Highly chemoselective reduction of nitroarenes over non-noble metal nickel-molybdenum oxide catalysts

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Highly chemoselective reduction of nitroarenes over non-noble metal nickel-molybdenum oxide catalysts

Green Chem., 2017, 19,809-815
DOI: 10.1039/C6GC03141B, Paper
Haigen Huang, Xueguang Wang, Xu Li, Chenju Chen, Xiujing Zou, Weizhong Ding, Xionggang Lu
A non-noble Ni-MoO3/CN@SBA-15 catalyst exhibits unprecedented catalytic activity and chemoselectivity for the reduction of nitroarenes to anilines in ethanol with hydrazine hydrate.

Highly chemoselective reduction of nitroarenes over non-noble metal nickel-molybdenum oxide catalysts

Haigen Huang,a  Xueguang Wang,*ab  Xu Li,a  Chenju Chen,b  Xiujing Zou,b  Weizhong Dingab and  Xionggang Lu*ab  
*Corresponding authors
aState Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072, China
E-mail: wxg228@shu.edu.cn, luxg@shu.edu.cn
bShanghai Key Laboratory of Advanced Ferrometallurgy, Shanghai University, China
Green Chem., 2017,19, 809-815

DOI: 10.1039/C6GC03141B

The chemoselective reduction of…

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Synthesis of tetrazines from gem-difluoroalkenes under aerobic conditions at room temperature

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Synthesis of tetrazines from gem-difluoroalkenes under aerobic conditions at room temperature

Green Chem., 2017, Advance Article
DOI: 10.1039/C6GC03494B, Paper
Zheng Fang, Wen-Li Hu, De-Yong Liu, Chu-Yi Yu, Xiang-Guo Hu
A procedure for the synthesis of tetrazines from gem-difluoroalkenes under aerobic conditions has been developed.

Synthesis of tetrazines from gem-difluoroalkenes under aerobic conditions at room temperature

Zheng Fang,a  Wen-Li Hu,a  De-Yong Liu,a  Chu-Yi Yuab and  Xiang-Guo Hu*a  
*Corresponding authors
aNational Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, P. R. China
E-mail: huxiangg@iccas.ac.cn
bBeijing National Laboratory for Molecular Science (BNLMS), CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
Green Chem., 2017, Advance Article

DOI: 10.1039/C6GC03494B, http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C6GC03494B?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

An efficient and green procedure for the synthesis of tetrazines has…

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Photobiocatalytic alcohol oxidation using LED light sources

Photobiocatalytic alcohol oxidation using LED light sources

Oxidative lactonization of meso-3-methyl-1,5-pentanediol to (S)-4-methyltetrahydro-2H-pyran-2-one using horse liver alcohol dehydrogenase (HLADH) and photocatalytic, aerobic regeneration of NAD+.

Green Chem., 2017, 19,376-379
DOI: 10.1039/C6GC02008A, Communication
Open Access Open Access
Creative Commons Licence  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
M. Rauch, S. Schmidt, I. W. C. E. Arends, K. Oppelt, S. Kara, F. Hollmann
The photocatalytic oxidation of NADH using a flavin photocatalyst and a simple blue LED light source is reported.

Photobiocatalytic alcohol oxidation using LED light sources

M. Rauch,a   S. Schmidt,a   I. W. C. E. Arends,a   K. Oppelt,b  S. Karac and   F. Hollmann*a  
*Corresponding authors
aDepartment of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629HZ Delft, The Netherlands
E-mail: f.hollmann@tudelft.nl
bInstitute of Inorganic Chemistry, Johannes Kepler University Linz, Altenberger Strasse 69, 4040 Linz, Austria
cInstitute of Technical Biocatalysis, Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
Green Chem., 2017,19, 376-379

DOI: 10.1039/C6GC02008A, http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C6GC02008A?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

image file: c6gc02008a-s1.tif
Scheme 1 Aerobic oxidation of reduced nicotinamide cofactors (NAD(P)H) to the corresponding cofactors (NAD(P)+) using photoexcited flavin catalysts. Upon photoexcitation (λ = 450 nm) the redox potential of the oxidised flavin catalyst increases dramatically enabling fast hydride transfer from NAD(P)H to the flavin. The reduced flavin reacts spontaneously in a dark reaction with molecular oxygen

The photocatalytic oxidation of NADH using a flavin photocatalyst and a simple blue LED light source is reported. This in situ NAD+ regeneration system can be used to promote biocatalytic, enantioselective oxidation reactions. Compared to the traditional use of white light bulbs this method enables very significant reductions in energy consumption and CO2 emission.

Synthesis of (S)-4-methyltetrahydro-2H-pyran-2-one catalyzed by HLADH The synthesis of (S)-4-methyltetrahydro-2H-pyran-2-one was performed as previously reported by Kara et al. (2013).[3] For this, a stock of meso-3-methyl-1,5-pentanediol (0.5 M), NAD+ stock (25 mM), acetosyringone stock (2 mM), and HLADH stock (3 gL–1 ) were freshly prepared in 50 mM Tris-HCl buffer at pH 8. The laccase was applied as delivered (0.2 mM solution). The mixture of meso-3- methyl-1,5-pentanediol stock (1 mL), acetosyringone stock (1 mL), NAD+ stock (0.2 mL) and buffer (6.7 mL) was incubated at 30 °C for 5 min. Finally, laccase (0.1 mL) and HLADH solution (1 mL) were added. The starting concentrations were: 50 mM meso-3-methyl-1,5-pentanediol, 0.5 mM NAD+ , 200 µM acetosyringone, 0.3 gL–1 HLADH and 2 µM laccase. The reaction mixture (10 mL) was orbitaly shaken at 600 rpm in 50 mL Falcon tubes at 30 °C. Samples (50 µL) were taken at defined time intervals and mixed with 200 µL EtOAc (containing 5 mM acetophenone). The mixture was vortexed and dried over anhydrous MgSO4. A conversion of 72 % to the enantiopure (S)-4-methyltetrahydro- 2H-pyran-2-one (ee > 99% according to GC analysis) was achieved after 16 hours. The reaction mixture (10 mL) was then saturated with NaCl and extracted with EtOAc (3 x 10 mL). After each extraction step the mixture was centrifuged (4000 rpm, 10 min). The collected clear organic phase was dried over anhydrous MgSO4 and the solvent was removed under reduced pressure to give a yellowish oily compound (39 mg). Purification of the crude product was attempted by column chromatography (Pasteur pipette filled with Silica gel 60, 70-230 mesh particle size; solvent petroleum ether: ethyl acetate 9:1).

. Picture of the reaction setup. Commercially available LED bands (3 colored) were wrapped around a thermostatted reaction vessel and used for illumination of the reaction mixture inside (S)-4-Me-DVL (R)-4-Me-DVL (generally in a Schlenk vessel) a slight overpressure was achieved by an air-filled balloon to reduce O2-transfer limitations to the reaction mixture

//////////Photobiocatalytic alcohol oxidation,  LED light sources

Asymmetric synthesis of (S)-phenylacetylcarbinol – closing a gap in C–C bond formation

Graphical abstract: Asymmetric synthesis of (S)-phenylacetylcarbinol – closing a gap in C–C bond formation

image file: c6gc01803c-f3.tif
Fig. 3 Stereoselectivities of the new ApPDC-variants for the synthesis of (S)-PAC. The different variants were tested as wet cells, crude cell extracts, and purified enzymes. Reaction conditions: wet cells – 20 mM benzaldehyde; 200 mM pyruvate; 50 mM KPi-buffer (pH 6.5), 2.5 mM MgSO4; 0.1 mM ThDP; 20 °C; 800 rpm, 800 μL reaction volume in 1.5 mL closed glass vials, whole cell catalyst concentration of 50 mg mL−1. Crude cell extract – 20 mM benzaldehyde; 200 mM pyruvate; 50 mM KPi-buffer (pH 6.5), 2.5 mM MgSO4; 0.1 mM ThDP; 20 °C; 800 rpm, 500 μL reaction volume in a 96-well sheet; see ESI chapter 2.1.4–2.1.5 for the catalyst concentration. Purified enzyme – 40 mM benzaldehyde; 200 mM pyruvate; 50 mM KPi-buffer with three different pH values, 2.5 mM MgSO4; 0.1 mM ThDP; 22 °C; 800 rpm, 800 μL reaction volume in 1.5 mL closed glass vials; protein concentration of 1 mg mL−1.

Asymmetric synthesis of (S)-phenylacetylcarbinol – closing a gap in C–C bond formation

*Corresponding authors
aInstitute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, Leo-Brandt-Str. 1, 52425 Jülich, Germany
E-mail: do.rother@fz-juelich.de
bHERBRAND PharmaChemicals GmbH, Brambachstr. 31, 77723 Gegenbach, Germany
cAlbaNova University Center, Royal Institute of Technology – School of Biotechnology, Roslagstull 21, Stockholm, Sweden
dInstitute of Pharmaceutical Sciences, Albert-Ludwigs-University Freiburg, Albertstrasse 25, 79104 Freiburg, Germany
eMerz Pharma GmbH & Co. KGaA, Am Pharmapark, D-06861 Dessau-Rosslau, Germany
fInstitute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
gTRUMPF GmbH+Co.KG, Ditzingen Johann-Maus-Straße 2, 71254 Ditzingen, Germany
hEnzymicals AG, Walther-Rathenau-Str 49a, 17489 Greifswald, Germany
Green Chem., 2017,19, 380-384

DOI: 10.1039/C6GC01803C

(S)-Phenylacetylcarbinol [(S)-PAC] and its derivatives are valuable intermediates for the synthesis of various active pharmaceutical ingredients (APIs), but their selective synthesis is challenging. As no highly selective enzymes or chemical catalysts were available, we used semi-rational enzyme engineering to tailor a potent biocatalyst to be >97% stereoselective for the synthesis of (S)-PAC. By optimizing the reaction and process used, industrially relevant product concentrations of >48 g L−1 (up to 320 mM) were achieved. In addition, the best enzyme variant gave access to a broad range of ring-substituted (S)-PAC derivatives with high stereoselectivity, especially for meta-substituted products.

image file: c6gc01803c-f2.tif
Fig. 2 Schematic representation of the active site of ApPDC. The legends explain the effect of different amino acid residues on the preferred orientation of the ThDP-bound donor substrate acetaldehyde, derived from pyruvate after decarboxylation (green rectangle) and the aromatic acceptor aldehyde (blue hexagon). The relative orientation of both substrates to each other defines the stereoselectivity of the product. (The figures refer to the stereoselectivities achieved with purified enzyme.)

///////////////Asymmetric synthesis, (S)-phenylacetylcarbinol,  C–C bond formation

http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C6GC01803C?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Pd/Cu-free Heck and Sonogashira cross-coupling reaction by Co nanoparticles immobilized on magnetic chitosan as reusable catalyst

ORGANIC CHEMISTRY SELECT

Pd/Cu-free Heck and Sonogashira cross-coupling reaction by Co nanoparticles immobilized on magnetic chitosan as reusable catalyst

Green Chem., 2017, Advance Article
DOI: 10.1039/C6GC03377F, Paper
Abdol R. Hajipour, Fatemeh Rezaei, Zahra Khorsandi
Chitosan (CS) is a porous, self-standing, nanofibrillar microsphere that can be used as a metal carrier. Amino groups on CS enable to modulate cobalt coordination using a safe organic ligand (methyl salicylate).

Pd/Cu-free Heck and Sonogashira cross-coupling reaction by Co nanoparticles immobilized on magnetic chitosan as reusable catalyst

aDepartment of Chemistry, Isfahan University of Technology, Isfahan 84156, Iran
E-mail: haji@cc.iut.ac.ir
Fax: +98 311 391 2350
Tel: +98 311 391 3262
bDepartment of Neuroscience, University of Wisconsin, Medical School, Madison, USA
Green Chem., 2017, Advance Article

DOI: 10.1039/C6GC03377F

Department of Chemistry
Office : College of Chemistry…

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Endogenous water-triggered and ultrasound accelerated synthesis of 1,5-disubstituted tetrazoles via a solvent and catalyst-free Ugi-azide reaction

ORGANIC CHEMISTRY SELECT

Endogenous water-triggered and ultrasound accelerated synthesis of 1,5-disubstituted tetrazoles via a solvent and catalyst-free Ugi-azide reaction

Green Chem., 2017, Advance Article
DOI: 10.1039/C6GC03324E, Communication
Shrikant G. Pharande, Alma Rosa Corrales Escobosa, Rocio Gamez-Montano
An ultrasound accelerated, environmentally benign Ugi-azide based method was developed for the synthesis of 1,5-disubstituted tetrazoles under solvent and catalyst-free conditions.

Endogenous water-triggered and ultrasound accelerated synthesis of 1,5-disubstituted tetrazoles via a solvent and catalyst-free Ugi-azide reaction

 *Corresponding authors
aDepartamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Noria Alta S/N, Col. Noria Alta, Guanajuato, México
E-mail: rociogm@ugto.mx
Green Chem., 2017, Advance Article

DOI: 10.1039/C6GC03324E,  http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C6GC03324E?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

A novel, sustainable, endogenous water-triggered, environmentally friendly, high substrate scope, efficient, solvent-free and catalyst-free Ugi-azide based method for the synthesis of 1,5-disubstituted tetrazoles is described.
N-((1-(tert-butyl)-1H-tetrazol-5-yl)(4-chlorophenyl)methyl)aniline…

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