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Improving the efficiency of the Diels-Alder process by using flow chemistry and zeolite catalysis

• Improving the efficiency of the Diels-Alder process by using flow chemistry and zeolite catalysis
• Green Chem., 2017, Advance Article
  DOI: 10.1039/C6GC02334G, Paper

  S. Seghers, L. Protasova, S. Mullens, J. W. Thybaut, C. V. Stevens
  The industrial application of the Diels-Alder reaction for the synthesis of (hetero)cyclic compounds constitutes an important challenge. To tackle the reagent instability problems and corresponding safety issues, the use of a high-pressure and zeolite catalysed microreactor process is presented.

The industrial application of the Diels–Alder reaction for the atom-efficient synthesis of (hetero)cyclic compounds constitutes an important challenge. Safety and purity concerns, related to the instability of the polymerization prone diene and/or dienophile, limit the scalability of the production capacity of Diels–Alder products in a batch mode. To tackle these problems, the use of a high-pressure continuous microreactor process was considered. In order to increase the yields and the selectivity towards the endo-isomer, commercially available zeolites were used as a heterogeneous catalyst in a microscale packed bed reactor. As a result, a high conversion (≥95%) and endo-selectivity (89:11) were reached for the reaction of cyclopentadiene and methyl acrylate, using a 1:1 stoichiometry. A throughput of 0.87 g h⁻¹during at least 7 h was reached, corresponding to a 3.5 times higher catalytic productivity and a 14 times higher production of Diels–Alder adducts in comparison to the heterogeneous lab-scale batch process. Catalyst deactivation was hardly observed within this time frame. Moreover, complete regeneration of the zeolite was demonstrated using a straightforward calcination procedure

Improving the efficiency of the Diels–Alder process by using flow chemistry and zeolite catalysis

S. Seghers,^a   L. Protasova,^b   S. Mullens,^b  J. W. Thybaut^c and   C. V. Stevens*^a  

*

Corresponding authors

^a

SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
E-mail: chris.stevens@ugent.be

^b

VITO, Vlaamse Instelling voor Technologisch Onderzoek, Boeretang 200, 2400 Mol, Belgium

^c

Laboratory for Chemical Technology, Department of Chemical Engineering and Technical Chemistry, Faculty of Engineering and Architecture, Ghent University, Technologiepark 914, 9052 Ghent, Belgium

Green Chem., 2017, Advance Article

DOI: 10.1039/C6GC02334G
http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C6GC02334G?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

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Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C-H functionalization of pyridine N-oxides

Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C-H functionalization of pyridine N-oxides

Green Chem., 2016, Advance Article
DOI: 10.1039/C6GC02556K, Paper

Valentin A. Rassadin, Dmitry P. Zimin, Gulnara Z. Raskil'dina, Alexander Yu. Ivanov, Vadim P. Boyarskiy, Semen S. Zlotskii, Vadim Yu. Kukushkin
A solvent- and halide-free atom-economical synthesis of practically useful pyridine-2-yl substituted ureas utilizes pyridine N-oxides and dialkylcyanamides.

Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C–H functionalization of pyridine N-oxides

Valentin A. Rassadin,*^a   Dmitry P. Zimin,^a  Gulnara Z. Raskil'dina,^ab   Alexander Yu. Ivanov,^c  Vadim P. Boyarskiy,^a   Semen S. Zlotskii^b and  Vadim Yu. Kukushkin*^a  

*

Corresponding authors

^a

Institute of Chemistry, Saint Petersburg State University, Universitetskaya Nab. 7/9, 199034 Saint Petersburg, Russia
E-mail: v.rassadin@spbu.ru, v.kukushkin@spbu.ru

^b

Ufa State Petroleum Technological University, Kosmonavtov 1, Ufa, Bashkortostan, Russia

^c

Research Park SPbSU, Center for Magnetic Resonance, Saint Petersburg State University, Universitetskaya Nab. 7/9, 199034 Saint Petersburg, Russia

Green Chem., 2016, Advance Article

DOI: 10.1039/C6GC02556K

A novel solvent- and halide-free atom-economical synthesis of practically useful pyridine-2-yl substituted ureas utilizes easily accessible or commercially available pyridine N-oxides (PyO) and dialkylcyanamides. The observed C–H functionalization of PyO is suitable for the good-to-high yielding synthesis of a wide range of pyridine-2-yl substituted ureas featuring electron donating and electron withdrawing, sensitive, or even fugitive functional groups at any position of the pyridine ring (63–92%; 19 examples). In the cases of 3-substituted PyO, the C–H functionalization occurs regioselectively providing a route for facile generation of ureas bearing a 5-substituted pyridine-2-yl moiety.



1,1-Dimethyl-3-(pyridin-2-yl)urea

1,1-Dimethyl-3-(pyridin-2-yl)urea (4a)3 : From pyridine 1-oxide (1a) (95.0 mg, 1.00 mmol) and dimethylcyanamide (2a) (105 mg, 1.50 mmol), compound 4a (147 mg, 89%) was obtained according to GP1 as a yellow oil, which was then crystalized in the freezer to give pale yellow solid, m.p. = 42.6–43.5 °C, lit.4 m.p. = 44–47 °C (EtOAc/hexane), Rf = 0.25 (EtOAc). 1H NMR (400 MHz, CDCl3): δ = 3.00 (s, 6 H, NCH3), 6.88 (ddd, J = 7.3, 5.0, 0.9 Hz, 1 H), 7.30 (br. s, 1 H), 7.60 (ddd, J = 8.5, 7.3, 1.9 Hz, 1 H), 8.02 (dt, J = 8.5, 0.9 Hz, 1 H), 8.14 (ddd, J = 5.0, 1.9, 0.9 Hz, 1 H) ppm. 13C NMR (101 MHz, CDCl3): δ = 36.3 (2 С, CH3), 113.0 (CH), 118.1 (CH), 138.0 (CH), 147.3 (CH), 152.8 (C), 154.8 (C) ppm. NMR data are consistent with previously reported.3 HRMS (ESI), m/z: [M + H]+ calcd. for C8H12N3O+ : 166.0975; found: 166.0977.


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ENZYMES AS GREEN CATALYSTS FOR PHARMACEUTICAL INDUSTRY

ENZYMES AS GREEN CATALYSTS FOR PHARMACEUTICAL INDUSTRY
  'Green' Catalysts for 'greener' reactions - Dr. Dinesh Nair, Regional Business Manager at Novozymes South Asia Pvt. Ltd







 



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A high-yielding method for the preparation of isoxazolopyridin-3-amine derivatives

A highly efficient and green method has been developed for the rapid preparation of highly functionalized isoxazolopyridin-3-amine derivatives in excellent yields. This process has a broad substrate scope, is operationally simple, and generally requires no chromatographic purification. In addition, the process is scalable and significantly greener than current alternatives with a PMI of 18 and water as the reaction solvent.

A rapid preparation of highly functionalized isoxazolopyridin-3-amine and other heterocyclic fused aminoisoxazole derivatives

A high-yielding method for the preparation of isoxazolopyridin-3-amine derivatives

Wensheng Yu,*^a   Paul G. Bulger^b and   Kevin M. Maloney*^b  

*

Corresponding authors

^a

Discovery Chemistry, Merck Research Laboratories, 126 E. Lincoln Avenue, Rahway, USA
E-mail: wensheng.yu@merck.com

^b

Process Chemistry, Merck Research Laboratories, 126 E. Lincoln Avenue, Rahway, USA

Green Chem., 2016,18, 4941-4946

DOI: 10.1039/C6GC01125J

http://pubs.rsc.org/en/Content/ArticleLanding/2016/GC/C6GC01125J?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Wensheng Yu

Associate Principal Scientist at Merck

Paul G. Bulger was born in London, England, in 1978. He received his undergraduate M.Chem degree in 2000 from the University of Oxford, completing his Part II project under the supervision of Dr. Mark G. Moloney. He remained at Oxford for his graduate studies, obtaining his D. Phil. in chemistry in 2003 for research conducted under the supervision of Professor Sir Jack E. Baldwin. After an enjoyable three-year stint as a postdoctoral researcher in Professor K. C. Nicolaou's group at The Scripps Research Institute, he joined the Process Research Department of Merck & Co., Inc. in the fall of 2006.






pic not available

Kevin Maloney

Sr Research Chemist at Merck Sharp & Dohme

Experience

Sr Research Chemist

Merck Sharp & Dohme

Sr Research Chemist

Merck

2007 – Present (9 years)

Education

Massachusetts Institute of Technology

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A photoreactor that generates a thin film upon rotation for efficient irradiation of solutions is described. The reactor is based around a standard piece of equipment found in most synthetic laboratories, namely, a rotary evaporator. Three different photo-oxidation reactions have been used to examine the effects of several parameters such as irradiated volume, flask size, rotation speed, and light intensity. The reactor can be operated in a semicontinuous manner, and two possible configurations are described. The thickness of the generated film and the rate of mixing under different conditions have been examined using in situ electronic absorption spectroscopy.

Safety warning: Any experiment involving flammable organic solvents and air or pure oxygen is potentially hazardous, especially when partially contained, as is the case of the flask of our reactor. We took the following precautions and encountered no problems but we stress the need for readers to make safety assessments for their own experiments as peripheral circumstances may be different from ours. All experiments were carried out in a fume hood or ventilated enclosure with adequate ventilation and the front lowered. Any obvious sources of ignition were removed. Oxygen was fed from a cylinder fitted with a compliant regulator and was delivered at a maintained pressure of 1 bar using a mass flow controller compatible with oxygen. The equipment was maintained and cleaned free of grease at all times to prevent any incompatibilities with oxygen. Temperatures were kept at ambient. When working above the solvent flash point and LOC, care must be taken to ensure that all possible risks have been considered. Appropriate safeguards and suitable safety measures must be implemented.

A Simple and Versatile Reactor for Photochemistry

Charlotte A. Clark†, Darren S. Lee†, Stephen J. Pickering‡, Martyn Poliakoff*†, and Michael W. George*†§

†School of Chemistry, ‡Department of Mechanical, Materials and Manufacturing Engineering, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom

§ Department of Chemical and Environmental Engineering, The University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo 315100, China

Org. Process Res. Dev., Article ASAP

DOI: 10.1021/acs.oprd.6b00257

http://pubs.acs.org/doi/abs/10.1021/acs.oprd.6b00257

*E-mail: martyn.poliakoff@nottingham.ac.uk (M.P.)., *E-mail: mike.george@nottingham.ac.uk (M.W.G.).

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