The development of environmentally benign and efficient synthetic protocols is still a central goal of current research in chemistry.1 Recently, heterogeneous multiphase reactions with gaseous reagents in closed microwave (MW) reactors stand out as key alternatives to conventional protocols.2 In this work the development of green and efficient procedures for alkynes semi-hydrogenations3 and aryl iodides aminocarbonylations,4 was efficiently accomplished under dielectric heating using solid recyclable catalysts, green solvents and H2 or CO mild pressure. MW-assisted semi-hydrogenation of 2-butyne-1,4-diol in flow mode was performed in ethanol over a novel Pd/Boehmite supported catalyst. The fast and selective conversion to 2-butene-1,4-diol (>85%) was obtained under H2 pressure (4.5 bar) (Fig. 1 A). Otherwise the safe use of CO in a pressure resistant MW reactor may create a technological breakthrough in carbonylation reactions. A new recyclable catalytic system CβCAT based on Pd(II)-triphenylphosphine embedded in cross-linked β-cyclodextrin (hexamethylene diisocyanate) has been found to be very efficient in aryl iodide aminocarbonylation reactions in the presence of nucleophilic amines. Several amide derivatives have been synthesized under MW irradiation in good to excellent yields (75-95%) under mild CO pressure (1.5 bar) at 125°C (Fig. 1 B). Both supported Pd catalysts showed competitive advantages, including easy recycle and negligible metal leaching also in flow-mode procedures. Several synthetic protocols may take advantage from MW-assisted heterogeneous gas-phase catalysis in term of environmental impact, efficiency and scalability.
XXXVII Convegno Nazionale della Divisione di Chimica Organica (Mestre, 18-22 Settembre 2016) [OC45] Microwave-Assisted Synthetic Protocols under Heterogeneous Gas-Phase Catalysis
CALCIO GAUDINO, Emanuela;ROTOLO, LAURA;BARGE, Alessandro;MARTINA, Katia;CRAVOTTO, Giancarlo
2016-01-01
Abstract
The development of environmentally benign and efficient synthetic protocols is still a central goal of current research in chemistry.1 Recently, heterogeneous multiphase reactions with gaseous reagents in closed microwave (MW) reactors stand out as key alternatives to conventional protocols.2 In this work the development of green and efficient procedures for alkynes semi-hydrogenations3 and aryl iodides aminocarbonylations,4 was efficiently accomplished under dielectric heating using solid recyclable catalysts, green solvents and H2 or CO mild pressure. MW-assisted semi-hydrogenation of 2-butyne-1,4-diol in flow mode was performed in ethanol over a novel Pd/Boehmite supported catalyst. The fast and selective conversion to 2-butene-1,4-diol (>85%) was obtained under H2 pressure (4.5 bar) (Fig. 1 A). Otherwise the safe use of CO in a pressure resistant MW reactor may create a technological breakthrough in carbonylation reactions. A new recyclable catalytic system CβCAT based on Pd(II)-triphenylphosphine embedded in cross-linked β-cyclodextrin (hexamethylene diisocyanate) has been found to be very efficient in aryl iodide aminocarbonylation reactions in the presence of nucleophilic amines. Several amide derivatives have been synthesized under MW irradiation in good to excellent yields (75-95%) under mild CO pressure (1.5 bar) at 125°C (Fig. 1 B). Both supported Pd catalysts showed competitive advantages, including easy recycle and negligible metal leaching also in flow-mode procedures. Several synthetic protocols may take advantage from MW-assisted heterogeneous gas-phase catalysis in term of environmental impact, efficiency and scalability.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
