Letters in Organic Chemistry

ISSN: 1570-1786

Letters in Organic Chemistry
Volume 6, Number 6, September 2009


Contents


Diastereoselective Addition of Organometallic Reagents to Diimines Derived from (R,R)-1,2-Diaminocyclohexane and Aromatic Aldehydes Pp. 434-438
Diego Savoia, Andrea Gualandi and Marco Bandini
[Abstract] [Purchase Article]


A Reverse Wittig Coupling with Trifluoroacetaldehyde: A Convenient One-Step Synthesis of Trifluoromethyl Alkenes Pp. 439-443
Shainaz M. Landge, Dmitry A. Borkin and Béla Török
[Abstract] [Purchase Article]


Selective Synthesis of Unsaturated N-Acylethanolamines by Lipase-Catalyzed N-Acylation of Ethanolamine with Unsaturated Fatty Acids Pp. 444-447
Pierluigi Plastina, Jocelijn Meijerink, Jean-Paul Vincken, Harry Gruppen, Renger Witkamp and Bartolo Gabriele
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Investigation of the Effect of the Ligand/Palladium Ratio on the Catalytic Activity of Reusable Palladium/Phosphine/Ionic Liquid Systems in Aminocarbonylation of 17-iodo-androst-16-ene with Amino Acid Ester Nucleophile Pp. 448-452
Eszter Takács and Rita Skoda-Földes
[Abstract] [Purchase Article]


Synthesis of Oxathiocine Derivatives by Palladium-Catalyzed Intramolecular Heck Reaction Pp. 453-455
K.C. Majumdar, Buddhadeb Chattopadhyay and Biswajit Sinha
[Abstract] [Purchase Article]


High Stereoselective Mannich Reaction Catalyzed by Starch Sulfonic Acid in Water Pp. 456-461
Yu Wan, Wei Lin, Xiu-Mei Chen, Yang Shen, Hai-Qiang Xin, Hua-Hong Xu, Rui Yuan, Li-Ling Pang, Rui Ma, Cai-Hui Yue, Wei Yin, Rong-Cheng Bo and Hui Wu
[Abstract] [Purchase Article]


Synthesis of New Functionalized 2-Alkylsulfanyl-5-(1H-indol-2-yl)-1,3,4-Oxadiazole and a Facile Thio-Aza-Claisen Rearrangement of the S-Allyl Analog Pp. 462-469
El Sayed H. El Ashry, El Sayed H. El Tamany, Mohy El Din Abd El Fattah, Mohamed R.E. Aly and Ahmed T.A. Boraei
[Abstract] [Purchase Article]


Silica Sulfuric Acid as a Recyclable Catalyst for a One-Pot Synthesis of α-Aminophosphonates in Solvent-Free Conditions Pp. 470-473
Jing-Jun Yang, Jin-Ning Dang, Yu-Wei Chang
[Abstract] [Purchase Article]


The Efficient Synthesis of Dithieno[3,4-b:3',4'-d]thiophene Pp. 474-477
Li Xu, Zhen Wang, Kun Xu, Jianwu Shi and Hua Wang
[Abstract] [Purchase Article]


A Simple and Efficient Synthesis of 1,4- and 1,5-Dioxepan-2-one Pp. 478-480
Ali Hassannia, Graeme Piercy and Nabyl Merbouh
[Abstract] [Purchase Article]


Phosphonium Ionic Liquid Catalyzed an Efficient Synthesis of Chalcones Pp. 481-484
Swapnil R. Sarda, Wamanrao N. Jadhav, Sunil U. Tekale, Govind V. Jadhav, Bhagwan R. Patil, Gajanan S. Suryawanshi and Rajendra P. Pawar
[Abstract] [Purchase Article]


Synthesis of Poly(Phenylene Ethynylene)s Containing Trialkoxysilane Side Chains Pp. 485-490
Vikalp Thakor, Mahuya Bagui and Zhonghua Peng
[Abstract] [Purchase Article]


Development of Privileged Groebke-Blackburn-Type 4-(3-aminoimidazo [1,2-α]pyridin-2-yl)benzoic Acid Core into a Combinatorial Library on Solid Phase Pp. 491-495
Yuri Sandulenko, Alexander Komarov and Mikhail Krasavin
[Abstract] [Purchase Article]


A New, Efficient Entry to Non-Lipophilic H-Phosphonate Monoesters – Preparation of Anti-HIV Nucleotide Analogues Pp. 496-499
Joanna Romanowska, Agnieszka Szymańska-Michalak, Małgorzata Pietkiewicz, Michał Sobkowski, Jerzy Boryski, Jacek Stawiński and Adam Kraszewski
[Abstract] [Purchase Article]


Preparation and In Vitro Evaluation of Monoquaternary Inhibitors of Brain Cholinesterases Pp. 500-503
Daniel Jun, Martin Paar, Jiri Binder, Jan Marek, Miroslav Pohanka, Petr Stodulka and Kamil Kuca
[Abstract] [Purchase Article]


Influence of the Gas Atmosphere on the Deprotection of (Z)-γ-Hydroxy-α,β-Unsaturated Esters Pp. 504-506
Irakusne López, Santiago Rodríguez, Javier Izquierdo, Florenci V. González and Cristian Vicent
[Abstract] [Purchase Article]


Tandem Isomerization-Mannich Reactions from Allylic Alcohols and their Use for the Preparation of Four Diastereoisomers of 1-Amino-2-Methyl-1-Phenyloctan-3-ol Pp. 507-510
Hai T. Cao, Thierry Roisnel and René Grée
[Abstract] [Purchase Article]


A Convenient Synthesis of 1-Alkyl-7-chloro-6-fluoro-3-nitro-4-quinolones Pp. 511-514
Raed A. Al-Qawasmeh, Jalal A. Zahra, Monther A. Khanfar, Yusuf M. AL-Hiari, Mustafa M. El-Abadelah and Wolfgang Voelter
[Abstract] [Purchase Article]




Abstracts


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Diastereoselective Addition of Organometallic Reagents to Diimines Derived from (R,R)-1,2-Diaminocyclohexane and Aromatic Aldehydes
Diego Savoia, Andrea Gualandi and Marco Bandini

The double addition of organolithium compounds and allylzinc bromide to the imines prepared from (R,R)-1,2-diaminocyclohexane by condensation with aromatic and heteroaromatic aldehydes gave secondary diamines with high yields and diastereoselectivities apart for the reaction of 2-pyridinealdehyde derivative which occurred with low to moderate stereocontrol.


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A Reverse Wittig Coupling with Trifluoroacetaldehyde: A Convenient One-Step Synthesis of Trifluoromethyl Alkenes
Shainaz M. Landge, Dmitry A. Borkin and Béla

A novel, mild synthesis of aryl-3,3,3-trifluoropropenes by Wittig olefination of benzylphosphonium ylides with in-situ generated trifluoroacetaldehyde is described. The in-situ formed trifluoroacetaldehyde efficiently traps the Wittig ylides and yields trifluoromethyl alkenes without the troublesome handling. The scope of the reaction was tested in reaction of trifluoroacetaldehyde with a wide variety of benzylphosphonium ylides. The α-trifluoromethyl alkenes were isolated in good to excellent yields in a convenient one step process.


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Selective Synthesis of Unsaturated N-Acylethanolamines by Lipase-Catalyzed N-Acylation of Ethanolamine with Unsaturated Fatty Acids
Pierluigi Plastina, Jocelijn Meijerink, Jean-Paul Vincken, Harry Gruppen, Renger Witkamp and Bartolo Gabriele

The selective synthesis of unsaturated N-acylethanolamines 1b-6b by lipase-catalyzed direct condensation between unsaturated fatty acids 1a-6a and ethanolamine is reported. Reactions were carried out in hexane at 40 °C, in the presence of Candida antarctica Lipase B as the catalyst, to give the corresponding amides 1b-6b with yields ranging from 80 to 88%.


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Investigation of the Effect of the Ligand/Palladium Ratio on the Catalytic Activity of Reusable Palladium/Phosphine/Ionic Liquid Systems in Aminocarbonylation of 17-iodo-androst-16-ene with Amino Acid Ester Nucleophile
Eszter Takács and Rita Skoda-Földes

Ionic liquids as solvents were used effectively in palladium catalysed aminocarbonylation of 17-iodo-5α-androst-16-ene (1) with L-amino acid esters. Interestingly, optimal conditions that are essential for the successful reuse of the ionic liquid/catalyst mixture differ greatly from those observed in the similar reaction with simple secondary amines as nucleophiles.


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Synthesis of Oxathiocine Derivatives by Palladium-Catalyzed Intramolecular Heck Reaction
K.C. Majumdar, Buddhadeb Chattopadhyay and Biswajit Sinha

A novel approach towards the synthesis of hitherto unreported oxathiocine derivatives has been described by utilizing palladium-catalyzed intramolecular Heck reaction starting from deactivated allylic compounds.


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High Stereoselective Mannich Reaction Catalyzed by Starch Sulfonic Acid in Water
Yu Wan, Wei Lin, Xiu-Mei Chen, Yang Shen, Hai-Qiang Xin, Hua-Hong Xu, Rui Yuan, Li-Ling Pang, Rui Ma, Cai-Hui Yue, Wei Yin, Rong-Cheng Bo and Hui Wu

Starch sulfonic acid was used as efficient and highly stereoselective catalyst for the three-component Mannich reaction of aldehydes, amines, and ketones in water at ambient temperature to afford the corresponding β-amino ketones in good to excellent stereoselectivity and yields.


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Synthesis of New Functionalized 2-Alkylsulfanyl-5-(1H-indol-2-yl)-1,3,4-Oxadiazole and a Facile Thio-Aza-Claisen Rearrangement of the S-Allyl Analog
El Sayed H. El Ashry, El Sayed H. El Tamany, Mohy El Din Abd El Fattah, Mohamed R.E. Aly and Ahmed T.A. Boraei

The S-alkylated indolyloxadiazoles 2a-l were obtained regioselectively by alkylation of 5-(1H-indol-2-yl)-1,3,4-oxadiazole-2(3H)-thione 1, using TEA as acid scavenger. Alkylation of 1 with 1-bromopropane, 1-bromobutane, 1-bromoundecan, in the presence of K₂CO₃, yielded the N-alkylated products 3i-j,m in addition to the S-alkylated analogs 2i-j,m.

A facile thio-aza-Claisen rearrangement (S→N allylic rearrangement) of the S-allyl-oxadiazole 2k to the N-allyl analog 3k was achieved in excellent yield. Further allylation of 2k and 3k in the presence of K₂CO₃ led to allylation of the NH indole ring producing 5 and 6, respectively. Benzylation of 1 in the presence of K₂CO₃ yielded 7 which resisted the S→N migration of the benzyl group. The ¹H NMR, ¹³C NMR and mass spectra confirmed the structures and differentiated between the N- and S-alkylated products.


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Silica Sulfuric Acid as a Recyclable Catalyst for a One-Pot Synthesis of α-Aminophosphonates in Solvent-Free Conditions
Jing-Jun Yang, Jin-Ning Dang, Yu-Wei Chang

A simple and efficient method has been developed for the synthesis of α-aminophosphonates by a one-pot three-component condensation of aldehydes, amines and diethyl phosphite in the presence of a catalytic amount of silica sulfuric acid under solvent-free reaction conditions. The major advantages of the present method are good yields, inexpensive, ecofriendly and reusable catalyst, short reaction times, mild and solvent-free reaction conditions.


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The Efficient Synthesis of Dithieno[3,4-b:3',4'-d]thiophene
Li Xu, Zhen Wang, Kun Xu, Jianwu Shi and Hua Wang

The efficient synthesis of dithieno[3,4-b:3',4'-d]thiophene was improved by the introduction of TMS groups in four synthetic steps including TMS protection, sulfidation, intramolecular cyclization, and TMS removal. The total yield is 55-63% with 3,4-dibromothiophene as starting material. In addition, the crystal structure of (TMS)₄-dithieno[3,4-b:3',4'-d]thiophene was described.


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A Simple and Efficient Synthesis of 1,4- and 1,5-Dioxepan-2-one
Ali Hassannia, Graeme Piercy and Nabyl Merbouh

A novel synthesis of 1,4- and 1,5-dioxepan-2-one lactones was achieved through the regioselective oxidation of 3-(2-hydroxyethoxy)propan-1-ol. Under basic conditions, when 3-(2-hydroxyethoxy)propan-1-ol was oxidized using oxoammonium salts, a quantitative oxidative esterification was observed, resulting in a regioselective lactone ring closure. This oxidation was tailored to afford 1,4-dioxepan-2-one in very good yield.


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Phosphonium Ionic Liquid Catalyzed an Efficient Synthesis of Chalcones
Swapnil R. Sarda, Wamanrao N. Jadhav, Sunil U. Tekale, Govind V. Jadhav, Bhagwan R. Patil, Gajanan S. Suryawanshi and Rajendra P. Pawar

A clean and efficient method for the synthesis of chalcones using phosphonium ionic liquid catalyst [PhosIL-Cl] has been described. The method provides several advantages, such as mild reaction conditions, simple work-up procedure, afford high yields and ecofriendly. In addition, the green solvent ionic liquid was recovered and reused several times in subsequent reactions.


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Synthesis of Poly(Phenylene Ethynylene)s Containing Trialkoxysilane Side Chains
Vikalp Thakor, Mahuya Bagui and Zhonghua Peng

New hybrid monomers and polymers consisting of rigid π-conjugated rods flanked with trialkoxylsilane side chains have been successfully synthesized. It has been shown that the monomer undergoes a sol-gel process to form transparent gels, from which the organic rods can be subsequently removed to produce nanoporous materials.


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Development of Privileged Groebke-Blackburn-Type 4-(3-aminoimidazo [1,2-α]pyridin-2-yl)benzoic Acid Core into a Combinatorial Library on Solid Phase
Yuri Sandulenko, Alexander Komarov and Mikhail Krasavin

A library of 4-(3-acyl- or carbamoylaminoimidazo[1,2-a]pyridin-2-yl)benzamides (8) was synthesized on solid phase. A suitably protected core acid (1) was synthesized in multigram quantity using previously published procedure and used as the acylating reagent for modifying a set of AMEBA resins. Subsequent liberation of the amino group (using a novel hydrazine procedure) and its acylation or carbamoylation provided, after cleavage, final products in higher chemical yields and purities compared to known protocols that include formation of the imidazo[1,2-a]pyridine core on solid support.


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A New, Efficient Entry to Non-Lipophilic H-Phosphonate Monoesters – Preparation of Anti-HIV Nucleotide Analogues
Joanna Romanowska, Agnieszka Szymańska-Michalak, Małgorzata Pietkiewicz, Michał Sobkowski, Jerzy Boryski, Jacek Stawiński and Adam Kraszewski

Crystalline ammonium (9H-fluoren-9-yl)methyl H-phosphonate was prepared by a new, simple method and it was used as the reagent of choice for the introduction of an H-phosphonate monoester functionality into non-lipophilic anti-HIV nucleoside analogues.


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Preparation and In Vitro Evaluation of Monoquaternary Inhibitors of Brain Cholinesterases
Daniel Jun, Martin Paar, Jiri Binder, Jan Marek, Miroslav Pohanka, Petr Stodulka and Kamil Kuca

Acetylcholinesterase inhibitors are currently of high interest due to the many reasons. Among them, Alzheimer's disease drugs are of great interest. In this study, eleven monoquaternary pyridinium salts substituted by different groups (electron donors and electron acceptors) in position four were prepared. Then, their anticholinesterase activity was tested. As observed, their IC50s ranged from 33 μM to 3981 μM. Moreover, probability of blood-brain barrier penetration was predicted.


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Influence of the Gas Atmosphere on the Deprotection of (Z)-γ-Hydroxy-α,β-Unsaturated Esters
Irakusne López, Santiago Rodríguez, Javier Izquierdo, Florenci V. González and Cristian Vicent

The deprotection of O-protected (Z)-α-methyl-γ-hydroxy-α,β-unsaturated ester 1 furnishes dimer 2 when the reaction is performed under a nitrogen atmosphere, while compound 3 forms when the reaction is performed under an oxygen atmosphere.


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Tandem Isomerization-Mannich Reactions from Allylic Alcohols and their Use for the Preparation of Four Diastereoisomers of 1-Amino-2-Methyl-1-Phenyloctan-3-ol
Hai T. Cao, Thierry Roisnel and René Grée

The tandem isomerization-Mannich reaction of octen-3-ol and benzylidene N-sulfonyl imine affords the corresponding β-aminoketones in good yields. Diastereoselective reduction, followed by the deprotection of the primary amine, gives the expected 1-amino-2-methyl-1-phenyloctan-3-ol derivatives in excellent yields and in diastereomerically pure forms.


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A Convenient Synthesis of 1-Alkyl-7-chloro-6-fluoro-3-nitro-4-quinolones
Raed A. Al-Qawasmeh, Jalal A. Zahra, Monther A. Khanfar, Yusuf M. AL-Hiari, Mustafa M. El-Abadelah and Wolfgang Voelter

A convenient one-pot synthesis of 1-alkyl-7-chloro-6-flouro-3-nitro-1,4-dihydro-4-quinolones is described via nitro-decarboxylation of the respective 4-oxo-1,4-dihydroquinoline-3-carboxylic acid precursors. Reduction of the former 3-nitroquinolones delivered the corresponding 3-aminoquinolones, envisaged as valuable synthons in drug research.