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Showing posts with label nmr. Show all posts
Showing posts with label nmr. Show all posts

Tuesday 16 January 2018

Utilization of fluoroform for difluoromethylation in continuous flow: a concise synthesis of α-difluoromethyl-amino acids

 

Green Chem., 2018, 20,108-112
DOI: 10.1039/C7GC02913F, Communication
Open Access Open Access
Creative Commons Licence  This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Manuel Kockinger, Tanja Ciaglia, Michael Bersier, Paul Hanselmann, Bernhard Gutmann, C. Oliver Kappe
Difluoromethylated esters, malonates and amino acids (including the drug eflornithine) are obtained by a gas-liquid continuous flow protocol employing the abundant waste product fluoroform as an atom-efficient reagent.

Utilization of fluoroform for difluoromethylation in continuous flow: a concise synthesis of α-difluoromethyl-amino acids

 
Author affiliations

Abstract

Fluoroform (CHF3) can be considered as an ideal reagent for difluoromethylation reactions. However, due to the low reactivity of fluoroform, only very few applications have been reported so far. Herein we report a continuous flow difluoromethylation protocol on sp3 carbons employing fluoroform as a reagent. The protocol is applicable for the direct Cα-difluoromethylation of protected α-amino acids, and enables a highly atom efficient synthesis of the active pharmaceutical ingredient eflornithine.
Methyl 3,3-(difluoro)-2,2-diphenylpropanoate (2a) The product mixtures were collected and the solvent removed in vacuo. The products were isolated by thin layer chromatography (dichloromethane/hexane = 3/2 (v/v)). Yield: 173 mg (0.62 mmol, 62%); 93% by 19F NMR ;light yellow viscous liquid. 1 H NMR (300 MHz, D2O): δ = 7.45 – 7.19 (m, 10H), 6.90 (t, 2 JHF = 55.0 Hz, 1H), 3.79 (s, 3H). 13C NMR (75 MHz, D2O): δ = 171.1, 136.3, 129.8, 128.3, 128.2, 115.6 (t, 1 JCF = 246.2 Hz), 64.7, 53.1.19F NMR (282 MHz, D2O):δ = -123.0 (d, 2 JHF = 55.0 Hz).
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Conclusions

A gas–liquid continuous flow difluoromethylation protocol employing fluoroform as a reagent was reported. Fluoroform, a by-product of Teflon manufacture with little current synthetic value, is the most attractive reagent for difluoromethylation reactions. The continuous flow process allows this reaction to be performed within reaction times of 20 min with 2 equiv. of base and 3 equiv. of fluoroform. Importantly, the protocol allows the direct Cα-difluoromethylation of protected α-amino acids. These compounds are highly selective and potent inhibitors of pyridoxal phosphate-dependent decarboxylases. The starting materials are conveniently derived from the commercially available α-amino acid methyl esters, and the final products are obtained in excellent purities and yields after simple hydrolysis and precipitation. The developed process appears to be especially appealing for industrial applications, where atom economy, sustainability, reagent cost and reagent availability are important factors.
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Friday 12 January 2018

Bio-derived production of cinnamyl alcohol via a three step biocatalytic cascade and metabolic engineering

 

Green Chem., 2018, Advance Article
DOI: 10.1039/C7GC03325G, Paper
Evaldas Klumbys, Ziga Zebec, Nicholas J. Weise, Nicholas J. Turner, Nigel S. Scrutton
Cascade biocatalysis and metabolic engineering provide routes to cinnamyl alcohol.

Bio-derived production of cinnamyl alcohol via a three step biocatalytic cascade and metabolic engineering

 
* Corresponding authors

Prof Nigel ScruttonScD, FRSC, FRSB

Professor of Enzymology and Biophysical Chemistry

Abstract

The construction of biocatalytic cascades for the production of chemical precursors is fast becoming one of the most efficient approaches to multi-step synthesis in modern chemistry. However, despite the use of low solvent systems and renewably resourced catalysts in reported examples, many cascades are still dependent on petrochemical starting materials, which as of yet cannot be accessed in a sustainable fashion. Herein, we report the production of the versatile chemical building block cinnamyl alcohol from the primary metabolite and the fermentation product L-phenylalanine. Through the combination of three biocatalyst classes (phenylalanine ammonia lyase, carboxylic acid reductase and alcohol dehydrogenase) the target compound could be obtained in high purity, demonstrable at the 100 mg scale and achieving 53% yield using ambient temperature and pressure in an aqueous solution. This system represents a synthetic strategy in which all components present at time zero are biogenic and thus minimises damage to the environment. Furthermore we extend this biocatalytic cascade by its inclusion in an L-phenylalanine overproducing strain of Escherichia coli. This metabolically engineered strain produces cinnamyl alcohol in mineral media using glycerol and glucose as the carbon sources. This study demonstrates the potential to establish green routes to the synthesis of cinnamyl alcohol from a waste stream such as glycerol derived, for example, from lipase treated biodiesel.
(R)-3-amino-3-(3-fluorophenyl)propanoic acid (1c) 1H NMR (CDCl3): δ 7.16-7.31 (m, 5H, ArH), 6.50-6.54 (d, 1H, J = 16 Hz, C=CH), 6.23-6.30 (dt, 1H, J = 16, 8 Hz, C=CHCH2 ), 4.21-4.23 (dd, 2H, J = 8, 4 Hz, C=CHCH2); 13C NMR (CDCl3): 136.70, 131.09, 128.60, 128.54, 127.69, 126.48, 63.65.
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Saturday 6 January 2018

(2R,3S,4R,5R)-1-(3-((5-(4-Fluorophenyl)thiophen-2-yl)methyl)-4-methylphenyl)-2,3,4,5,6-pentahydroxyhexan-1-one

Figure
CAS 1672658-93-3
C24 H25 F O6 S, 460.52
D-Glucopyranose, 1-C-[3-[[5-(4-fluorophenyl)-2-thienyl]methyl]-4-methylphenyl]-
 
 
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CAS 1809403-04-0
C24 H25 F O6 S, 460.52
D-Glucose, 1-C-[3-[[5-(4-fluorophenyl)-2-thienyl]methyl]-4-methylphenyl]-
WO2017/93949
 
Figure
 
 
(2R,3S,4R,5R)-1-(3-((5-(4-Fluorophenyl)thiophen-2-yl)methyl)-4-methylphenyl)-2,3,4,5,6-pentahydroxyhexan-1-one    12
From the FT-IR spectra of 12 contain a signal at 1674 cm–1, this signal is strongly indicative of a carbonyl ketone being present in 12
In 13C NMR and HMBC correlations spectra, the chemical shift at 199.75 ppm was observed. Analysis of the NMR data  confirmed that the structure of 12 is a ring-opened keto form
Synthesis of (2R,3S,4R,5R)-1-(3-((5-(4-Fluorophenyl)thiophen-2-yl)methyl)-4-methylphenyl)-2,3,4,5,6-pentahydroxyhexan-1-one 12
title compound 12 (84.23% yield) and having 99.4% purity by HPLC;
 
DSC: 160.84–166.44 °C;
 
Mass: m/z 459 (M+–H);
 
IR (KBr, cm–1): 3313, 2982, 1674.7, 1601, 1507.5, 1232.7;
 
1H NMR (600 MHz, DMSO-d6) δ 7.87 (s, 1H), 7.80 (dd, J = 1.8 Hz, 1H), 7.61–7.58 (m, 2H), 7.33 (d, J = 8.4 Hz, 1H), 7.29 (d, J = 3.6 Hz, 1H), 7.21–7.18 (m, 2H), 6.84 (d, J = 3.6 Hz, 1H), 5.17 (dd, J = 3.6, 3.0 Hz, 1H), 5.02 (d, J = 6.6 Hz, 1H), 4.57 (d, J = 4.8 Hz, 1H), 4.43–4.39 (m, 3H), 4.22 (s, 2H), 4.02–4.01 (m, 1H), 3.53–3.51 (m, 3H), 3.38–3.37 (m, 1H), 2.35 (s, 3H);
 
13C NMR (101 MHz, DMSO-d6) δ 199.7, 162.6, 160.2, 142.8, 142.1, 140.5, 138.8, 133.3, 130.5, 130.4, 130.4, 129.3, 127.2, 127.0, 127.0, 126.7, 123.5, 116.0, 115.8, 75.2, 72.3, 71.8, 71.3, 63.2, 33.2, 19.2.
 
HRMS (ESI): calcd m/zfor [C24H25FO6S + Na]+ = 483.1248, found m/z 483.1244.
 
 
 
 
 
 
 
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/acs.oprd.7b00281
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Friday 29 December 2017

Stable and reusable nanoscale Fe2O3-catalyzed aerobic oxidation process for the selective synthesis of nitriles and primary amides


Green Chem., 2018, Advance Article
DOI: 10.1039/C7GC02627G, Paper
Kathiravan Murugesan, Thirusangumurugan Senthamarai, Manzar Sohail, Muhammad Sharif, Narayana V. Kalevaru, Rajenahally V. Jagadeesh
Nanoscale Fe2O3-catalyzed environmentally benign synthesis of nitriles and amides has been performed from easily accessible aldehydes and ammonia using O2.

Stable and reusable nanoscale Fe2O3-catalyzed aerobic oxidation process for the selective synthesis of nitriles and primary amides

 
Author affiliations

Abstract

The sustainable introduction of nitrogen moieties in the form of nitrile or amide groups in functionalized molecules is of fundamental interest because nitrogen-containing motifs are found in a large number of life science molecules, natural products and materials. Hence, the synthesis and functionalization of nitriles and amides from easily available starting materials using cost-effective catalysts and green reagents is highly desired. In this regard, herein we report the nanoscale iron oxide-catalyzed environmentally benign synthesis of nitriles and primary amides from aldehydes and aqueous ammonia in the presence of 1 bar O2 or air. Under mild reaction conditions, this iron-catalyzed aerobic oxidation process proceeds to synthesise functionalized and structurally diverse aromatic, aliphatic and heterocyclic nitriles. Additionally, applying this iron-based protocol, primary amides have also been prepared in a water medium.
1H NMR (300 MHz, Chloroform-d) δ 7.17 – 6.96 (m, 2H), 6.93 – 6.70 (m, 1H), 4.33 – 4.11 (m, 4H). 13C NMR (75 MHz, Chloroform-d) δ 147.75 , 143.80 , 125.87 , 121.21 , 118.91 , 118.25 , 104.38 , 64.59 , 64.12 . Off white solid
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cas 19102-07-9
  • 1,4-Benzodioxan-6-carbonitrile (8CI)
  • 2,3-Dihydro-1,4-benzodioxin-6-carbonitrile
  • 1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)nitrile

MP
Melting Point, °C  
105 - 106
Tetrahedron, 2015, vol. 71,  29, p. 4883 - 4887
NMR PREDICTS
1H NMR

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13C NMR PREDICT
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More................
Journal of the American Chemical Society, 2001, vol. 123, 49, p. 12202 - 12206
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More.............
RSC Advances, 2013, vol. 3, 44, p. 22389 - 22396
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MORE........
Organic Letters, 2017, vol. 19,  12, p. 3095 - 3098
2,3-Dihydrobenzo[b][1,4]dioxine-6-carbonitrile (Scheme 1, 2n) According to the general procedure A, the reaction of 1n (0.20 mmol), zinc cyanide (2.0 equiv), PCyPh2 (0.20 equiv) and Pd(OAc)2 (0.05 equiv) in dioxane (0.25 M) for 16 h at 150 °C, afforded after work-up and chromatography the title compound in 75% yield (24.2 mg). White solid. 1H NMR (500 MHz, CDCl3) δ 7.17-7.11 (m, 2H), 6.91 (d, J = 8.1 Hz, 1H), 4.32-4.31 (m, 2H), 4.30- 4.26 (m, 2H). 13C NMR (125 MHz, CDCl3) δ 147.84, 143.91, 126.04, 121.37, 119.01, 118.37, 104.62, 64.71, 64.24.
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Thursday 28 December 2017

Sulfurative self-condensation of ketones and elemental sulfur: a three-component access to thiophenes catalyzed by aniline acid-base conjugate pairs


Green Chem., 2018, Advance Article
DOI: 10.1039/C7GC03437G, Communication
Thanh Binh Nguyen, Pascal Retailleau
An aniline/acid-catalyzed method for constructing thiophenes 2 from inexpensive ketones 1 and elemental sulfur is reported.

Sulfurative self-condensation of ketones and elemental sulfur: a three-component access to thiophenes catalyzed by aniline acid–base conjugate pairs

 
Author affiliations

Abstract

A sulfurative self-condensation method for constructing thiophenes 2 by a reaction between ketones 1 and elemental sulfur is reported. This reaction, which is catalyzed by anilines and their salts with strong acids, starts from readily available and inexpensive materials, and releases only water as a by-product.
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2,4-Di-p-tolylthiophene (2b)2
2 M. Arisawa, T. Ichikawa, and M. Yamaguchi, Chem. Commun. 2015, 51, 8821
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Eluent heptane:toluene 9:1. 190 mg, 72%.
1 H NMR (300 MHz, CDCl3) δ 7.60-7.54 (m, 5H), 7.34 (s, 1H), 7.27-7.23 (m, 4H), 2.42 (s, 6H).
13C NMR (75 MHz, CDCl3) δ 145.3, 143.3, 137.8, 137.2, 133.5, 131.9, 129.9, 129.8, 126.5, 126.0, 122.1, 118.9, 21.5, 21.5.
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Binh Thanh Nguyen at French National Centre for Scientific Research

Binh Thanh Nguyen

CV Binh Nguyen

CNRS Research Associate CR1 ( ORCID , ResearchGate )
ICSN-CNRS Bât. 27
1, avenue de la Terrasse
91190 Gif-sur-Yvette France
thanh-binh.nguyen_at_cnrs.fr
+33 1 69 82 45 49
- Education and work experience2015: Habilitation to Direct Research (HDR)
2011 - present: CNRS research associate at ICSN - Paris-Saclay University
2009 - 2011: Post-doctoral Fellow at ICSN (Dr. Françoise Guéritte and Dr. Qian Wang)
2003 - 2006: Ph.D. student at the UCO2M Organic Synthesis Laboratory (University of Maine, Le Mans, France, Dr. Gilles Dujardin, Dr. Arnaud Martel, Professor Robert Dhal)
- Research Interests
Green chemistry (Atom, step and redox economic transformation), green synthetic tools: O2, S8, photochemistry, iron catalyst
Elemental sulfur as a synthetic tool (building block, oxidant, reductant, catalyst)
Iron-sulfur catalysts
Heterocycle synthesis
- Scientific Communications
47 publications
- Selected recent publications ( complete list )
[1] Adv. Synth. Catal. 2017 , 359 , 1106.
[2] Asian J. Org. Chem. 2017 , 6 , 477.
[3] Org. Lett. 2016 , 18 , 2177.
[4] Org. Process Res. Dev. 2016 , 20 , 319.
[5] Angew. Chem. Int. Ed. 2014 , 53 , 13808.
[6] J. Am. Chem. Soc. 2013 , 135 , 118.
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