8 research outputs found
Evaluating polymer-supported isothiourea catalysis in industrially-preferable solvents for the acylative kinetic resolution of secondary and tertiary heterocyclic alcohols in batch and flow
The authors thank the Royal Society and the Science and Engineering Board of India (SERB) for the award of a Royal Society-SERB Newton International Fellowship (N.R.G.). The authors also thank the EPSRC Centre for Doctoral Training in Critical Resource Catalysis (CRITICAT, grant code EP/L016419/1, R.M.N.P.) for funding. Financial support from the EPSRC (EP/K000411/1) is gratefully acknowledged (R.C.). The authors thank the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) ERC grant agreement no. 279850 (A.D.S). A.D.S. thanks the Royal Society for a Wolfson Research Merit Award. C.R.-E. and M.A.P. acknowledge the financial support from CERCA Programme/Generalitat de Catalunya, MINECO (CTQ2015-69136-R, AEI/MINECO/FEDER, UE and Severo Ochoa Excellence Accreditation 2014â2018, SEV-2013-0319) and DEC Generalitat de Catalunya (Grant 2014SGR827).Polymer-supported Lewis base catalysts, based on the homogeneous isothioureas HyperBTM and BTM, have been synthesised and applied for the acylative kinetic resolution of secondary and tertiary heterocyclic alcohols. In batch, the use of industrially-preferable solvents was investigated, with dimethyl carbonate proving to be most generally-applicable. Significantly, the HyperBTM-derived immobilised catalysts were readily recycled, with no loss in either activity or selectivity. In addition to the kinetic resolution of secondary benzylic, propargylic, allylic and cycloalkanol derivatives, a range of 21 tertiary heterocyclic alcohols, based on privileged 3-hydroxyoxindole and 3-hydroxypyrrolidinone substructures, were resolved with up to excellent selectivity (s = 7â190). Finally, the immobilised isothiourea catalysts were applied in a packed bed reactor to demonstrate the first example of the kinetic resolution of tertiary heterocyclic alcohols in a continuous flow process. High selectivities were obtained for the resolution of 3-hydroxyoxindole derivatives in ethyl acetate (s up to 70); and for 3-hydroxypyrrolidinones derivatives in toluene (s up to 42).PostprintPeer reviewe
Ligand-free solid supported palladium(0) nano/microparticles promoted CâO, CâS, and CâN cross coupling reaction
Ligand-free solid-supported nano and microparticles of Pd(0) (SS-Pd) were used as a heterogeneous catalyst
in carbon-heteroatom bond formation reactions. Nitro substituted aryl halides reacted with oxygen,
sulfur, and nitrogen nucleophiles to afford the corresponding products in good yields. A one-pot sequential
cross coupling and nitro-reduction was also performed using the same SS-Pd catalyst to access amine
substituted carbon-heteroatomic molecules. In addition, SS-Pd could be recycled up to seven runs without
a significant loss of catalytic activit
Solid supported Pd(0): an efficient recyclable heterogeneous catalyst for chemoselective reduction of nitroarenes
Solid supported palladium(0) (SS-Pd) catalyzed highly chemoselective reduction of nitroarenes to the
corresponding anilines was accomplished under a milder reaction condition. This catalyst showed high
compatibility with various reducing agents (NaBH4, Et3SiH, and NH2NH2âH2O) and a large number of
reducible functional groups such as sulfonamide, amides, carboxylic acid, ester, alcohol, halide, hetero
cycle, nitrile, alkene, carbonyl, O-benzyl, and N-benzyl were tolerated. Most of the reactions were clean
and high yielding. The SS-Pd catalyst could be recycled up to seven runs without significant loss of
activit
Solid supported palladium(0) nano/microparticle: a ligand-free efficient recyclable heterogeneous catalyst for mono- and b,b-double-Heck reaction
Solid supported palladium nano/microparticles were found to be active catalysts to perform mono- and
b,b-double-Heck reactions. Different b-unsubstituted and substituted alkenes including acrylate, methacrylate,
crotonate, styrene, acrylonitrile, and acrylamide were investigated successfully for mono- and b,
b-double-Heck reactions with aryl iodide under milder reaction condition. One-pot b,b-double-Heck
reaction of aryl iodides with a,b-unsaturated ester, amide, nitrile, and styrene derivatives were also
performed under standard reaction conditions. Wide functional group tolerance, easy catalyst recovery,
and recyclability up to twelve times without significant loss of catalytic activity added extra importance
to the present process
Solid-Supported Rhodium(0) Nano-/Microparticles: An Efficient Ligand-Free Heterogeneous Catalyst for Microwave-Assisted SuzukiâMiyaura Cross-Coupling Reaction
Solid-supported nano- and microparticles
of rhodium(0) (SS-Rh) were prepared and applied
as a ligand free heterogeneous catalyst for Suzukiâ
Miyaura cross-coupling reaction with wide range of
substrate scope. A hitherto unknown Rh-catalyzed
Suzuki cross-coupling reaction of aldehyde and cyanohaloarenes
was observed rather than the usual
nucleophilic arylation.The catalyst can be removed
by simple filtration and recycled upto twelve runs
without any deterioration of activity
Evaluating polymer-supported isothiourea catalysis in industrially-preferable solvents for the acylative kinetic resolution of secondary and tertiary heterocyclic alcohols in batch and flow
Polymer-supported Lewis base catalysts, based on the homogeneous isothioureas HyperBTM and BTM, have been synthesised and applied for the acylative kinetic resolution of secondary and tertiary heterocyclic alcohols. In batch, the use of industrially-preferable solvents was investigated, with dimethyl carbonate proving to be most generally-applicable. Significantly, the HyperBTM-derived immobilised catalysts were readily recycled, with no loss in either activity or selectivity. In addition to the kinetic resolution of secondary benzylic, propargylic, allylic and cycloalkanol derivatives, a range of 22 tertiary heterocyclic alcohols, based on privileged 3-hydroxyoxindole and 3-hydroxypyrrolidinone substructures, were resolved with up to excellent selectivity (s = 7â 190). Finally, the immobilised isothiourea catalysts were applied in a packed bed reactor to demonstrate the first example of the kinetic resolution of tertiary heterocyclic alcohols in a continuous flow process. High selectivities were obtained for the resolution of 3-hydroxyoxindole derivatives in ethyl acetate (s up to 70); and for 3-hydroxypyrrolidinones derivatives in toluene (s up to 42)