized γ-Spiroiminolactones through a One-Pot Three-Component Reaction of Isocyanides, Acetylenic Esters, and 6<i>H</i>-Indeno[1,2-<i>b</i>]pyrido[3,2-<i>e</i>]pyrazin-6-one

<p>A new and efficient isocyanide-based one-pot multi-component reaction has been described for the synthesis of novel ?-spiroiminolactone derivatives. Products were obtained by a three-component condensation reaction between isocyanides with acetylenic esters which was trapped with 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one (aromatic ketone) in CH2Cl2 without use of any catalyst or activator in excellent yields.</p