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Showing posts with label ORGANIC Synthesis. Show all posts
Showing posts with label ORGANIC Synthesis. Show all posts

Saturday, 7 May 2016

N-Butylpyrrolidinone as a dipolar aprotic solvent for organic synthesis


Green Chem., 2016, Advance Article
DOI: 10.1039/C6GC00932H, Paper
James Sherwood, Helen L. Parker, Kristof Moonen, Thomas J. Farmer, Andrew J. Hunt
N-Butylpyrrolidinone (NBP) has been demonstrated as a suitable safer replacement solvent for N-Methylpyrrolidinone (NMP) in selected organic syntheses.

N-Butylpyrrolidinone as a dipolar aprotic solvent for organic synthesis

*Corresponding authors
aGreen Chemistry Centre of Excellence, Department of Chemistry, University of York, UK
E-mail: andrew.hunt@york.ac.uk
bEastman Chemical Company, Pantserschipstraat 207 – B-9000, Gent, Belgium
Green Chem., 2016, Advance Article
DOI: 10.1039/C6GC00932H
 
Dipolar aprotic solvents such as N-methylpyrrolidinone (or 1-methyl-2-pyrrolidone (NMP)) are under increasing pressure from environmental regulation. NMP is a known reproductive toxin and has been placed on the EU “Substances of Very High Concern” list. Accordingly there is an urgent need for non-toxic alternatives to the dipolar aprotic solvents. N-Butylpyrrolidinone, although structurally similar to NMP, is not mutagenic or reprotoxic, yet retains many of the characteristics of a dipolar aprotic solvent. This work introduces N-butylpyrrolidinone as a new solvent for cross-coupling reactions and other syntheses typically requiring a conventional dipolar aprotic solvent.

str1
////N-Butylpyrrolidinone, dipolar aprotic solvent , organic synthesis

Friday, 30 May 2014

Visible-light-induced photocatalytic formyloxylation reactions of 3-bromooxindoles with water and DMF: the scope and mechanism

Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00647J, Paper
You-Quan Zou, Wei Guo, Feng-Lei Liu, Liang-Qiu Lu, Jia-Rong Chen, Wen-Jing Xiao
A highly efficient visible light induced formyloxylation reaction of 3-bromooxindoles was disclosed. Results of labeling experiments indicated that H2O and DMF were incorporated into the terminal 3-formyloxyoxindoles.
To cite this article before page numbers are assigned, use the DOI form of citation above.
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The formyloxylation reaction of 3-bromooxindoles with water and N,N-dimethylformamide (DMF) has been developed in the presence of the photoredox catalyst fac-Ir(ppy)3 under irradiation of visible light at ambient temperature. The reaction provides a straightforward approach to pharmaceutically and synthetically useful 3-formyloxyoxindoles in high yields. The mechanism of this transformation was investigated by fluorescence quenching experiments, “on–off” switching of the light source, labeling experiments, mass spectral analyses and in situ IR experiments.




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Friday, 6 December 2013

Selection of boron reagents for Suzuki–Miyaura coupling

Graphical abstract: Selection of boron reagents for Suzuki–Miyaura coupling

 Suzuki–Miyaura (SM) cross-coupling is arguably the most widely-applied transition metal catalysed carbon–carbon bond forming reaction to date. Its success originates from a combination of exceptionally mild and functional group tolerant reaction conditions, with a relatively stable, readily prepared and generally environmentally benign organoboron reagent. A variety of such reagents have been developed for the process, with properties that have been tailored for application under specific SM coupling conditions. This review analyses the seven main classes of boron reagent that have been developed. The general physical and chemical properties of each class of reagent are evaluated with special emphasis on the currently understood mechanisms of transmetalation. The methods to prepare each reagent are outlined, followed by example applications in SM coupling.
http://pubs.rsc.org/en/content/articlehtml/2014/cs/c3cs60197h

Review Article

Selection of boron reagents for Suzuki–Miyaura coupling

*
Corresponding authors
a
School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, UK

Chem. Soc. Rev., 2014,43, 412-443

DOI: 10.1039/C3CS60197H
Received 12 Jun 2013, First published online 03 Oct 2013 

Friday, 8 November 2013

Conversion of sugars to ethylene glycol with nickel tungsten carbide in a fed-batch reactor: high productivity and reaction network elucidation

Green Chem., 2013, Advance Article
DOI: 10.1039/C3GC41431K, Paper
Roselinde Ooms, Michiel Dusselier, Jan A. Geboers, Beau Op de Beeck, Rick Verhaeven,
Elena Gobechiya, Johan A. Martens, Andreas Redl, Bert F. Sels
Fed-batch reactor technology was used for the highly productive conversion of
concentrated sugar solutions into ethylene glycol using bifunctional nickel tungsten
carbide catalysts.

Conversion of sugars to ethylene glycol with nickel tungsten carbide

 in a fed-batch reactor: high productivity and reaction 

network elucidation

 

 http://pubs.rsc.org/en/Content/ArticleLanding/2013/GC/C3GC41431K?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

 

 

 Bifunctional nickel tungsten carbide catalysis was used for the conversion of aqueous sugar

 solutions into short-chain polyols such as ethylene glycol. It is shown that very concentrated sugar 

solutions, viz. up to 0.2 kg L−1, can be converted without loss of ethylene glycol selectivity 

by gradually feeding the sugar solution. Detailed investigation of the reaction network

 shows that, under the applied reaction conditions, glucose is converted via a retro-aldol

 reaction into glycol aldehyde, which is further transformed into ethylene glycol by hydrogenation. 

The main byproducts are sorbitol, erythritol, glycerol and 1,2-propanediol. 

They are formed through a series of unwanted side reactions including 

hydrogenation, isomerisation, hydrogenolysis and dehydration. 

Hydrogenolysis of sorbitol is only a minor source of ethylene glycol. To assess the 

relevance of the fed-batch system in biomass conversions, both the influence of the

 catalyst composition and the reactor setup parameters like temperature, pressure 

and glucose addition rate were optimized, culminating in ethylene glycol yields up to 66% and

 separately, volume productivities of nearly 300 gEG L−1 h−1.

Tuesday, 29 October 2013

Synthesize 7-azanorbornane on an industrial scale

Synthesize 7-azanorbornane on an industrial scale
Patent Number:US 8404865
Title:Process for preparing azabicyclic compounds
Inventor(s):Ambhaikar, Narendra Bhalchandra; Bear, Brian Richard; Fanning, Lev T. D.; Hughes, Robert; Littler, Benjamin
Patent Assignee(s):Vertex Pharmaceuticals Incorporated, USA
Source:U.S. Pat. Appl. Publ., 8pp. CODEN: USXXCO
Language:English
Abstract:The present invention relates to a process for prepg. azabicyclic compds. that are useful intermediates for synthesizing pharmaceutical compds. or salts thereof.  Thus, azabicyclo[2.2.1]heptane hydrochloride (I·HCl) was prepd. from trans-4-aminocyclohexanol via N-protection with Boc2O in CH2Cl2 contg. Et3N; mesylation with MsCl in CH2Cl2 contg. Et3N; N-deprotection with CF3CO2H; cyclization with aq. NaOH; and treatment with
7-azabicyclo[2.2.1]heptanes are useful intermediates in the synthesis of pharmaceutical compounds and salts thereof. For example, see U.S. Pat. Nos. 6,117,889 and 6,060,473, each of which is hereby incorporated by reference in its entirety
 Despite the title of N. B. Ambhaikar and co-inventors’ patent, “Process for preparing azabicyclic compounds”, it only describes a process for preparing 7-azanorbornane (5) and its HCl salt (6). The inventors state that compound 5 is an intermediate in the synthesis of pharmaceutical compounds, but they do not mention any.


The patent’s examples describe the preparation of 5 and its precursors on a kilogram scale. The first step is protecting the amino group in 1 by converting it to tert-butoxycarbonyl (BOC) derivative 2 with the anhydride (BOC)2O in the presence of Na2CO3. The product is isolated in 88.8% yield. The reaction can also be carried out with K2CO3, but the yield is not reported.
Four-step synthesis of 7-azanorbornane
In the second step, 2 is treated with methanesulfonyl chloride (MsCl) in the presence of Et3N to form methanesulfonate 3 in 96.6% isolated yield. In step three, the BOC group is removed by adding CF3CO2H in two batches. The product is amine salt 4. The recovered salt contains excess CF3CO2H; and as a result, the yield appears to be >100%.
In the final stage, the CF3CO2H salt is treated with NaOH to cyclize it to the desired compound. Azanorbornane 5 is recovered by fractional distillation; treating the fractions with concd HCl gives hydrochloride salt 6. The salt is recovered as a solid, dried, and recrystallized from MeOH and MeOH–THF. Although the examples contain significant detail, the product’s final yield and purity are not reported.
The process is an efficient method for preparing 7-azanorbornane and its salt. It is clearly suitable for large-scale production. (Vertex Pharmaceuticals [Cambridge, MA]. US Patent 8,404,865, March 26, 2013; Keith Turner)
NMR
 7-azanorbornane HCl salt (6). 
1HNMR (DMSO-d6) ppm 8.02-8.04 (d); 7.23-7.31 (m); 4.59 (s); 3.31 (s); 2.51-3.3 (m); 1.63-1.75 (m); 1.45-1.62 (m).

In one aspect, the invention includes a process for preparing Compound 7-azanorbornane
PL IGNORE NUMBER 7
Figure US08404865-20130326-C00001
    • or a pharmaceutically acceptable salt thereof, comprising contacting trans-4-aminocyclohexanol with Boc anhydride to produce a compound of formula A
Figure US08404865-20130326-C00002
    • contacting a compound of formula A with methanesulfonic acid to produce a compound of formula B
Figure US08404865-20130326-C00003
    • contacting a compound of formula B with trifluoroacetic acid to produce a compound of formula C
Figure US08404865-20130326-C00004
    • contacting a compound of formula C with hydroxide to produce a compound of formula 
In some embodiments, the invention includes a method of producing a compound of formula 7-azanorbornane Hydrocloride salt
Figure US08404865-20130326-C00005
    • The TFA salt of trans-4-aminocyclohexylmethanesulfonate (200 g, 650.9 mmol) was introduced into a 3-necked flask followed by the addition of water (2.200 L, 11 vol). NaOH (78.11 g, 1.953 mol, 3 eq) was slowly added, keeping the temperature of the reaction mixture below 25° C. and the mixture was stirred overnight. DCM (1.4 L, 7 vol) was then added and the mixture stirred, and the organic layer was separated. The aqueous layer was then extracted a second time with DCM (1.4 L, 7 vol), and the DCM layers were combined. HCl (108.5 mL, 12M, 1.3020 mol, 2 eq) was then added, the mixture was stirred for 30 min and then concentrated on a rotary evaporator to dryness. Acetonitrile (10 vol) was added and the mixture concentrated. This was repeated 3 times until all trace water was azeotropically removed, to provide 7-azabicyclo[2.2.1]heptane hydrochloride. The crude product was recrystallized from acetonitrile (10 vol) to provide 7-azabicyclo[2.2.1]heptane hydrochloride as a colorless crystalline solid.

Monday, 14 October 2013

A Novel Solid-Phase Synthesis of Quinolines

Short Paper | Regular issue | Vol 85, No. 3, 2012, pp.667-676
Published online: 26th January, 2012
DOI: 10.3987/COM-11-12411
 A Novel Solid-Phase Synthesis of Quinolines
E Tang,* Deshou Mao, Wen Li, Zhangyong Gao, and Pengfei Yao
*School of Chemical Science and Technology, Yunnan University, No. 2 Green Lake North Road, Kunming 650091, China
Abstract
A method for synthesizing substituted-quinolines using TMSOTf-catalyzed polystyrene-supported succinimidyl selenide-induced intramolecular seleno-arylation of tethered alkenes as a key step has been developed. The catalytic process provides an efficient method for the stereoselective and regioselective synthesis of tetrahydroquinoline possessing a seleno-functionality, followed by deprotection of tosyl group and syn-elimination of selenoxides to provide quinolines in good yields and purities.


 http://www.heterocycles.jp/newlibrary/payments/form/22246/fulltext

Monday, 7 October 2013

Catalyst Calls The Shots - Organic Synthesis: Iron-based catalyst controls selectivity in C–H oxidations

A reaction scheme showing Fe(PDP), top, and Fe(CF3-PDP) catalysts selectively oxidizing different C–H bonds (yellow and green) in the same isoleucine substrate.
 
Iron catalysts selectively oxidize different C–H bonds (yellow and green) in the same isoleucine substrate, reactions that would otherwise require independent synthetic routes from different starting materials.

Chemists have developed a new catalyst that accelerates oxidation of C–H bonds selectively in nonaromatic compounds such as terpenes, rather than relying on the inherent properties of the reactant molecules. The catalyst could boost the versatility with which organic compounds can be synthesized for drug discovery and other applications.
read all at


Sunday, 1 September 2013

Synthesis of Tolvaptan

Synthesis of Tolvaptan


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YANG Chuanwei~1,MU Shuai~2,LIU Ying~3,WANG Pingbao~3,LIU Dengke~(3*) 
(1.School of Pharmacy,Henan University,Kaifeng 475004;2.
School of Chemical Engineering and Technology,
 Tianjin University,Tianjin 300072;3.
Tianjin Institute of Pharmaceutical Research,Tianjin 300193)  
Tolvaptan,a selective nonpeptide arginine vasopressin V_2 receptor antagonist,was synthesized
 from 7-chloro-5-oxo-2,3,4,5-tetrahydro-1H-1-benzazepine by acylation and reduction to give 1-(4-amino-2-methylbenzoyl) -7- chloro-5-oxo-2,3,4,5-tetrahydro-1H-1-benzazepine,which was subjected to acylation with 2-methylbenzoyl chloride and reduction with sodium borohydride with an overall yield of about 45%.
CAJViewer7.0 supports all the CNKI file formats; AdobeReader only supports the PDF format.
【Citations】
Chinese Journal Full-text Database2 Hits
1LI Fan1, HOU Xingpu2, LI Lin1, LU Tao1, DU Yumin1 (1. School of Pharmacy,
Hebei Medical University, Shijiazhuang 050017; 2. Shijiazhuang
 Pharma Group NBP Pharmaceutical Co., Ltd., Shijiazhuang 052160);
Synthesis of Antiparkinsonian Agent Istradefylline[J];Chinese Journal of Pharmaceuticals;2010-04
2YANG Miao~1,SHUAI Jun~2,LIU Mo~3,LIU Deng-ke~(3*),WANG Ping-bao~3
(1.Tianjin Medical University,Tianjin 300070;2.Tianjin University;Tianjin 300072;
 3.Tianjin Institute of Pharmaceutical Research,Tianjin 300193);
Synthesis of 7-Chloro-5-oxo-2,3,4,5-tetrahydro-1H-1-benzazepine[J];
Chinese Journal of Pharmaceuticals;2009-09
【Co-citations】
Chinese Journal Full-text Database1 Hits
1XIONG Xiao-yi,CHEN An-qun,HE Yong-mei(Chongqing Unis Chemical Co.,Ltd.,Chongqing
402161,China);Analysis of Cyanoacetic Acid Content by HPLC[J];Guangzhou Chemical Industry;2010-12

Wednesday, 21 August 2013

Direct synthesis of hydrogen peroxide in water in a continuous trickle bed reactor optimized to maximize productivity



Hydrogen peroxide direct synthesis was studied in continuous mode over a 5% wt Pd/C commercial catalyst in a Trickle Bed Reactor. The target of the study was to maximize the hydrogen peroxide production. The catalyst was uniformly diluted in quartz sand at different concentrations to investigate their effects on the direct synthesis.
The amount of catalyst and the distribution of the catalyst along the bed were optimized to obtain the highest possible yield. The distribution of the catalyst along the bed gave the possibility to significantly improve the selectivity and production of hydrogen peroxide (up to 0.5% under selected conditions). Higher production rate and selectivity were found when the catalyst concentration was decreased along the bed from the top to the bottom as compared to the uniformly dispersed catalyst.
The H2/Pd ratio was found to be an important parameter that has to be investigated in the hydrogen peroxide direct synthesis. The effect of a pretreatment of the catalyst with a solution of sodium bromide and phosphoric acid was studied; the results showed how a catalyst pretreatment can lead to a real green hydrogen peroxide synthesis in water. Some optimization guidelines are also provided.
Green Chem., 2013, 15,2502-2513
DOI: 10.1039/C3GC40811F, Paper


*
Corresponding authors
a
Department of Chemical Engineering, Åbo Akademi University, Turku/Åbo, Finland
E-mail: bpierdom@abo.fi ;
Fax: +358 2 215 4479 ;
Tel: +358 2 215 4555
b
Department of Chemical Engineering and Environmental Technology, University of Valladolid, Valladolid, Spain
E-mail: jgserna@iq.uva.es
Hydrogen peroxide direct synthesis was studied in continuous mode over a 5% wt Pd/C commercial catalyst in a Trickle Bed Reactor.

Friday, 16 August 2013