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

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.

An efficient and green procedure for the synthesis of tetrazines has been developed based on an old chemistry reported by Carboni in 1958. Both symmetric and asymmetric 3,6-disubstituted 1,2,4,5-tetrazines can be obtained in moderate to high yields from the corresponding gem-difluoroalkenes under aerobic conditions at room temperature. This work represents a rare example that ambient air is utilized as an oxidant for the synthesis of tetrazines.

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 Yu^ab and   Xiang-Guo Hu*^a  

Hide Affiliations

*

Corresponding authors

^a

National Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, P. R. China
 E-mail: huxiangg@iccas.ac.cn

^b

Beijing 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

3,6−bis([1,1'−biphenyl]−4−ylmethyl)−1,2,4,5−tetra zine (3a). (41 mg, 83%). purple solid;

m.p. 200−202°C;

IR(KBr) nmax/cm−1 2924, 2850, 1488, 1451, 1432, 1388, 851, 750;

1 H NMR (400 MHz, CDCl3) 7.55−7.33 (m, 18H), 4.65 (s, 4H).

 13C NMR (100 MHz, CDCl3) δ 169.2, 140.6, 140.4, 134.8, 129.7, 128.8, 127.6, 127.4, 127.1, 40.9;

HRMS (ESI): calcd. for C28H22N4 [M+H]+ 415.19172, found 415.19124.



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One-Pot Reductive Cyclisations of Nitroanilines to Imidazoles

Hana and co-workers ( Synlett 2010, 18, 2759−2764) from Genentech have developed a single-step procedure for conversion of 2-nitro aromatic amines to benzimidazoles. Addition of ammonium chloride proved necessary as Fe powder and formic acid alone was ineffective for nitro reduction. These conditions were compatible with a variety of functional groups on the aromatic, including boronate esters. The methodology was also extended to nitro aminopyridines but failed to deliver the desired product with isoxazole or pyrazole reactants.

Mild and General One-Pot Reduction and Cyclization of Aromatic and Heteroaromatic 2-Nitroamines to Bicyclic 2H-Imidazoles

Emily J. Hanan*, Bryan K. Chan, Anthony A. Estrada, Daniel G. Shore, Joseph P. Lyssikatos

*Discovery Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA, Email: hanan.emilygene.com

E. J. Hanan, B. K. Chan, A. A. Estrada, D. G. Shore, J. P. Lyssikatos, Synlett, 2010, 2759-2764.

DOI: 10.1055/s-0030-1259007

---

see article for more reactions

Abstract

A one-pot procedure for the conversion of aromatic and heteroaromatic 2-nitroamines into bicyclic 2H-benzimidazoles employs formic acid, iron powder, and NH₄Cl as additive to reduce the nitro group and effect the imidazole cyclization with high-yielding conversions generally within one to two hours. The compatibility with a wide range of functional groups demonstrates the general utility of this procedure.

see article for more examples

//////////One-Pot, Reductive Cyclisations,  Nitroanilines,  Imidazoles

 

“ALL FOR DRUGS” CATERS TO EDUCATION GLOBALLY, No commercial exploits are done or advertisements added by me. This article is a compilation for educational purposes only.

P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent

1-Bromo-4-fluoro-2-((2-iodobenzyl)oxy)benzene

1-Bromo-4-fluoro-2-((2-iodobenzyl)oxy)benzene

CAS 1161931-51-6

 

Mp 89.8–92.3 °C.

IR (neat, ATR): 3072 (w), 1482 (s), 1451 (s), 1294 (s), 1294 (s) cm^–1.

¹H NMR (399 MHz, DMSO-d₆) δ 5.12 (s, 2H), 6.81 (td, J = 8.49, 2.77 Hz, 1H), 7.14 (td, J = 7.64, 1.65 Hz, 1H), 7.18 (dd, J = 10.90, 2.82 Hz, 1H), 7.46 (td, J = 7.52, 0.92 Hz, 1H), 7.60 (dd, J = 7.64, 1.41 Hz, 1H), 7.62 (dd, J = 8.66, 6.23 Hz, 1H), 7.92 (dd, J = 7.83, 0.83 Hz, 1H).

¹³C NMR (100 MHz, DMSO-d₆) δ 74.5, 99.2, 102.4 (d, J = 27.1 Hz), 105.8 (d, J = 3.4 Hz), 108.9 (d, J = 22.5 Hz), 128.5, 129.8, 130.3, 133.6 (d, J = 9.9 Hz), 138.0, 139.2, 155.4 (d, J = 10.7 Hz), 162.2 (d, J = 244.3 Hz).

GCMS: m/z [M]⁺ calcd for C₁₃H₉BrFIO: 405.88600; found: 405.88620.

1H AND 13C NMR PREDICT

   

Org. Process Res. Dev., Article ASAP

DOI: 10.1021/acs.oprd.6b00368

 

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Brc2ccc(F)cc2OCc1ccccc1I

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, 19,237-248
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.

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., 2017,19, 237-248

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


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.







//////Diels-Alder,  flow chemistry, zeolite catalysis

Copper-catalyzed S-methylation of sulfonyl hydrazides with TBHP for the synthesis of methyl sulfones in water

Copper-catalyzed S-methylation of sulfonyl hydrazides with TBHP for the synthesis of methyl sulfones in water

Green Chem., 2017, 19,112-116
DOI: 10.1039/C6GC03142K, Communication

Yu Yang, Yajie Bao, Qianqian Guan, Qi Sun, Zhenggen Zha, Zhiyong Wang
A copper-catalyzed S-methylation of sulfonyl hydrazides with TBHP for the synthesis of methyl sulfones in water.

A copper-catalyzed S-methylation of sulfonyl hydrazides with TBHP was efficiently developed, providing a variety of methyl sulfones with good to excellent yields. The reaction can be carried out in water smoothly without any ligand or additive under mild conditions and this catalyst-in-water can be recycled several times.

Copper-catalyzed S-methylation of sulfonyl hydrazides with TBHP for the synthesis of methyl sulfones in water

Yu Yang,^a   Yajie Bao,^a   Qianqian Guan,^a   Qi Sun,^a  Zhenggen Zha^a and   Zhiyong Wang*^a  

*

Corresponding authors

^a

Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Soft Matter Chemistry and Department of Chemistry & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, P. R. China
 E-mail: zwang3@ustc.edu.cn
Fax: (+86) 551-360-3185

Green Chem., 2017,19, 112-116

DOI: 10.1039/C6GC03142K

General procedures for the synthesis of Arylsulfonyl Hydrazides Arylsulfonyl hydrazides 2b-2s were prepared according to the literature procedure.[1] To a solution of an arylsulfonyl chloride (3.0 mmol) in tetrahyrdofuran (15 mL), was added hydrazine monohydrate (375 mg, 7.5 mmol) dropwise under nitrogen at 0 °C. After vigorous stirring for 30 min at 0 °C, the reaction mixture was added ethyl acetate (60 mL), and washed with saturated brine (3 x 10 mL). The organic layer was dried over sodium sulfate, filtered, concentrated and added to hexane (12 mL) over 5 min. The mixture was filtered, and the collected solid was dried in vacuum.


1-methyl-4-(methylsulfonyl)benzene (3aa).[1] The title compound was prepared according to the general procedure and purified by column chromatography (Petroleum Ether: EtOAc = 3:1) to give a white solid (88 % yield).

1H NMR (400 MHz, CDCl3): 7.84-7.82 (d, 2H, J = 8.0 Hz), 7.38- 7.36 (d, 2H, J = 8.0 Hz ), 3.04 (s, 3H), 2.46 ( s, 3H );

13C NMR (100 MHz, CDCl3): 144.7, 137.7, 130.0, 127.3, 44.6, 21.6

Reference [1] G. Yuan, J. Zheng, X. Gao, X. Li, L. Huang, H. Chen and H. Jiang, Chem. Commun., 2012, 48, 7513.

1H NMR (400 MHz, CDCl3): 7.84-7.82 (d, 2H, J = 8.0 Hz), 7.38- 7.36 (d, 2H, J = 8.0 Hz ), 3.04 (s, 3H), 2.46 ( s, 3H );

13C NMR (100 MHz, CDCl3): 144.7, 137.7, 130.0, 127.3, 44.6, 21.6

• Formula: C₈H₁₀O₂S
• Molecular weight: 170.229
• CAS Registry Number: 3185-99-7
• Chemical structure: 
  

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Acid Chloride Negishi Couplings

With the plethora of new and efficient C–C bond-forming reactions available to the organic chemists growing on a monthly basis, one area that suffers is the substrate scope for previously reported examples. In this case Kim and Reike ( Tetrahedron Lett. 2011, 52, 1523−1526) reinvestigate work originally reported by Rovis. Initially Kim performs a small catalyst screen using various commercially available catalysts, resulting in Ni(acac)₂ being chosen for the remaining coupling reactions due to the rate of reaction and the isolated yield it facilitated. With a large selection of organozinc reagents via direct insertion developed by Reike, they then apply the developed conditions to 26 examples, all of which gave isolated product in good to excellent yields on gram scale.

Preparation of aryl ketones via Ni-catalyzed Negishi-coupling reactions with acid chlorides

• Seung-Hoi Kim^{a, ,} ,
• Reuben D. Rieke^b

• ^a Department of Chemistry, Dankook University, 29 Anseo, Cheonan 330-714, Republic of Korea
• ^b Rieke Metals, Inc., 1001 Kingbird Rd. Lincoln, NE 68521, USA
• http://www.sciencedirect.com/science/article/pii/S0040403911001845

Abstract

A Ni-catalyst-catalyzed cross-coupling reaction of organozinc reagents with acid chlorides has been successfully developed. Mild reaction conditions were required to complete the coupling reactions affording the corresponding aryl ketones in good to excellent yields.

---

Graphical abstract

 

A representative procedure of coupling reaction; In a 25 mL round-bottomed flask, Ni(acac)2, (0.06 g, 2 mol%) and 10 mL (5 mmol) of 0.5 M solution of 2- (ehtoxycarbonyl)phenylzinc bromide in THF was added into the flask at room temperature. Next, 6-chloronicotinoyl chloride (0.70 g, 4 mmol) dissolved in 5.0 mL of THF was added. The resulting mixture was refluxed overnight, then cooled down to room temperature. Quenched with saturated NH4Cl solution, then extracted with ethyl acetate (30 mL 3). Combined organics were washed with saturated Na2S2O3 solution and brine. Dried over anhydrous MgSO4. A flash column chromatography (50% EtOAc/50% Heptane) gave 0.78 g of 3g as yellow solid in 68% isolated.
Mp = 48–51 C. 1
H NMR (CDCl3, 500 MHz): d 8.59 (s, 1H), 8.11 (d, 2H, J = 10 Hz), 7.69 (t, 1H, J = 5 Hz), 7.62 (t, 1H, J = 5 Hz), 7.43 (d, 1H, J = 5 Hz), 7.38 (d, 1H, J = 10 Hz), 4.17 (q, 2H, J = 5 10 Hz), 1.19 (t, 3H, J = 10 Hz);
13C NMR (CDCl3, 125 MHz): d 194.8, 165.6, 155.6, 151.2, 140.6, 138.8, 133.0, 131.9, 130.6, 130.4, 129.2, 127.5, 124.6, 61.9, 14.0.
1H AND 13C NMR PREDICT

 

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O=C(c1cnc(Cl)cc1)c2ccccc2C(=O)OCC

Over the last 20 years organic carbamates have found numerous applications in pesticides, fungicides, herbicides, dyes, pharmaceuticals, cosmetics, and as protecting groups and intermediates for polyurethane synthesis. Recently, in order to avoid phosgene-based synthesis of carbamates, many environmentally benign and alternative pathways have been investigated. However, few examples of carbamoylation of aniline in continuous-flow apparatus have been reported. In this work, we report a high-yielding, dimethyl carbonate (DMC)-mediated carbamoylation of aniline in a fixed-bed continuously fed reactor employing basic zinc carbonate as catalyst. Several variables of the system have been investigated (i.e. molar ratio of reagents , flow rate, and reaction temperature) to optimize the operating conditions of the system.

Highly Selective Phosgene-Free Carbamoylation of Aniline by Dimethyl Carbonate under Continuous-Flow Conditions

Sandra Grego, Fabio Aricò, and Pietro Tundo*

Department of Environmental Sciences, Informatics and Statistics, Ca’ Foscari University of Venice, Dorsoduro 2137, 30123 Venezia, Italia

Org. Process Res. Dev., 2013, 17 (4), pp 679–683

DOI: 10.1021/op4000048, http://pubs.acs.org/doi/abs/10.1021/op4000048

*Tel.: (+39) 041 234 8642. Fax: (+39) 041 234 8620. E-mail: tundop@unive.it.

 

PIETRO TUNDO

Profile:

PIETRO R. TUNDO is Professor of Organic Chemistry at Ca’ Foscari University of Venice (Italy). 
He was guest researcher and teacher at College Station (Texas,1979-1981), Potsdam (New York, 1989-90) and Syracuse (New York, 1991-92), Chapel Hill, (North Carolina, 1995). 
He is Member of the Bureau of IUPAC.

P: Tundo is author of about 300 scientific publications, 40 patents and many books. 
His scientific interests are in the field of organic synthesis in selective methylations with low environmental impact, continuous flow chemistry, chemical detoxification of contaminants, hydrodehalogenation under multiphase conditions, phase-transfer catalysis (gas-liquid phase-transfer catalysis, GL-PTC), synthesis of crown-ethers and functionalized cryptands, supramolecular chemistry, heteropolyacids, and finally safe alternatives to harmful chemicals. 
He is the sole author of the book “Continuous flow methods in organic synthesis” E. Horwood Pub., Chichester, UK, 1991 (378 pp.), and editor of about 15 books.

P. Tundo was President of Organic and Biomolecular Chemistry Division of IUPAC (biennium 2007-2009) and holder of the Unesco Chair on Green Chemistry (UNTWIN N.o 731). He founded and was Chairman (2004-2016) of the Working Party on “Green and Sustainable Chemistry” of Euchems (European Association for Chemical and Molecular Sciences).
Founder of the IUPAC International Conferences Series on Green Chemistry, he was awarded by American Chemical Society on 1983 (Kendall Award, with Janos Fendler), and by Federchimica (Italian association of chemical industries) on 1997 (An Intelligent Future).
P. Tundo coordinated many institutional and industrial research projects (EU, NATO, Dow, ICI, Roquette) and was Director of the 10 editions of the annual Summer School on Green Chemistry (Venezia, Italy) sponsored by the EU, UNESCO and NATO.
He was guest researcher and teacher at College Station (Texas,1979-1981), Potsdam (New York, 1989-90) and Syracuse (New York, 1991-92), Chapel Hill, (North Carolina, 1995).
He is holder of the Unesco Chair on Green Chemistry (UNTWIN N.o 731) and author of about 260 scientific publications and 30 patents.
Scientific interests are in the field of organic synthesis in selective methylations with low environmental impact, continuous flow chemistry, chemical detoxification of contaminants, hydrodehalogenation under multiphase conditions, phase-transfer catalysis (gas-liquid phase-transfer catalysis, GL-PTC), synthesis of crown-ethers and functionalized cryptands, supramolecular chemistry and finally, heteropolyacids.
He is the sole author of the book "Continuous flow methods in organic synthesis" E. Horwood Pub., Chichester, UK, 1991 (378 pp.), and editor of about 15 books.
P. Tundo was President of Organic and Biomolecular Chemistry Division of IUPAC (biennium 2007-2009) and presently is Chairman of Working Party of "Green and Sustainable Chemistry" of Euchems (European Association for Chemical and Molecular Sciences).
Founder of the IUPAC International Conferences Series on Green Chemistry, he was awarded by American Chemical Society on 1983 (Kendall Award, with Janos Fendler), and by Federchimica (Italian association of chemical industries) on 1997 (An Intelligent Future).
P. Tundo co-ordinated many institutional and industrial research projects (EU, NATO, Dow, ICI, Roquette) and was Director of the 10 editions of the annual Summer School on Green Chemistry (Venezia), the latter sponsored by the EU, UNESCO and NATO.

Contact:

Professor of Organic Chemistry
Ca’ Foscari University of Venice
IUPAC Bureau Member
Tel. +39 041 2348642
Mob. +39 349 3486191
E-mail: tundop@unive.it

Phone	041 234 8642 / Lab .: 041 234 8669
E-mail	tundop@unive.it  green.chemistry@unive.it - 6th IUPAC Conference on Green Chemistry unescochair@unive.it - TUNDO Pietro
Fax	041 234 8620
Web	www.unive.it/persone/tundop

Pietro Tundo

////////Carbamoylation of Aniline, Dimethyl Carbonate, Continuous-Flow Conditions, flow synthesis

“ALL FOR DRUGS” CATERS TO EDUCATION GLOBALLY, No commercial exploits are done or advertisements added by me. This article is a compilation for educational purposes only.

P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent

Rhodium-catalyzed regiospecific C-H ortho-phenylation of benzoic acids with Cu/air as an oxidant

Rhodium-catalyzed regiospecific C-H ortho-phenylation of benzoic acids with Cu/air as an oxidant

Org. Chem. Front., 2017, Advance Article
DOI: 10.1039/C6QO00663A, Research Article

Shiguang Li, Guo-Jun Deng, Feifei Yin, Chao-Jun Li, Hang Gong
An efficient and practical synthetic approach for the regiospecific C-H ortho-phenylation of aromatic carboxylic acids in the absence of silver.

Rhodium-catalyzed regiospecific C–H ortho-phenylation of benzoic acids with Cu/air as an oxidant

Shiguang Li,^a   Guo-Jun Deng,^a   Feifei Yin,^a  Chao-Jun Li*^b and   Hang Gong*^a  *

Corresponding authors

^a

The Key Laboratory of Environmentally Friendly Chemistry and Application of the Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China
 E-mail: hgong@xtu.edu.cn

^b

Department of Chemistry and FQRNT Centre for Green Chemistry and Catalysis, McGill University, 801 Sherbrooke St. W., Montreal, Canada
 E-mail: cj.li@mcgill.ca

Org. Chem. Front., 2017, Advance Article

DOI: 10.1039/C6QO00663A

http://pubs.rsc.org/en/Content/ArticleLanding/2017/QO/C6QO00663A#!divAbstract

The development of an efficient and practical synthetic approach for the regiospecific C–H ortho-phenylation of aromatic carboxylic acids without the use of silver or costly coupling partners is reported. The rhodium-catalyzed C–H phenylation proceeded in the presence of Cu/air as a terminal oxidant. In most cases, numerous inactivated benzoic acids could couple with low-cost NaBPh₄ to obtain good to excellent yields.

A solution of aromatic acid 1a (27.2 mg, 0.2 mmol), NaBPh4 (0.27 g, 0.8 mmol), KF (46 mg, 0.8 mmol), [Rh(nbd)Cl]2 (9.2 mg, 0.02 mmol) and CuBr2 (4.5 mg, 0.02 mmol) in chlorobenzene (1.2 mL) was stirred in a sealed tube under air at 150 oC for 24 h. The reaction mixture was then cooled to room temperature and acidified by dilute aqueous HCl to pH<3, and then the solvent was evaporated in vacuo. The residue was purified by preparative thin-layer chromatography (TLC) on silica gel with petroleum ether and ethyl acetate as eluent to give the pure product 2a.

2a White solid; Yield 86%; Mp 132-134 oC [lit1 mp 133-135oC]; IR (neat) νmax 3057, 2917, 2849, 2627, 1682, 1461, 1133, 1064, 1000, 759, 696 cm-1; 1H NMR (400 MHz, CDCl3): δ = 7.35-7.40 (m, 6H), 7.23 (m, 2H), 2.45 (s, 3H); 13C NMR (100 MHz, CDCl3) δ = 174.5, 140.7, 140.2, 135.5, 132.2, 129.7, 129.2, 128.4 (2C), 127.6, 127.5, 20.0; HRMS (ESI) m/z calcd for C14H13O2 213.0910, found [M+H] + 213.0912.

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