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Letters in Organic Chemistry
ISSN: 1570-1786
Letters in Organic Chemistry
Volume 7, Number 6, September 2010
Contents
Graphical
Abstracts Pp. i-v
Metal Triflates: Efficient Catalysts for Oxa-Pictet-Spengler Reaction Pp. 420-423
Benaissa Bouguerne, Christian Lherbet and Michel Baltas
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Enantioselective Michael Addition of 2-Nitropropane to Substituted
Chalcones and Chalcone Analogues Catalyzed by Chiral Crown
Ethers Incorporating an α-D-Glucose or an α-D-Mannose Unit Pp. 424-431
Attila Makó, Zsolt Rapi, László Drahos, Áron Szöllosy, György Keglevich
and Péter Bakó
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Understanding the High Reactivity of the Azomethine Ylides in [3 + 2]
Cycloaddition Reactions Pp. 432-439
Luis R. Domingo, Eduardo Chamorro and Patricia Pérez
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Article]
Selective 5-exo-trig Iodocyclization of N-tosyl-2-allylanilines in Water Pp. 440-443
Michalis Batistatos, Manolis A. Fousteris, Sotiris S. Nikolaropoulos, Jean Le Bras and Jacques Muzart
[Abstract] [Supplementary
Material] [Purchase
Article]
Facile Regioselective Synthesis of 3-amino-2-(2'-arylindanedionyl)
inden-ones from 2-aryl-2,2'-biindan-1,1',3,3'-tetrones and Solvent-
Dependent Keto-Enol Tautomerism in Enaminones Pp. 444-449
Suven Das, Roland Fröhlich and Animesh Pramanik
[Abstract] [Purchase
Article]
A Mild and Convenient Semi-Synthesis of Docetaxel from 10-Deacetyl
Baccatin III Pp. 450-452
Hui Zhou, Dahai Chen, Hongwei Gao and Qingeng Li
[Abstract] [Purchase
Article]
TDAE-Initiated Synthesis of Oxiranes in Heterocyclic Series:
Reaction of 2-(Dibromomethyl)quinoxaline with
α-Dicarbonyl Derivatives Pp. 453-456
Marc Montana, Thierry Terme and Patrice Vanelle
[Abstract] [Purchase
Article]
Editor’s
Choice
Stereoselective Formal Synthesis of (-)-Salicylihalamides A and B
Via Prins Cyclisation Pp. 457-460
J.S. Yadav, N. Venkateswar Rao, P. Purushothama Rao, M. Sridhar Reddy and A.R. Prasad
[Abstract] [Purchase
Article]
Novel Prolinamide Organocatalysts Based on Calix[4]arene Scaffold
for the Enantioselective Direct Aldol Reaction Pp. 461-466
Zheng-Yi Li, Cheng-Xi Lu, Guoli Huang, Jie-Jie Ma, Hongsheng Sun,
Leyong Wang and Yi Pan
[Abstract] [Supplementary
Material] [Purchase
Article]
One-Pot Four-Component Synthesis of 3-(1,3,4-Thiadiazol-2-ylamino)-3-arylpropanoates Pp. 467-471
Zheng Li, Yanbo Li, Hongfang Cai, Jun Xu and Jinghong Shi
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Synthesis of Pyrrolizidine Derivatives in Ionic Liquid [bmim] Br Pp. 472-474
Laleh Faraji, Hamid Arvinnezhad, Naghmeh Alikami and Khosrow Jadidi
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Article]
Ru(II)- and Ir(I) Catalyzed Hydrogen Peroxide Oxidation of
Hydroxamic Acids and their Subsequent Hetero
Diels-Alder Cycloadditions with Chiral N-Dienyl Lactams Pp. 475-478
Ahmad Fakhruddin, Kesiny Phomkeona, Abdel-Moneim Abu-Elfotoh, Kazutaka Shibatomi and Seiji Iwasa
[Abstract] [Purchase
Article]
Regioselective Synthesis of Functionalized Oxime Ethers Pp. 479-482
Jun Liu, Dafeng Li, Jian Li, Chunju Li and Xueshun Jia
[Abstract] [Purchase
Article]
One-Pot Synthesis of Enaminones Using Gold's Reagent Pp. 483-486
Tamer S. Saleh, Mohamed A. Al-Omar and Hatem A. Abdel-Aziz
[Abstract] [Purchase
Article]
Novel dihydropyrazole Derivatives Linked with 4H-Chromene:
Microwave-Promoted Synthesis and Antibacterial Activity Pp. 487-490
Xin-Hua Liu, Jin-Xin Liu, Lin-Shan Bai, Guo-Lin Lan and Chu-Xiou Pan
[Abstract] [Purchase
Article]
H2O2/Phosphonium Ionic Liquid: An Efficient and Simple Approach for Benzyl Halides Oxidation Pp. 491-494
Satish A. Dake, Ravibhushan S. Kulkarni, Ambadas B. Rode, Pravin S. Shinde, Sushil K. Ghumbre, Rupali L. Magar and Rajendra P. Pawar
[Abstract] [Purchase
Article]
Perylenebisimide-Based Colorimetric and Fluorescent Sensors for
Selective Detection of Anions Pp. 495-501
Peng Guo, Xiaoyu Su and Jingbo Lan
[Abstract] [Supplementary
Material] [Purchase
Article]
Abstracts
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Metal Triflates: Efficient Catalysts for Oxa-Pictet-Spengler Reaction
Benaissa Bouguerne, Christian Lherbet and Michel Baltas
A screening of different metal triflates as catalysts was performed to get isochromans through an oxa-Pictet-Spengler reaction. Good to high yields were obtained for various aliphatic or aromatic aldehydes and β-arylethanols. A mechanism involving catalysis by in situ liberated triflic acid to catalyse the isochroman ring formation is proposed.
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Enantioselective Michael Addition of 2-Nitropropane to Substituted
Chalcones and Chalcone Analogues Catalyzed by Chiral Crown
Ethers Incorporating an α-D-Glucose or an α-D-Mannose Unit
Attila Makó, Zsolt Rapi, László Drahos, Áron Szöllősy, György Keglevich and Péter Bakó
The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-D-glucopyranoside- (1) or –mannopyranoside (2) used as phase transfer catalysts in the Michael addition of 2-nitropropane to substituted chalcones and chalcone analogues resulted in a significant asymmetric induction. The type of substituent on the chalcone molecule was found to have a significant influence on both the chemical yield and the enantioselectivity of the reaction: 24 novel chiral Michael adducts were prepared in 14-68% ee. These ee values were somewhat lower than that experienced in the case of the unsubstituted chalcone (85% ee). In the series of chalcone analogues, the 1-naphthyl Michael adduct was formed in 87% ee. Using glucose-based crown ether 1, formation of the (+)-enantiomers was preferred, while applying mannose-based 2 as the catalyst, the (-)-enantiomers were in excess.
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Understanding the High Reactivity of the Azomethine Ylides in [3 + 2]
Cycloaddition Reactions
Luis R. Domingo, Eduardo Chamorro and Patricia Pérez
The electronic reorganization along the [3+2] cycloaddition (32CA) reaction of the simplest azomethine ylide (AY) with ethylene has been studied using the topological analysis of the ELF at the B3LYP/6-31G(d) level of theory. This 32CA reaction, which has a negligible barrier (1.2 kcal/mol), takes place through a synchronous concerted transition state structure. The analysis of the ELF stresses that the pseudo-diradical character of the AY is responsible for the large reactivity of this species. Only the two non-bonding electrons located at the terminal carbon atoms of the AY and the two π electrons of ethylene are involved in this 32CA reaction. This cycloaddition, certainly not a pericyclic electron reorganization, may be electronically classified as [2n + 2π] process.
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Selective 5-exo-trig Iodocyclization of N-tosyl-2-allylanilines in Water
Michalis Batistatos, Manolis A. Fousteris, Sotiris S. Nikolaropoulos, Jean Le Bras and Jacques Muzart
[Supplementary
Material]
Various 2-iodomethyl-N-tosylindolines are obtained in high yields from the reaction of N-tosyl-2-allylanilines with iodine in water at 50 °C.
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Article]
Facile Regioselective Synthesis of 3-amino-2-(2′-arylindanedionyl)
inden-ones from 2-aryl-2,2′-biindan-1,1′,3,3′-tetrones and Solvent-
Dependent Keto-Enol Tautomerism in Enaminones
Suven Das, Roland Fröhlich and Animesh Pramanik
Refluxing 2-Aryl-2,2′-biindan-1,1′,3,3′-tetrones in acetic acid with urea produces 3-amino-2-(2′-arylindanedionyl)indenones regioselectively within 2-3 h. in good yields. X-ray crystal structures of the products clearly indicate that in the solid state the compounds exist in the keto form. On the other hand NMR studies reveal that the enaminones exist in keto form in CDCl3 and in enol form in DMSO-d6 and acetone-d6.
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Article]
A Mild and Convenient Semi-Synthesis of Docetaxel from 10-Deacetyl
Baccatin III
Hui Zhou, Dahai Chen, Hongwei Gao and Qingeng Li
A novel protocol for the semi-synthesis of docetaxel was achieved in four steps from 10-deacetyl baccatin III
with an overall yield of 50%. The key step is the selective protection of the C(7) and C(10) hydroxyl groups of 10-
deacetyl baccatin III, utilizing benzyl chloromate as a selective protecting reagent, which are capable of being
conveniently removed by Pd/C under hydrogen atmosphere.
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Article]
TDAE-Initiated Synthesis of Oxiranes in Heterocyclic Series:
Reaction of 2-(Dibromomethyl)quinoxaline with
α-Dicarbonyl Derivatives
Marc Montana, Thierry Terme and Patrice Vanelle
A new series of quinoxalinic oxirane derivatives was synthesized from reaction between 2-(dibromomethyl) quinoxaline and α-dicarbonyl compounds using tetrakis(dimethylamino)ethylene (TDAE).
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Article]
Stereoselective Formal Synthesis of (-)-Salicylihalamides A and B
Via Prins Cyclisation
J.S. Yadav, N. Venkateswar Rao, P. Purushothama Rao, M. Sridhar Reddy and A.R. Prasad
A stereoselective and convergent formal approach to Salicylihalamide A and B is achieved through our recently developed strategy for the construction of polyketide precursors via Prins cyclisation. The approach mainly relies upon reductive opening of 1-iodomethyl cyclic ethers, Mitsunobu inversion and ring closing metathesis along with Prins cyclisation.
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Article]
Novel Prolinamide Organocatalysts Based on Calix[4]arene Scaffold
for the Enantioselective Direct Aldol Reaction
Zheng-Yi Li, Cheng-Xi Lu, Guoli Huang, Jie-Jie Ma, Hongsheng Sun,
Leyong Wang and Yi Pan
[Supplementary
Material]
A series of novel prolinamide organocatalysts based on calix[4]arene scaffold have been developed to catalyze the direct asymmetric aldol reaction of aromatic aldehydes and cyclohexanone. Under the optimal condition, high isolated yields (up to > 99%) and enantioselectivities (up to 97% ee), and moderate diastereoselectivities (up to 85/15) were obtained
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Article]
One-Pot Four-Component Synthesis of 3-(1,3,4-Thiadiazol-2-ylamino)-3-arylpropanoates
Zheng Li, Yanbo Li, Hongfang Cai, Jun Xu and Jinghong Shi
A novel one-pot four-component synthetic method for 3-(1,3,4-thiadiazol-2-ylamino)-3-arylpropanoates by condensation of 2-amino-1,3,4-thiadiazoles, aldehydes, Meldrum’s acid and aliphatic alcohols catalyzed by p-toluenesulfonic acid was described. The protocol has advantages of mild conditions, high yield and simple work-up procedure.
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Article]
Synthesis of Pyrrolizidine Derivatives in Ionic Liquid [bmim] Br
Laleh Faraji, Hamid Arvinnezhad, Naghmeh Alikami and Khosrow Jadidi
Pyrrolizidines were synthesized from 1,3-dipolar cycloaddition of N-substituted isatins, proline, and olefins. The highly diastereoselective and regioselective one-pot three-component cyclocondensation products were obtained in the presence of ionic liquids such as 1-buthyl-3-methlylimidazolium bromide.
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Article]
Ru(II)- and Ir(I) Catalyzed Hydrogen Peroxide Oxidation of
Hydroxamic Acids and their Subsequent Hetero
Diels-Alder Cycloadditions with Chiral N-Dienyl Lactams
Ahmad Fakhruddin, Kesiny Phomkeona, Abdel-Moneim Abu-Elfotoh, Kazutaka Shibatomi and Seiji Iwasa
Asymmetric hetero Diels-Alder (HDA) reaction of highly reactive acyl nitroso intermediates are reported. Transient acyl nitroso compounds 2a’-c’ are formed by Ru(II)- or Ir(I)-catalyzed hydrogen peroxide oxidation of hydroxamic acids 2a-c and are trapped in situ by the optically pure N-dienyl-L-pyroglutamates 1a-b to afford the corresponding diastereomeric adducts 3a-f and 4a-f up to 98% yield (70% de) and 72% de (70% yield) with complete regioselectivity at 0 ˚C to room temperature.
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Regioselective Synthesis of Functionalized Oxime Ethers
Jun Liu, Dafeng Li, Jian Li, Chunju Li and Xueshun Jia
We report in this paper the regioselective synthesis of functionalized oxime ethers 3 in good yields from the reaction of readily available starting material oximes with allyl bromides, derived from Baylis-Hillman adducts, in the presence of sodium hydride and triethyl amine under mild condition.
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One-Pot Synthesis of Enaminones Using Gold's Reagent
Tamer S. Saleh, Mohamed A. Al-Omar and Hatem A. Abdel-Aziz
Enaminones were efficiently prepared via modification for Gupton method, which depends on carrying out the latter procedure in one step reaction, avoiding the isolation of [3-(dimethylamino)-2-azaprop-2-en-1-ylidene]dimethylammonium chloride (Gold's reagent) (5) which is prepared in situ from cyanuric chloride (4) then it reacts successfully with ketone 1a-j to produce the enaminones 3a-j in suitable yields. The modified method overcomes the drawbacks of the known methods for preparation of enaminones.
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Article]
Novel dihydropyrazole Derivatives Linked with 4H-Chromene:
Microwave-Promoted Synthesis and Antibacterial Activity
Xin-Hua Liu, Jin-Xin Liu, Lin-Shan Bai, Guo-Lin Lan and Chu-Xiou Pan
Seven novel 6-(1-acetyl-3-methyl-4,5-dihydro-1H-pyrazol-5-yl)-2-amino-4-substituted-phenyl-4H-chromene-3-carbonitrile derivatives were synthesized and characterized by ESI-MS, 1H NMR and 13C NMR. All of the compounds have been screened for their antibacterial activity. The results show that compounds 7e and 7f displayed significant activity with MIC of 1.562 μg/mL against B. subtilis ATCC 6633.
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H2O2/Phosphonium Ionic Liquid: An Efficient and Simple Approach for Benzyl Halides Oxidation
Satish A. Dake, Ravibhushan S. Kulkarni, Ambadas B. Rode, Pravin S. Shinde, Sushil K. Ghumbre, Rupali L. Magar and Rajendra P. Pawar
An efficient oxidation of benzyl halide has been done using aqueous hydrogen peroxide (30%) in trihexyl(tetradecyl)phosphonium-tetrafluroborate ionic liquid the protocol is simple mild offering excellent yield of product.
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Article]
Perylenebisimide-Based Colorimetric and Fluorescent Sensors for
Selective Detection of Anions
Peng Guo, Xiaoyu Su and Jingbo Lan
[Supplementary
Material]
A new type of perylenebisimide-based imidazolium chemosensor was synthesized for selective recognition of anions. Imidazolium-anchored receptor PBI-1 showed high binding affinity to F- due to the role of the phenolic hydroxyl group as an additional binding site. The hydroxyl-protected receptor PBI-2 could serve as highly selective and sensitive colorimetric and fluorometric sensor for H2PO4-. The study indicated that the C2-H of the imidazolium ring played an essential role in the anion recognition via synergistic effects of multiple hydrogen-bonding and electrostatic interactions. In addition, it was noteworthy that the phenolic hydroxy of the receptor was not indispensable for binding H2PO4-, but very pivotal for binding F-.
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