Microwave-Assisted Green Catalytic Techniques: A Phosphine-Free Heck Reactive, One-Pot Amide Formation, And A Sustainable Preparation Of 2h-Indazoles 2,1-B Phthalazinetriones

In many fields, including industry, engineering, and medicine, amides play a crucial role as synthetic raw materials. An elegant functional embellishment with well-heeled chemistry, the amide group is present in a wide variety of bioactive compounds. An appealing field has been the development of sustainable and efficient technologies for amide synthesis. Since synthetic chemists are now interested in transition metal-mediated organic transformations, this study aims to identify transition metal catalysts that may have industrial and environmental applications. This paper offers a detailed exploration of the development of the green and efficient catalytic systems based on the forming of the carbon–carbon and carbon–nitrogen bonds by using the carbon-carbon and carbon-nitrogen transition-metal-mediated catalytic techniques. An unprecedented phosphine-free palladium complex, Pd(L)-Proline 2 was prepared and used as a recyclable and water-soluble catalyst in Heck coupling reactions under aqueous conditions with the assistance of microwave. The identical environmentally friendly methodology was applied in the preparation of the primary amides by the one-pot reaction of aldehydes with hydroxylamine hydrochloride catalyzed by Sc (OTf)3 and also to the preparation of the 2H-indazolo2,1-b phthalazinetrione derivatives by the use of KHSO4 SiO2 as a solid acid catalyst in solvent-free conditions. All the reactions were carried out at low intensity of the microwave irradiation with high yields (78-95) and short reaction times (10-50 min). The catalyst was very air and moisture stable and its application in solvent (water) complies with the concepts of green chemistry. IR, ¹H NMR, and ¹³C NMR spectroscopy were used to confirm that the synthesized products were structurally explained.