Saturday, 3 June 2017

Synthesis of 2-substituted quinazolines by CsOH-mediated direct aerobic oxidative cyclocondensation of 2-aminoarylmethanols with nitriles in air




Green Chem., 2017, Advance Article
DOI: 10.1039/C7GC00977A, Communication
Song Yao, Kaijing Zhou, Jiabing Wang, Hongen Cao, Lei Yu, Jianzhang Wu, Peihong Qiu, Qing Xu
An atom-efficient synthesis of 2-substituted quinazolines is developed by a CsOH-mediated aerobic oxidative reaction of 2-aminoarylmethanols and nitriles in air.


http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C7GC00977A?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Synthesis of 2-substituted quinazolines by CsOH-mediated direct aerobic oxidative cyclocondensation of 2-aminoarylmethanols with nitriles in air

 Author affiliations

Abstract

By using air as the superior oxidant, a highly atom-efficient synthesis of 2-substituted quinazolines is developed by a CsOH-mediated direct aerobic oxidative reaction of the readily available and stable 2-aminoarylmethanols and nitriles. Effectively working as the promoter in the alcohol oxidation, nitrile hydration, and cyclocondensation steps, CsOH is the best base for the reaction. A similar method can also be extended to the synthesis of substituted quinolines starting from methyl ketones instead of nitriles.
Graphical abstract: Synthesis of 2-substituted quinazolines by CsOH-mediated direct aerobic oxidative cyclocondensation of 2-aminoarylmethanols with nitriles in air










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Wednesday, 10 May 2017

DR PRAVIN PATIL (Guest blogger) m-Chloroperbenzoic acid-oxchromium (VI)-mediated cleavage of 2,4,5-trisubstituted oxazoles

Here is the another publication details 
The paper is about m-CPBA/Chromium-VI mediated oxidation of oxazoles and published in Tetrahedron Letters recently.

m-Chloroperbenzoic acid-oxchromium (VI)-mediated cleavage of  2,4,5-trisubstituted oxazoles 
Pravin C. Patil and Frederick A. Luzzio*

Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292 USA

[Invited article: Tetrahedron Letters 2017, 58 (13), 1280-1282]




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Graphical Abstract:



Abstract:
An array of 2-substituted-4,5-diphenyloxazoles were found to be cleaved to triacylamines and diacylamines (imides) using a reagent system composed of 3-chloroperbenzoic acid (MCPBA) and 2,2'-bipyridinium chlorochromate (BPCC). The 2-alkyl-4,5-diphenyloxazoles give imides (38-60%) as the predominant cleavage product while the 2-aryl-4,5-diphenyloxazoles give triacylamines (62-71%). Two mechanisms involving intermediates such as cyclic endoperoxides or oxachromacycles were proposed. An application of the oxidative cleavage to the multi-step synthesis of phoracantholide I seco acid is detailed.







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Application of methodology toward synthesis of Phoracantholide-I seco acid
                                                                                          





 Highlights
A new method for the cleavage of 2,4,5-trisubstituted oxazoles to imides and triacylamines is detailed.

The oxidation system utilizes two reagents composed of a peroxide and oxochromium (VI).

Mechanisms are proposed for the oxidative cleavage reaction.

A synthesis of (±)-phoracantholide seco-acid is detailed.


ABOUT GUEST BLOGGER
Dr. Pravin C. Patil

Dr. Pravin C. Patil

Postdoctoral Research Associate at University of Louisville

Email, pravinchem@gmail.com
    Dr. Pravin C Patil completed his B.Sc. (Chemistry) at ASC College Chopda (Jalgaon, Maharashtra, India) in 2001 and M.Sc. (Organic Chemistry) at SSVPS’S Science College Dhule in North Maharashtra University (Jalgaon, Maharashtra, India) in year 2003. After M.Sc. degree he was accepted for summer internship training program at Bhabha Atomic Research Center (BARC, Mumbai) in the laboratory of Prof. Subrata Chattopadhyay in Bio-organic Division. In 2003, Dr. Pravin joined to API Pharmaceutical bulk drug company, RPG Life Science (Navi Mumbai, Maharashtra, India) and worked there for two years. In 2005, he enrolled into Ph.D. (Chemistry) program at Institute of Chemical Technology (ICT), Matunga, Mumbai, aharashtra, under the supervision of Prof. K. G. Akamanchi in the department of Pharmaceutical Sciences and Technology.
    After finishing Ph.D. in 2010, he joined to Pune (Maharashtra, India) based pharmaceutical industry, Lupin Research Park (LRP) in the department of process development. After spending two years at Lupin as a Research Scientist, he got an opportunity in June 2012 to pursue Postdoctoral studies at Hope College, Holland, MI, USA under the supervision of Prof. Moses Lee. During year 2012-13 he worked on total synthesis of achiral anticancer molecules Duocarmycin and its analogs. In 2014, he joined to Prof. Frederick Luzzio at the Department for Chemistry, University of Louisville, Louisville, KY, USA to pursue postdoctoral studies on NIH sponsored project “ Structure based design and synthesis of Peptidomimetics targeting P. gingivalis.
    During his research experience, he has authored 23 international publications in peer reviewed journals and inventor for 4 patents.
    //////////////guest blogger, pravin patil

    Saturday, 29 April 2017

    Visible-light-induced and iron-catalyzed methylation of N-arylacrylamides with dimethyl sulphoxide: a convenient access to 3-ethyl-3-methyl oxindoles

    Visible-light-induced and iron-catalyzed methylation of N-arylacrylamides with dimethyl sulphoxide: a convenient access to 3-ethyl-3-methyl oxindoles

    Org. Biomol. Chem., 2017, Advance Article
    DOI: 10.1039/C7OB00779E, Paper
    Zuguang Xie, Pinhua Li, Yu Hu, Ning Xu, Lei Wang
    An efficient synthesis of 3-ethyl-3-methyl oxindoles by visible-light promoted and iron-catalyzed difunctionalization of N-arylacrylamides with dimethyl sulphoxide was developed

    Visible-light-induced and iron-catalyzed methylation of N-arylacrylamides with dimethyl sulphoxide: a convenient access to 3-ethyl-3-methyl oxindoles

    Abstract

    A visible-light-induced and iron-catalyzed methylation of arylacrylamides by dimethyl sulphoxide (DMSO) is achieved, leading to 3-ethyl-3-methyl indolin-2-ones in high yields. This reaction tolerates a series of functional groups, such as methoxy, trifluoromethyl, cyano, nitro, acetyl and ethyloxy carbonyl groups. The visible-light promoted radical methylation and arylation of the alkenyl group are involved in this reaction.
    Graphical abstract: Visible-light-induced and iron-catalyzed methylation of N-arylacrylamides with dimethyl sulphoxide: a convenient access to 3-ethyl-3-methyl oxindoles
    str1 str2
     
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    N-Methyl-3-Bromo-5-Methyl Pyrazole

    N-Methyl-3-Bromo-5-Methyl Pyrazole

    3·HCl as a white solid in 27% yield; sublimes at 40 °C; 1H NMR (500 MHz, DMSO-d6) δ 11.88 (s, 1 H), 6.07 (s, 1 H), 3.62 (s, 3 H), 2.16 (s, 3 H); 13C NMR (125 MHz, DMSO-d6) δ 141.7, 123.0, 107.5, 36.5, 10.9; HRMS-ESI (m/z) calcd for C5H8N2Br [M + H]+ 174.9864, found 174.9864.
    3·TfOH as an off-white solid; mp = 145 °C; 1H NMR (400 MHz, DMSO-d6) δ 11.73 (s, 1 H), 6.06 (s, 1 H), 3.62 (s, 3 H), 2.16 (s, 3 H); 13C NMR (100 MHz, DMSO-d6) δ 141.9, 123.2, 121.2 (q, J = 320 Hz), 107.6, 36.5, 10.9; HRMS-ESI (m/z) calcd for C5H8N2Br [M + H]+ 174.9864, found 174.9865.

    Development of Scalable Processes for the Preparation of N-Methyl-3-Bromo-5-Methyl Pyrazole

    Chemical & Synthetic Development, Bristol-Myers Squibb Company, P.O. Box 191 New Brunswick, New Jersey 08903-0191, United States
    Org. Process Res. Dev., Article ASAP
    DOI: 10.1021/acs.oprd.7b00091
     
    Abstract Image
    The development and optimization of two scalable routes to N-methyl-3-bromo-5-methyl pyrazole is described. The initial Sandmeyer route entailed a three-step sequence from crotonitrile and methyl hydrazine, proceeding through the 3-amino pyrazole intermediate. Due to the GTI liability of the 3-amino pyrazole intermediate, a tedious steam-distillation, and <30% overall yield, we developed a second-generation Sandmeyer-free approach from methyl crotonate and methyl hydrazine which leveraged a condensation, bromination, and oxidation sequence. Process development led to the improved preparation of N-methyl-3-bromo-5-methyl pyrazole with increased efficiency and overall yield. The isolation, handling, and storage of the final product was greatly improved through the generation of the triflic acid salt, and salt form studies are also discussed.
    str1 str2 str3 str4
    Org. Process Res. Dev., Article ASAP
    DOI: 10.1021/acs.oprd.7b00091
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    Asymmetric synthesis of ent-fragransin C1

    Asymmetric synthesis of ent-fragransin C1

    Org. Biomol. Chem., 2017, Advance Article
    DOI: 10.1039/C7OB00749C, Paper
    Santikorn Chaimanee, Manat Pohmakotr, Chutima Kuhakarn, Vichai Reutrakul, Darunee Soorukram
    The first asymmetric synthesis of ent-fragransin C1 bearing 2,3-anti-3,4-syn-4,5-anti stereochemistries is reported.

    Asymmetric synthesis of ent-fragransin C1

    Abstract

    The first asymmetric synthesis of ent-fragransin C1 was reported. The key step involves an intramolecular C–O bond formation (furan ring formation) via chemoselective generation of the benzylic carbocation leading to the 2,3-anti-3,4-syn-4,5-anti-tetrahydrofuran moiety as a single diastereomer in good yield. Our synthesis confirms that ent-fragransin C1 possesses 2R,3R,4S,5S configurations.
    4-[(2R,3R,4S,5S)-5-(4-Hydroxy-3-methoxyphenyl)-3,4- dimethyltetrahydrofuran-2-yl]-2,6-dimethoxyphenol (ent-1). A flame-dried.......................... in vacuo, the crude product was purified by column chromatography (60% EtOAc in hexanes) to afford ent-1 as a sticky brownish oil (15.3 mg, 99% yield) as a single diastereomer (400 MHz 1 H NMR analysis). Rf 0.18 (40% EtOAc in hexanes);
    [α]27 D -6.97 (c 0.60, CHCl3 ) (lit. [α]D +3.8 (c 0.60, CHCl3 ); 4a
    UV (MeOH) λmax (log ε) 208 (0.85), 233 (0.24), 279 (0.07) nm; CD (MeOH) 226 (Δε 2.23), 250 (Δε +0.12).
    1 H NMR (400 MHz, acetone-d6 ): δ 7.51 (s, 1H, OH), 7.12 (s, 1H, OH), 7.10 (d, J = 1.8 Hz, 1H, ArH), 6.92 (d, J = 8.1, 1.8 Hz, 1H, ArH), 6.82 (d, J = 8.1 Hz, 1H, ArH), 6.77 (s, 2H, 2  ArH), 4.43 (d, J = 5.4 Hz, 1H, 2  xCH), 3.86 (s, 3H, OCH3 ), 3.83 (s, 6H, 2  xOCH3 ), 2.202.45 (m, 2H, 2  xCH), 1.03 (d, J = 6.7 Hz, 3H, CH3 ), 1.00 (d, J = 6.7 Hz, 3H, CH3 ).
    13C NMR (100 MHz, acetone-d6 ): δ 149.0 (2  C), 148.7 (C), 147.3 (C), 136.6 (C), 135.5 (C), 134.7 (C), 120.4 (CH), 115.9 (CH), 111.2 (CH), 105.1 (2  CH), 88.7 (CH), 88.4 (CH), 57.0 (2  CH3 ), 56.6 (CH3 ), 46.1 (CH), 45.7 (CH), 13.7 (CH3 ), 13.5 (CH3 ).
    IR (CHCl3 ): νmax 3542s, 1616m, 1517s, 1465s, 1117s cm−1 .
    MS (ISCID): m/z (%) relative intensity 397 [(M + Na)+ , 100], 357 (1).
    HRMS (ESI-TOF) calcd for C21H26O6Na [M + Na]+ : 397.1627, found: 397.1622.
    4 (a) M. Hattori, S. Hada, Y. Kawata, Y. Tezuka, T. Kikuchi and T. Namba, Chem. Pharm. Bull., 1987, 35, 3315; (

    Image result for Darunee Soorukram Mahidol University
    Darunee Soorukram
    Assistant Professor

    Darunee Soorukram

    Education
    • B.Sc. (Chemistry), Khon Kean University, Khon Kean, Thailand
    • M.Sc. (Organic Chemistry), Mahidol University, Bangkok, Thailand
    • Ph.D., Ludwig-Maximilians-University, Munich, Germany
    Name :Darunee Soorukram 
     ดรุณี สู้รักรัมย์
    Title :Assistant Professor Dr.
    Education :Ph.D. (Ludwig-Maximilians-University), Germany
      
    Expertise :-
      
    Contact Address :Department : Chemistry
     Room : C418B
     Phone : (662) 201 5148 
     E-Mail : darunee.soo@mahidol.ac.th 
       
    More Information :CV from Dept. Chemistry Website   
     รางวัลวิทยานิพนธ์ ระดับดีเยี่ยม (สาขาวิทยาศาสตร์เคมีและเภสัช) จากสภาวิจัยแห่งชาติ 

    Most Recent Articles from Scopus : Soorukram D (Author ID: 6506453550)

    Contact
    Phone: +66.(0).2.201.5148
    LAB Tel: +66.(0).2.201.5149
    Fax: +66.(0).2.354.7151
    E-mail:darunee.soo@mahidol.ac.th
    Address:
    Room C418B
    Department of Chemistry,
    Faculty of Science, Mahidol University,
    Rama 6 Road, Ratchthewee
    Bangkok 10400 Thailand
    /////////

    Tuesday, 4 April 2017

    Palladium-catalyzed coupling of azoles with 1-aryltriazenes via C–H/C–N cleavage

     

    Palladium-catalyzed coupling of azoles with 1-aryltriazenes via C–H/C–N cleavage

    *Corresponding authors

    Abstract

    In the presence of CuCl and ButOLi, PdCl2/dppe catalyzes the reaction of (benzo)oxazoles or (benzo)thiazoles with 1-aryltriazenes to yield arylated products of (benzo)oxazoles or (benzo)thiazoles. Functional groups including F, Cl, CF3, COOEt, CN, OMe, NMe2, Py, and thienyl groups can be tolerated.
    Graphical abstract: Palladium-catalyzed coupling of azoles with 1-aryltriazenes via C–H/C–N cleavage

    Regioselective acylation and carboxylation of [60]fulleroindoline via electrochemical synthesis

        str5
    3a (11.2 mg, 38%) were obtained along with unreacted 1 (1.1 mg, 4%).
    1H NMR (400 MHz, CS2/CDCl3) δ 8.39 (d, J = 8.0 Hz, 2H), 7.60 (t, J = 7.4 Hz, 1H), 7.50 (t, J = 7.7 Hz, 2H), 7.41 (d, J = 7.8 Hz, 1H), 7.29 (s, 1H), 7.04 (d, J = 7.8 Hz, 1H), 5.95 (s, 1H), 2.76 (s, 3H), 2.52 (s, 3H);
    13C NMR (100 MHz, CS2/CDCl3, all 1C unless indicated) δ 196.06 (C=O), 167.78 (C=O), 152.39, 152.08, 151.38, 150.04, 149.83, 149.22, 148.81, 148.52, 148.26, 147.93, 147.86, 147.73, 147.36, 147.18, 147.14 (2C), 146.91, 146.86, 146.41, 146.40, 145.99 (2C), 145.95, 145.92, 145.53, 145.37, 145.33, 144.82 (2C), 144.80, 144.72, 144.54, 144.42, 144.31, 144.14, 143.84, 143.65, 143.42, 143.31, 143.05, 142.13, 141.93, 141.79, 141.72 (2C), 141.69, 141.55, 141.35, 141.24, 141.10, 140.63, 140.14, 139.93 (aryl C), 138.84, 137.70, 137.54 (aryl C), 137.47, 137.38, 135.44 (aryl C), 133.14 (aryl C), 129.16 (2C, aryl C), 128.72 (2C, aryl C), 128.61 (aryl C), 125.80 (aryl C), 125.42 (aryl C), 115.11 (aryl C), 83.58 (sp3 -C of C60), 69.89 (sp3 -C of C60), 62.42 (sp3 -C of C60), 56.81 (sp3 -C of C60), 26.84, 22.25;
    UV-vis (CHCl3) λmax nm (log ε) 251.0 (5.1), 318.5 (4.6), 403.5 (4.0), 440.0 (3.9), 525.5 (3.2), 703.5 (2.5);
    FT-IR ν/cm-1 (KBr) 2922, 2860, 1668, 1599, 1499, 1439, 1366, 1304, 1236, 1180, 1086, 1020, 964, 858, 802, 748, 691, 604, 528;
    MALDI-TOF MS m/z calcd for C76H16NO2 [M+H]+ 974.1176, found 974.1165.

    Regioselective acylation and carboxylation of [60]fulleroindoline via electrochemical synthesis

    Abstract

    A regioselective and highly efficient electrochemical method for direct acylation and carboxylation of a [60]fulleroindoline has been developed. By using inexpensive and readily available acyl chlorides and chloroformates, both keto and ester groups can be easily attached onto the fullerene skeleton to afford 1,2,3,16-functionalized [60]fullerene derivatives regioselectively. In addition, a plausible mechanism for the formation of fullerenyl ketones and esters is proposed, and their further transformations under basic and acidic conditions have been investigated.