New ruthenium(ii) catalysts enable the synthesis of 2-amino-4H-chromenes using primary alcohols via acceptorless dehydrogenative coupling

Abstract

A series of biologically important 2-amino-4H-chromenes functionalized with different substituents has been synthesized through one-pot multicomponent reaction catalysed by p-cymene Ru(II) organometallic complexes encompassing N˄O chelated carbazole based hydrazone ligands....

Harnessing alcohols as sustainable reagents for late-stage functionalisation: synthesis of drugs and bio-inspired compounds

“…161 Sharma and co-workers disclosed the palladium-catalysed coupling of unactivated alkenyl alcohols and olefin-tethered aryl halides (-Br and -I) for the synthesis of the drug probenecid 220a 0 , which is used for the treatment of gout and hyperuricemia (method Zze, Scheme 76). 162 As proposed, initially aryl halide 219a undergoes oxidative addition to Pd(II)-complex A followed by intermolecular carbopalladation, resulting in complex B. Next, the involvement of the C(sp 2 )-H bond of the pyridyl moiety with complex B transforms it into palladacycle complex C, which on protonolysis and 1,4 palladium shift affords complex D. Finally, complex D undergoes migratory insertion with olefin 218a followed by b-hydride elimination to give the desired product 220b.…”

Arene Binuclear Ru(II)-Promoted Sustainable Synthesis of Substituted Pyrazoles from Alcohols via Acceptorless Dehydrogenative Annulation

“…When the catalyst loading was lowered from 1 to 0.25 mol %, the yield of product 4a was reduced to 38% (0.5%) and later to 22% (0.25%) of the original yield (86%) (entries 19 and 20 in Table ). It is noteworthy that binuclear p -cymene Ru­(II) catalyst C2 showed superior reactivity to the previously reported mononuclear p -cymene Ru­(II) catalyst and Ru­(II) precursors (entries 21–23 in Table ). From the outcomes of the optimization reactions, the pertinent condition has been found as m -xylene/ t -BuOK at 140 °C for 18 h to explore the scope of 5-amino-4-cyano- N -aroylpyrazole products (Table ).…”