Monday, 26 January 2015

A Novel and Practical Synthesis of Ramelteon

Abstract Image
An efficient and practical process for the synthesis of ramelteon 1, a sedative-hypnotic, is described. Highlights in this synthesis are the usage of acetonitrile as nucleophilic reagent to add to 4,5-dibromo-1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-one 2 and the subsequent hydrogenation which successfully implement four processes (debromination, dehydration, olefin reduction, and cyano reduction) into one step to produce the ethylamine compound 13where dibenzoyl-l-tartaric acid is selected both as an acid to form the salt in the end of hydrogenation and as the resolution agent. Then, target compound 1 is easily obtained from13 via propionylation. The overall yield in this novel and concise process is almost twice as much as those in the known routes, calculated on compound 2.

A Novel and Practical Synthesis of Ramelteon

State Key Lab of New Drug & Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, State Institute of Pharmaceutical Industry, Shanghai 200437,China
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/op500386g
Publication Date (Web): January 6, 2015
Copyright © 2015 American Chemical Society
*Telephone: +86 21 55514600. E-mail:
Preparation of (S)-N-[2-(1,6,7,8-Tetrahydro-2H-indeno[5,4-b] furan-8-yl)ethyl]propionamide(1).
white solid of 1(1.570 g, 85% yield, 99.8% ee). Purity by HPLC 99.6%.
Mp: 115−116 °C(113−115°C in literature 1 ).
1 H−NMR(400 MHz, CDCl3):
δ 1.39 (t, 3H); 1.63 (m, 1H); 1.83 (m, 1H); 2.02 (m, 1H); 2.16 (dd, J=8, 2H); 2.28 (m, 1H); 2.78 (m, 1H); 2.83 (m, 1H); 3.14 (m, 1H); 3.22 (m, 2H); 3.33 (m, 2H); 4.54 (m, 2H); 5.38 (br s, 1H); 6.61 (d, J=8, 1H); 6.97 (d, J=8, 1H).
13C−NMR(100 MHz, CDCl3):
δ 173.85, 159.56, 143.26, 135.92, 123.52, 122.28, 107.56, 71.26, 42.37, 38.17, 33.66, 31.88, 30.82, 29.86, 28.73, 10.01.
MS (ES+): m/z 282(M+Na) + .
[α]D −57.3(c=1.0, CHCl3, −57.8 in literature 1 ).
Anal. (C16H21NO2) Calc: C, 74.10; H, 8.16; N, 5.40; found: 74.09; H, 8.17; N, 5.47.
(1) Uchikawa, O.; Fukatsu, K.; Tokunoh, R.; Kawada, M.; Matsumoto, K.; Imai, Y.; Hinuma, S.; Kato, K.; Nishikawa, H.; Hirai, K.; Miyamoto M.; Ohkawa, S. J. Med. Chem. 2002, 45, 4222-4239.
(2) Yamano, T.; Yamashita, M.; Adachi, M.; Tanaka, M.; Matsumoto, K.; Kawada, M.; Uchikawa, O.; Fukatsu, K.; Ohkawa, S. Tetrahedron: Asymmetry. 2006, 17, 184-190.
The Shanghai International Exhibition Center, an example of Soviet neoclassical architecture in Shanghai

Sunday, 25 January 2015

Bulletin of the Chemical Society of Ethiopia

Journal Homepage Image


Federal Democratic Republic of Ethiopia
የኢትዮጵያ ፌዴራላዊ ዲሞክራሲያዊ

ye-Ītyōṗṗyā Fēdēralāwī Dīmōkrāsīyāwī

Coins of the Axumite king Endybis, 227–235 AD, at the British Museum. The inscriptions in Ancient Greek read "AΧWMITW BACIΛEYC" ("King of Axum") and "ΕΝΔΥΒΙC ΒΑCΙΛΕΥC" ("King Endybis").

Mountain nyalas in Nechisar National Park, one of several wildlife reserves in Ethiopia.


Journal Home
 > Vol 29, No 1 (2015) > 

Regioselective iodination of aryl amines using 1,4-dibenzyl-1,4-diazoniabicyclo [2.2.2] octane dichloroiodate in solution and under solvent-free conditions

M. Alikarami, S. Nazarzadeh, M. Soleiman-Beigi


1,4-Dibenzyl-1,4-diazoniabicyclo[2.2.2]octane dichloroiodate is an efficient and regioselective reagent for iodination of aryl amines. A wide variety of aryl amines in reaction with this reagent afforded regioselectively iodinated products. The iodination reaction can be carried out in solution or under solvent-free condition at room temperature.

KEY WORDS:  Regioselective iodination, Aryl amines, 1,4-Dibenzyl-1,4-diazoniabicyclo [2.2.2] octane dichloroiodate,  Solvent-free conditions

Bull. Chem. Soc. Ethiop. 2015, 29(1), 157-162

Sunday, 11 January 2015

"Pd/NHC-Catalyzed Enantiospecific and Regioselective Suzuki-Miyaura Arylation of 2-Arylaziridines: Synthesis of Enantioenriched 2-Arylphenethylamine Derivatives"

"Pd/NHC-Catalyzed Enantiospecific and Regioselective Suzuki-Miyaura Arylation of 2-Arylaziridines: Synthesis of Enantioenriched 2-Arylphenethylamine Derivatives"
Youhei Takeda*, Yuki Ikeda, Akinobu Kuroda, Shino Tanaka, and Satoshi Minakata*
J. Am. Chem. Soc. 2014136, 8544–8547. DOI: 10.1021/ja5039616 

* Highlighted in Org. Process Res. Dev. as "Some Items of Interest to Process R&D Chemists and Engineers"! !link
Abstract: A palladium-catalyzed stereospecific and regioselective cross-coupling of enantiopure 2-arylaziridines with arylboronic acids under mild conditions to construct a tertiary stereogenic center has been developed. N-heterocyclic carbene (NHC) ligands drastically promote the coupling, suppressing β-hydride elimination. The enantiospecific cross-coupling allowed us for preparation of a series of biologically important 2-arylphenethylamine derivatives in an enantiopure form.

Utilization of N-X bonds in the synthesis of N-heterocycles

Utilization of N-X bonds in the synthesis of N-heterocycles

Simple nitrogen-containing heterocycles could be constructed from carbon-carbon double bond (including fulleren) as carbon resources.

Acc. Chem. Res. 200942, 1172

Application of carbon dioxide to organic synthesis

Application of carbon dioxide to organic synthesis

Carbon dioxide fixation to unsaturated alcohols could be realized under extremely mild conditions by using tert-BuOI.

Angew. Chem. Int. Ed. 2010, 49, 1309.

Haloamidation of olefins induced by carbon dioxide was developed.

Org. Lett. 2006, 8, 967. Org. Bio.mol. Chem. 2010, 8, 1424

Application of water/silica system to organic synthesis

Application of water/silica system to organic synthesis

Organic reactions on silica in water were successfully achieved by utilizing hydrophobic interaction.

Chem. Rev. 2009109, 711. Angew. Chem. Int. Ed. 200443, 79

Saturday, 10 January 2015

(R)-(−)-2-[(5-oxido-5-phenyl-5λ4-isoquino[4,3-c][2,1]benzothiazin- 12-yl)amino]benzonitrile

abstract graphic

(R)-(−)-2-[(5-oxido-5-phenyl-5λ4-isoquino[4,3-c][2,1]benzothiazin- 12-yl)amino]benzonitrile (4).

Copper-catalyzed cross-coupling between (S)-S-methyl-S-phenylsulfoximine (1) and 2-iodobenzonitrile (2) resulted in the discovery of an unprecedented one-pot triple arylation sequence to give (R)-(−)-2-[(5-oxido-5-phenyl-5λ4-isoquino[4,3-c][2,1]benzothiazin- 12-yl)amino]benzonitrile (4). Here, we describe the synthesis of the title compound (R)-4 and the elucidation of its structure by means of various techniques.

Molbank 20142014(3), M834; doi:10.3390/M834


* Author to whom correspondence should be addressed; E-Mail:;
Fax: +29-241-80-92-391.
Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany

 Carsten Bolm

   Dr. rer. nat., Professor of Organic Chemistry
Institut für Organische Chemie
RWTH Aachen University
Landoltweg 1
D-52074 Aachen, Germany 
Tel.: + 49 241-80 94 675
FAX : + 49 241-80 92 391 

The combined organic phases were dried with
MgSO4 and filtered. After evaporation of solvents, the oily residue was subjected to column
chromatography (SiO2, n-pentane/EtOAc = 2/1). Product (R)-4 was isolated as a yellow solid.
Additionally, sulfoximine (S)-3 was separately obtained as a yellow oil (61% yield, 0.899 g, 3.51 mmol).
Yield: 23% (0.616 g, 1.34 mmol); mp = 211–212 °C (racemate: 263–265 °C); [α] = −57.7 (c = 0.6 g,
100 mL−1, CHCl3); 1H NMR (600 MHz, CDCl3): δ = 7.11 (ddd, J = 8.2 Hz, 7.1 Hz, 1.2 Hz, 1H, Ar-H),
7.25 (dd, J = 8.0 Hz, 1.1 Hz, 1H, Ar-H), 7.27 (td, J = 7.6 Hz, 1.0 Hz, 1H, Ar-H), 7.42–7.50 (m, 3H,
Ar-H), 7.50–7.58 (m, 3H, Ar-H), 7.70 (dd, J = 7.8 Hz, 1.5 Hz, 1H, Ar-H), 7.78 (ddd, J = 8.8 Hz, 7.5
Hz, 1.6 Hz, 1H, Ar-H), 7.87–7.90 (m, 2H, Ar-H), 8.07 (dd, J = 7.6 Hz, 1.6 Hz, 1H, Ar-H), 8.19–8.24
(m, 2H, Ar-H and NH), 8.50 (dd, J = 8.1 Hz, 1.5 Hz, 1H, Ar-H), 8.81 (d, J = 8.4 Hz, 1H, Ar-H) ppm;
13C NMR (150 MHz, CDCl3): δ = 103.4 (C), 105.5 (Ar-C), 116.9 (Ar-C), 117.5 (C), 118.4 (Ar-C),
120.3 (Ar-CH), 121.8 (Ar-CH), 122.3 (Ar-CH), 123.6 (Ar-CH), 123.8 (Ar-CH), 124.8 (Ar-CH), 125.9
(Ar-CH), 127.6 (Ar-CH), 127.7 (2 Ar-CH), 129.0 (2 Ar-CH), 132.0 (2 Ar-CH), 132.4 (Ar-CH), 132.5
(Ar-C), 132.8 (Ar-CH), 133.9 (Ar-CH), 141.7 (Ar-C), 144.0 (Ar-C), 144.2 (Ar-C), 148.0 (C), 153.2
(C) ppm; 1
H NMR [600 MHz, (CD3)2SO]: δ = 6.98 (ddd, J = 8.2 Hz, 7.2 Hz, 1.1 Hz, 1H, Ar-H), 7.11
(dd, J = 8.1 Hz, 0.8 Hz, 1H, Ar-H), 7.40 (ddd, J = 8.6 Hz, 7.2 Hz, 1.6 Hz, 1H, Ar-H), 7.53 (td, J = 7.7 Hz,
1.0 Hz, 1H, Ar-H), 7.56–7.60 (m, 2H, Ar-H), 7.60–7.64 (m, 1H, Ar-H), 7.67–7.73 (m, 2H, Ar-H), 7.80
(d, J = 8.0 Hz, 1H, Ar-H), 7.84–7.88 (m, 3H, Ar-H), 8.04 (dd, J = 7.8 Hz, 1.4 Hz, 1H, Ar-H), 8.12 (dd,
J = 7.7 Hz, 1.8 Hz, 1H, Ar-H), 8.18 (dd, J = 8.1 Hz, 1.5 Hz, 1H, Ar-H), 8.68 (dd, J = 7.5 Hz, 1.7 Hz,
1H, Ar-H), 10.51 (s, 1H, NH) ppm; 

13C NMR [150 MHz, (CD3)2SO]: δ = 103.5 (C), 110.2 (Ar-C),
117.0 (Ar-C), 117.4 (C), 118.0 (Ar-C), 119.7 (Ar-CH), 122.6 (Ar-CH), 123.6 (Ar-CH), 124.5 (Ar-CH),
125.6 (Ar-CH), 126.2 (Ar-CH), 127.1 (2 Ar-CH), 127.3 (Ar-CH), 127.4 (Ar-CH), 129.3 (2 Ar-CH), 
131.7 (Ar-C), 131.8 (Ar-CH), 132.2 (Ar-CH), 133.0 (Ar-CH), 133.1 (Ar-CH), 133.9 (Ar-CH), 141.9
(Ar-C), 143.7 (Ar-C), 144.0 (Ar-C), 147.4 (C), 155.6 (C) ppm; 

IR (ATR): ν = 3640, 3258, 2324, 2221,
2020, 1980, 1936, 1601, 1572, 1546, 1515, 1484, 1459, 1422, 1376, 1333, 1277, 1241, 1206, 1149,
1092, 1038, 1009, 976, 844, 794, 754, 720, 681 cm−1; EI-MS: m/z (%) = 458 (100) [M]+, 410 (15), 381(22), 357 (9), 333 (62), 102 (6), 77 (12), 51 (10); CI-MS: m/z (%) = 499 (3) [M+C3H5]+, 487 (16)[M+C2H5]+
, 459 (100) [M+H]+, 358 (7); ESI-MS: m/z (%) = 939 (9) [2M+Na]+, 497 (8) [M+K]+, 481(24) [M+Na]+, 459 (42) [M+H]+, 358 (100); ESI-HRMS: m/z calcd for C28H19N4OS: 459.12741; found
459.12793 with ∆ = 1.14 ppm; anal. calcd for C28H18N4OS (458.54): C, 73.34; H, 3.96; N, 12.22;
found C, 73.44; H, 4.09; N, 12.30; HPLC: tr = 16.8 min [major], tr = 25.2 min [minor] (Chiralpak AD-H,
0.6 mL min−1, n-heptane/isopropanol = 60/40, λ = 230 nm, 20 °C); >99% ee.
Crystallographic data were collected with a Bruker Kappa APEX II CCD-diffractometer with
monochromatic Mo–Kα radiation (λ = 0.71073 Å) and a CCD detector. The structure was solved by
direct methods using SHELXS-97 and refined against F2 on all data by full-matrix least-squares
methods using SHELXL-97 [13,14]. 

Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany


Tuesday, 6 January 2015

The rice flavor compound.......2-Acetyl-1-pyrroline

  • Skeletal formula of 2-acetyl-1-pyrroline


    2-Acetyl-1-pyrroline, abbreviated 2AP, with the IUPAC name 1-(3,4-dihydro-2H-pyrrol-5-yl)ethanone, is an aroma compound and flavor that gives white bread, jasmine rice and basmati rice, the spice pandan (Pandanus amaryllifolius), and bread flowers (Vallaris glabra) their customary smell.[1] 2-Acetyl-1-pyrroline and its structural homolog, 6-acetyl-2,3,4,5-tetrahydropyridine of similar smell, can be formed by Maillard reactions during heating of food such as the baking of bread dough. Both compounds have odor thresholds below 0.06 ng/l.[2]
    A pyrroline that is 1-pyrroline in which the hydrogen at position 2 is replaced by an acetyl group. It is an aroma and flavour compound present in jasmine rice and basmati rice. It is responsible for the 'popcorn' aroma in a large variety of cereal and food products. It is one of the key odourants of the crust of bread and considered to be responsible for the cracker-like odour properties. In bread, it is primarily generated during baking but amounts are influenced by ingredient composition and fermentation conditions.

    Structure and properties

    2-Acetyl-1-pyrroline is a substituted pyrroline and a cyclic imine as well as a ketone.

    The analogous 2-acetyl-1-pyrroline 6 has a similar potent cracker-like flavor and is considered as the most important flavor component of cooked rice. It has been identified and isolated from different varieties of cooked rice [R.G. Buttery, L.C. Ling, B.O. Juliano, Chem. Ind., 958 (1982); R.G. Buttery, L.C. Ling, B.O. Juliano, J.G. Turnbaugh, J. Agric. Food Chem., vol.31, 823 (1983); R.G. Buttery, L.C. Ling, T.R. Mon, J. Agric. Food Chem., vol.34, 112 (1986)] and the crust of wheat and rye bread [P. Schieberle, W. Grosch, J. Agric. Food Chem., vol.35, 252 (1987); P. Schieberle, w. Grosch, Z. Lebensm. Unters Forsch., vol. 180, 474 (1985)]. It is remarkable that 2-acetyl-1-pyrroline 6 has been found in pandam leaves (Pandanus amaryllifolius Roxb.)[R.G. Buttery, B.O. Juliano, L.C. Ling, Chem. Ind., 478 (1983)]. This fact explains that it has long been the practice in India and other parts of Asia to use leaves of Pandanus species in the cooking of common rices to impart a resemblance of the aroma of the more costly scented rice.
  • [0007]
    U.S. Pat. 4,522,838 discloses the sole known synthetic route to 2-acetyl-1-pyrroline.
  • [0008]
    The synthesis entails hydrogenation of 2-acetylpyrrole 4 with rhodium on alumina, followed by oxidation of the resulting aminoalcohol 5 by means of an excess of silver carbonate (absorbed on celite) in benzene.

    2-Acetyl-1-pyrroline 6 has been used in flavoring foods, particularly in imparting a scented rice flavor to foods. The drawback of this synthesis of the rice flavor component 6 is the use of the very expensive reagents, the low overall yield of 10%, the use of toxic chemicals (e.g. benzene) and the virtually inaccessibility of the compound on a larger scale. Indeed, according to the patented procedure mentioned above, 2-acetyl-1-pyrroline 6 was isolated and purified by preparative gas chromatography, which entails at best subgram quantities.

    • B.3. Synthesis of 2-Acetyl-1-pyrroline 6
    • [0021]
      The rice flavor compound 6 was prepared in exactly the same way as described in detail for the synthesis of the bread flavor component 3 (see A.3.). Compound 6 was obtained as a clear light-yellow oil (purity ⋟ 96%) which darkened rapidly on standing at room temperature in neat form (yield 40%). Compound 6 was characterized by the usual spectrometric methods (¹H NMR,¹³C NMR, IR, MS). It should be stressed that, contrary to compound 3, the rice flavor component 6 exclusively occurs as the imine form. The compound is preferably kept in dilute solution (pentane, dichloromethane) at -20°C. After an inital decantation from a small amount of dark viscous liquid (one week at -20°C), the clear solution is stable for several months at -20°C (up to now, we observed a good stability over a period of two years). 



    1. S. Wongpornchai, T. Sriseadka, S. Choonvisase (2003). "Identification and quantitation of the rice aroma compound, 2-acetyl-1-pyrroline, in bread flowers (Vallaris glabra Ktze)". J. Agric. Food. Chem. 51 (2): 457–462. doi:10.1021/jf025856x. PMID 12517110.
    2. T. J. Harrison, G. R. Dake (2005). "An expeditious, high-yielding construction of the food aroma compounds 6-acetyl-1,2,3,4-tetrahydropyridine and 2-acetyl-1-pyrroline". J. Org. Chem. 70 (26): 10872–10874. doi:10.1021/jo051940a. PMID 16356012.

    Yang DongSik, Lee Kyu‐Seong, Kays StanleyJ (2010)
    Characterization and discrimination of premium‐quality, waxy, and black‐pigmented rice based on odor‐active compounds
    Journal of the science of food and agriculture 90, 2595-2601 [Agricola:IND44456134]
    [show Abstract]
    Wongpornchai S, Sriseadka T, Choonvisase S (2003)
    Identification and quantitation of the rice aroma compound, 2-acetyl-1-pyrroline, in bread flowers (Vallaris glabra Ktze).
    Journal of agricultural and food chemistry 51, 457-462 [PubMed:12517110]
    [show Abstract]
    Costello PJ, Henschke PA (2002)
    Mousy off-flavor of wine: precursors and biosynthesis of the causative N-heterocycles 2-ethyltetrahydropyridine, 2-acetyltetrahydropyridine, and 2-acetyl-1-pyrroline by Lactobacillus hilgardii DSM 20176.
    Journal of agricultural and food chemistry 50, 7079-7087 [PubMed:12428963]
    [show Abstract]
    Maraval I, Sen K, Agrebi A, Menut C, Morere A, Boulanger R, Gay F, Mestres C, Gunata Z (2010)
    Quantification of 2-acetyl-1-pyrroline in rice by stable isotope dilution assay through headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry.
    Analytica chimica acta 675, 148-155 [PubMed:20800726]
    [show Abstract]
    Arikit S, Yoshihashi T, Wanchana S, Uyen TT, Huong NT, Wongpornchai S, Vanavichit A (2011)
    Deficiency in the amino aldehyde dehydrogenase encoded by GmAMADH2, the homologue of rice Os2AP, enhances 2-acetyl-1-pyrroline biosynthesis in soybeans (Glycine max L.).
    Plant biotechnology journal 9, 75-87 [PubMed:20497370]
    [show Abstract]
    Poonlaphdecha J, Maraval I, Roques S, Audebert A, Boulanger R, Bry X, Gunata Z (2012)
    Effect of timing and duration of salt treatment during growth of a fragrant rice variety on yield and 2-acetyl-1-pyrroline, proline, and GABA Levels.
    Journal of agricultural and food chemistry 60, 3824-3830 [PubMed:22404867]
    [show Abstract]
    Harrison TJ, Dake GR (2005)
    An expeditious, high-yielding construction of the food aroma compounds 6-acetyl-1,2,3,4-tetrahydropyridine and 2-acetyl-1-pyrroline.
    The Journal of organic chemistry 70, 10872-10874 [PubMed:16356012]
    [show Abstract]
    Adams A, De Kimpe N (2006)
    Chemistry of 2-acetyl-1-pyrroline, 6-acetyl-1,2,3,4-tetrahydropyridine, 2-acetyl-2-thiazoline, and 5-acetyl-2,3-dihydro-4H-thiazine: extraordinary Maillard flavor compounds.
    Chemical reviews 106, 2299-2319 [PubMed:16771451]

Monday, 5 January 2015

A Method to Identify Best Available Technologies (BAT) for Hydrogenation Reactors in the Pharmaceutical Industry

J. Flow Chem. 2012, 2(3), 77–82
Journal of Flow Chemistry
PublisherAkadémiai Kiadó
ISSN2062-249X (Print)
2063-0212 (Online)
SubjectFlow Chemistry
IssueVolume 2, Number 3/September 2012
Tuong Doan1, Petr Stavárek1, Claude Bellefon1 Email for* Author for correspondence:
1CNRS, CPE Lyon University of Lyon Villeurbanne France


A methodology that may be applied to help in the choice of a continuous reactor is proposed. In this methodology, the chemistry is first described through the use of eight simple criteria (rate, thermicity, deactivation, solubility, conversion, selectivity, viscosity, and catalyst). Then, each reactor type is also analyzed from their capability to answer each of these criteria. A final score is presented using “spider diagrams.” Lower surfaces indicate the best reactor choice. The methodology is exemplified with a model substrate nitrobenzene and a target pharmaceutical intermediate, N-methyl-4-nitrobenzenemethanesulphonamide, and for three different continuous reactors, i.e., stirred tank, fixed bed, and an advanced microstructured reactor. Comparison with the traditional batch reactor is also provided.