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Friday, 23 June 2017

Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source


Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source
Green Chem., 2017, Advance Article
DOI: 10.1039/C7GC01289F, Paper
Zhanhui Yang, Zhongpeng Zhu, Renshi Luo, Xiang Qiu, Ji-tian Liu, Jing-Kui Yang, Weiping Tang
A highly efficient iridium catalyst is developed for the chemoselective reduction of aldehydes to alcohols in water, using formic acid as a reductant.

Green Chemistry

Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source

Abstract

A water-soluble highly efficient iridium catalyst is developed for the chemoselective reduction of aldehydes to alcohols in water. The reduction uses formic acid as the traceless reducing agent and water as a solvent. It can be carried out in air without the need for inert atmosphere protection. The products can be purified by simple extraction without any column chromatography. The catalyst loading can be as low as 0.005 mol% and the turn-over frequency (TOF) is as high as 73 800 mol mol−1 h−1. A wide variety of functional groups, such as electron-rich or deficient (hetero)arenes and alkenes, alkyloxy groups, halogens, phenols, ketones, esters, carboxylic acids, cyano, and nitro groups, are all well tolerated, indicating excellent chemoselectivity.
Image result for 4-Methoxybenzyl alcohol
4-Methoxybenzyl alcohol (2a)2 . Yellowish oil. Yield: 273 mg, 99%.
1H NMR (400 MHz, CDCl3) δ 7.23 (d, J = 8.8 Hz, 2H), 6.85 (d, J = 8.7 Hz, 2H), 4.52 (s, 2H), 3.76 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 159.07, 133.23, 128.63, 113.89, 64.73, 55.30, 55.26.

Zhanhui Yang

Zhanhui Yang

School of Pharmacy, University of Wisconsin–Madison, Madison, USA
E-mail:weiping.tang@wisc.edu

Organic Chemistry, Green Chemistry, Catalysis

PhD student
Beijing University of Chemical Technology
Organic Chemistry
Beijing, China
Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA
School of Pharmacy, University of Wisconsin–Madison, Madison, USA
Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA
Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA
Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA
4-Methoxybenzyl alcohol
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Thursday, 22 June 2017

CP 11



Image result for SYNTHESIS OF HNIWstr1
image file: c5nr07855e-s10.tif
 Scheme 10 Synthesis of C60-PGN and C60-GAP.
It has been calculated that the enthalpy of formation of Cp-5 is 2782.2 kJ mol−1, while its detonation velocity and pressure are 3282 km s−1 and 4.443 GPa, respectively.112 Upon complete combustion, the total heat of combustion for Cp-5 is 2.17 × 105 kJ mol−1 due to its high carbon content. It seems that this compound may not be useful as the main ingredient of an explosive or a propellant but it might be a good additive for heat-generating energetic compositions. To improve the energetic content of fullerene derivatives, more nitro groups can be introduced on the fullerene skeleton. Such a strategy has been recently attempted, where a high-nitrogen-content derivative, C60(NO2)14 (FP, CP-10), was prepared and characterized,113 using a prolonged treatment of C60 in benzene with very high concentrations of N2O4. However, Cp-10 is not so thermally stable and it deflagrates when heated above 170 °C in nitrogen or air, releasing a considerable amount of heat. This compound may be used as a powerful explosive, depending on its sensitivity, which has not been reported. In addition to the nitro-derivatives of fullerene, fullerene nitrates have also been reported that can be used in propellant compositions as energetic burn rate modifiers. As a typical example, fullerene ethylenediamine nitrate (Cp-11, FEDN) was synthesized by reacting fullerene and ethylenediamine in diluted nitric acid (Scheme ).114
  1. 112 B. Tan, R. Peng, H. Li, B. O. Jin, S. Chu and X. Long, Theoretical investigation of an energetic fullerene derivative, J. Comput. Chem., 2010, 31, 2233–2237 CAS.
  2. 113 F. Cataldo, O. Ursini and G. Angelini, Synthesis and explosive decomposition of polynitro[60]fullerene, Carbon, 2013, 62, 413–421 CrossRef CAS.
  3. 114 B.-L. Chen, B. Jin, R.-F. Peng, F.-Q. Zhao, J.-H. Yi, W.-J. Han, H.-J. Guan and S.-J. Chu, Synthesis and characterization of fullerene-ethylenediamine nitrate, Chin. J. Energet. Mater., 2014, 22, 186–191 CAS.
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Efficient and Stereoselective Syntheses of Isomerically Pure 4-Aminotetrahydro-2H-thiopyran 1-Oxide Derivatives

 

trans-4-Aminotetrahydro-2H-thiopyran 1-Oxide Methanesulfonate (trans-3d-MsOH)
Compound ...................afforded trans-3d-MsOH (20 g, 68%) as a white crystalline solid.
1H NMR (300 MHz, DMSO-d6) δ 1.60–1.76 (2H, m), 2.16–2.29 (2H, m), 2.31 (3H, s), 2.68–2.81 (2H, m), 3.13–3.23 (2H, m), 3.27–3.35 (1H, m), 7.86 (3H, brs).
 
13C NMR (75 MHz, D2O) δ 24.98, 38.51, 46.18, 46.84.
 
LCMS m/z calcd for C5H11NOS: 133.06, found 134.1 [M + H].
 
Anal. Calcd for C6H15NO4S2: C, 31.43; H, 6.59; N, 6.11. Found: C, 31.62; H, 6.48; N, 6.19. mp 214–216 °C.
 
cis-4-Aminotetrahydro-2H-thiopyran 1-Oxide Hydrochloride (cis-4d-HCl)
A mixture of .................... to afford cis-4d-HCl (22.5 g, 62%) as a white crystalline solid.
1H NMR (400 MHz, DMSO-d6) δ 1.81–2.00 (2H, m), 2.06–2.24 (2H, m), 2.73 (2H, td, J = 13.6, 3.2 Hz), 2.90–3.01 (2H, m), 3.21 (1H, brs), 8.19 (3H, brs).
 
13C NMR (75 MHz, D2O) δ 19.80, 42.94, 47.34.
 
LCMS m/z calcd for C5H11NOS: 133.06, found 134.1 [M + H]. Anal. Calcd for C5H12NClOS: C, 35.39; H, 7.13; N, 8.26. Found: C, 35.28; H, 6.87; N, 8.26. mp 230–232 °C.
 
Efficient and Stereoselective Syntheses of Isomerically Pure 4-Aminotetrahydro-2H-thiopyran 1-Oxide Derivatives
 Research, Takeda Pharmaceutical Company Ltd., Fujisawa, Kanagawa 251-8555, Japan
 Pharmaceutical Sciences, Takeda Pharmaceutical Company Ltd., Yodogawa-ku, Osaka 532-8686, Japan
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/acs.oprd.7b00147
 
*E-mail: ryo.mizojiri@takeda.com. Phone: +81-466-32-1058 (R.M.)., *E-mail: tetsuji.kawamoto@takeda.com. Phone: +81-466-32-1193 (T.K.).
Abstract Image
Efficient and stereoselective syntheses of isomerically pure 4-aminotetrahydro-2H-thiopyran 1-oxide derivatives have successfully been achieved. Isomerically pure (4-nitrophenyl)sulfonyltetrahydro-2H-thiopyran 1-oxides were identified by X-ray crystallographic analyses, and isomerically pure sulfoxide derivatives were characterized by 1H NMR. An oxidation reaction of tert-butyl(4-nitrophenyl)sulfonyl(tetrahydro-2H-thiopyran-4-yl)carbamate with Oxone provided steric control, affording its trans sulfoxide with high efficiency and selectivity. From the obtained trans sulfoxide derivatives, cis sulfoxide derivatives were synthesized conveniently by a hydrogen chloride catalyzed isomerization.

str1 str2

Tropylium salts as efficient organic Lewis acid catalysts for acetalization and transacetalization reactions in batch and flow

Green Chem., 2017, Advance Article
DOI: 10.1039/C7GC01519D, Communication
D. J. M. Lyons, R. D. Crocker, D. Enders, T. V. Nguyen
Tropylium salts were reported as organic-Lewis acids to efficiently catalyze acetalization reactions in batch and flow.

Tropylium salts as efficient organic Lewis acid catalysts for acetalization and transacetalization reactions in batch and flow

 

Abstract

Acetalization reactions play significant roles in the synthetically important masking chemistry of carbonyl compounds. Herein we demonstrate for the first time that tropylium salts can act as organic Lewis acid catalysts to facilitate acetalization and transacetalization reactions of a wide range of aldehyde substrates. This metal-free method works efficiently in both batch and flow conditions, prompting further future applications of tropylium organocatalysts in green synthesis.

1-(Diethoxymethyl)-4-methylbenzene (4a):
Prepared according to the general procedure from p-tolualdehyde and triethylorthoformate to yield the title compound as a colourless oil (99 mg, 0.50 mmol, quant. yield). 4a
1 H NMR (400 MHz, CDCl3) δ 7.38 (d, J = 8.1 Hz, 2H), 7.18 (d, J = 7.9 Hz, 2H), 5.50 (s, 1H), 3.59 (ddq, J = 35.4, 9.5, 7.1 Hz, 4H), 2.37 (s, 3H), 1.25 (t, J = 7.1 Hz, 6H) ppm;
13C NMR (101 MHz, CDCl3) δ 138.0, 136.3, 128.9, 126.64, 101.7, 61.0, 21.3, 15.3 ppm;
IR (KBr) 2973, 2880, 2327, 2102, 1909, 1740, 1448 cm-1 ;
ESI-MS Anal. Calcd. for 217.1199 C12H18O2Na, found 217.1195
1H NMR
1 H NMR (400 MHz, CDCl3) δ 7.38 (d, J = 8.1 Hz, 2H), 7.18 (d, J = 7.9 Hz, 2H), 5.50 (s, 1H), 3.59 (ddq, J = 35.4, 9.5, 7.1 Hz, 4H), 2.37 (s, 3H), 1.25 (t, J = 7.1 Hz, 6H) ppm;
13c nmr
13C NMR (101 MHz, CDCl3) δ 138.0, 136.3, 128.9, 126.64, 101.7, 61.0, 21.3, 15.3 ppm;
UNSW

Vinh Nguyen

Vinh Nguyen
BE (Hon 1, UNSW), Ph.D (ANU), MRACI CChem
Lecturer and DECRA fellow

Contact details

Phone: +61-2-9385 6167
Email: t.v.nguyen@unsw.edu.au

Office

Room 217 Dalton Building (F12)
School of Chemistry - UNSW
Research Group Website
 

Biographical Details

Dr. Vinh Nguyen (also known as: Thanh Vinh Nguyen or Thanh V. Nguyen on academic publication) was born in Vietnam. After high school, he went to Sydney, Australia to study industrial chemistry at University of New South Wales. He then moved to undertake his PhD in organic chemistry with Professor Michael Sherburn at the Australian National University, Canberra. He had worked to develop new synthetic methodologies for application in natural product synthesis and worked on the design and synthesis of enormoussynthetic host molecules for drug-delivery modelling. After graduating in 2010, he came to work on organocatalysis in Professor Dieter Enders group at the Institute of Organic Chemistry, RWTH Aachen, Germany under the auspices of an Alexander von Humboldt Postdoctoral Fellowship.  In June 2013, he moved to Curtin University (Perth, Australia) to start his own independent research group. In June 2015, he moved again to UNSW (Sydney) to take up a Lecturer/DECRA fellow position at the School of Chemistry. His current research interests are organocatalysis, aromatic cation activation, synthesis of naturally occurring and bioactive compounds, asymmetric synthesis and medicinal chemistry.
Selected Awards and Academic Achievements
  • 2016: The 2016 Athel Beckwith Lectureship from RACI Organic Chemistry Division
  • 2015-2018: ARC Discovery Early Career Researcher Award (DECRA)
  • 2014: Thieme Chemistry Journal Award for outstanding early career academics.
  • 2011 – 2013: Alexander von Humboldt Postdoctoral Fellowship (RWTH Aachen, Germany).
  • 2005: The Era Polymer Prize for “The Best Honor Research Thesis” in Industrial Chemistry – UNSW
  • 2000: Silver medal in the 32nd International Chemistry Olympiad in Copenhagen, Denmark

Research interests

Nguyen’s group focuses their research on development of new synthetic methodologies in organic chemistry, organocatalysis and natural product synthesis.
Aromatic Cation Activation:
A new method for the nucleophilic substitution of alcohols and carboxylic acids and other substrates using aromatic tropylium cation activation has been developed. It demonstrates, for the first time, the synthetic potential of tropylium cations in promoting chemical transformations. (http://pubs.acs.org/doi/abs/10.1021/ol5003972).

Tuesday, 20 June 2017

A Convenient and “Greener” Synthesis of Methyl Nitroacetate


Abstract Image
Methyl Nitroacetate (2)
Warning: Although no incidents occurred, the intermediates generated, as well as the end product, are energetic and should be handled as if they are explosive materials. It is essential that all reactions be conducted behind a blast shield and that proper protective equipment, including a face shield, be worn at all times during the operation.
A new procedure for the synthesis and isolation of methyl nitroacetate is described. The previously published method required drying the explosive dipotassium salt of nitroacetic acid in a vacuum desiccator, followed by grinding this material into a fine powder with a mortar and pestle prior to esterification. To obtain the desired product, benzene was employed as the extraction solvent, sodium sulfate was used as the drying agent, and two distillations were required. The new procedure eliminates drying and grinding of the explosive dipotassium salt, employs ethyl acetate or dichloromethane as the extraction solvent, eliminates the need for a drying agent, and requires a single distillation to furnish the end product in high yield and purity.
Figure
clear colorless liquid, bp 65 °C (3.9 Torr).
1H NMR (400 MHz; CDCl3) δ 5.18 (s, 2H), 3.87 (s, 3H);
13C NMR (100 MHz, CDCl3) δ 162.5, 76.2, 53.6;
IR (neat): 3041, 2967, 1751, 1557;
Tdec= 251 °C (onset), 272 °C (peak).
NMR PREDICT
Energetics Technology Branch, Energetic Materials Science Branch, U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/acs.oprd.7b00093
 
*E-mail: jesse.j.sabatini.civ@mail.mil. Phone: 410-278-0235., *E-mail: pablo.e.guzman2.civ@mail.mil. Phone: 410-278-8608.
 
NMR predict
str1 str2