Palladium (0) Nanoparticles: A Novel and Reusable Catalyst for the Synthesis of Various Pyran Derivatives

Abstract

A ligand free, Palladium nanoparticles catalyzed synthesis of pyran derivatives using C-H activated compound, malononitrile and aryl aldehyde via Knoevenagel condensation followed by Michael addition reaction using Palladium nanoparticles as catalyst in one-pot is described herein. The advantages of this method lie in its simplicity, low catalyst loading, cost effectiveness and easy to handle. The Palladium Nanoparticles can be reused without loss of activity even after recycling four times. The palladium nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM). The present method also allows us to synthesize highly functionalized title compounds from simple and readily available inputs.

A new role for concentrated solar radiation (CSR) as a renewable heat source for the catalyst-solvent free synthesis of tetrahydrobenzo[b]pyran scaffolds

“…CaHPO 4 16 , SiO 2 NPs 17 , ethylenediamine diacetate 18 , SBPPSP 19 , I 2 20 , NH 4 Al(SO 4 ) 2 ·12H 2 O 21 , NH 4 H 2 PO 4 /Al 2 O 3 22 , ACoPc–MNPs 23 , ZnONPs 24 , Fe 3 O 4 @SiO 2 –imid–PMA 25 , NiFe 2 O 4 @SiO 2 –H 3 PW 12 O 40 26 , theophylline 27 , triethanolamine 28 , NaN 3 29 , Fe 3 O 4 @SiO 2 @TiO 2 30 , MgFe 2 O 4 nanoparticles 31 , trichloroisocyanuric acid 32 , Na 2 eosin Y 33 , DABCO 34 , Pd nanoparticles 35 , WELPSA 36 , Core/Shell CaO@SiO 2 –SO 3 H 37 , Co 3 O 4 nano-flakes 38 , HMS/Pr–Rh–Zr 39 , nano-SiO 2 /DBN 40 , M–Fe 3 O 4 @HAL–SO 3 H 41 , Bead-PIL 42 . It's worth noting that the Knoevenagel–Michael cyclocondensation reaction is a well-known method for producing tetrahydrobenzo[ b ]pyran scaffolds with either transition metal catalysts or organic solvents and/or conventional heating sources.…”

Methylene Blue as a Photo-Redox Catalyst: The Development Synthesis of Tetrahydrobenzo[b]pyran Scaffolds via a Single-Electron Transfer/Energy Transfer

“…Several methods for synthesizing tetrahydrobenzo[ b ]pyran scaffolds with MCRs in the presence of various catalysts have been published. For example, CaHPO 4 ( Bodaghifard et al, 2016 ), SiO 2 NPs ( Banerjee et al, 2011 ), ethylenediamine diacetate ( Zhou et al, 2017 ), silica-bonded N-propylpiperazine sodium n-propionate ( Niknam et al, 2013 ), I 2 ( Bhosale et al, 2007 ), NH 4 Al(SO 4 ) 2 .12H 2 O ( Mohammadi et al, 2017 ), NH 4 H 2 PO 4 /Al 2 O 3 ( Maleki and Sedigh Ashrafi, 2014 ), ACoPc-MNPs ( Zolfigol et al, 2016 ), ZnO NPs ( Banerjee and Saha, 2013 ), Fe 3 O 4 @SiO 2 -imid-PMA ( Esmaeilpour et al, 2015 ), NiFe 2 O 4 @SiO 2 –H 3 PW 12 O 40 ( Maleki et al, 2016 ), theophylline ( Mohamadpour, 2021c ), triethanolamine ( Rahnamaf et al, 2020 ), sodium alginate ( Mohamadpour, 2022a ), Fe 3 O 4 @SiO 2 @TiO 2 ( Khazaei et al, 2015 ), MgFe 2 O 4 nanoparticles ( Eshtehardian et al, 2020 ), trichloroisocyanuric acid ( Hojati et al, 2018 ), Na2 eosin Y ( Mohamadpour, 2021d ), DABCO ( Tahmassebi et al, 2011 ), and Pd nanoparticles ( Saha and Pal, 2012 ). There are limitations on metal catalysts such as, expensive reagents, severe reaction conditions, monotonous yields, environmental hazards, workup processes, and long reaction times associated with these methods.…”

Covalently anchored n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride on SBA-15 as a basic nanocatalyst for the synthesis of pyran heterocyclic compounds

“…Additionally the main drawback of almost existing methods is that the catalysts are decomposed under aqueous work-up conditions and their recoveries are oen impossible. 17 Thus, to overcome these drawbacks the development of simple and highly efficient methodologies remains desired.…”