DR ANTHONY MELVIN CRASTO,WorldDrugTracker, helping millions, A 90 % paralysed man in action for you, I am suffering from transverse mylitis and bound to a wheel chair, With death on the horizon, nothing will not stop me except God................DR ANTHONY MELVIN CRASTO Ph.D ( ICT, Mumbai) , INDIA 25Yrs Exp. in the feld of Organic Chemistry,Working for GLENMARK GENERICS at Navi Mumbai, INDIA. Serving chemists around the world. Helping them with websites on Chemistry.Million hits on google, world acclamation from industry, academia, drug authorities for websites, blogs and educational contribution

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).
STR1 STR2 STR3

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.
//////////

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.
STR1 STR2

////////////cinnamyl alcohol,  biocatalytic, metabolic engineering

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]-
 
 
str1
str1
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
////////////