Letters in Organic Chemistry, Volume 2, No. 6, 2005

Contents

Modification of Nucleoside Heterocycles to Probe and Expand Nucleic Acid Structure and Function Pp.496-500

Eriks Rozners

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Letters in Organic Chemistry

2-Imidazolone Derivatives Obtained as Unexpected Products Throughout Imidazole N3-Oxide Rearrangement

(Supplementary Material Available)

H. Cerecetto, A. Gerpe, M. Gonzalez, O.E. Piro and E.E. Castellano

[Abstract] [Purchase Article]

An Effective Methodology to Novel Larger Imidazolium Cyclophanes Pp.507-511

Xia Wei, Jin Liu, Guo-lin Zhang, Zong-lin Jiang, Cheng-he Zhou, Kui Luo and Ru-gang Xie

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Diastereoselective Allylation of Imines with g–Silyloxyallylstannanes Promoted by Trimethylsilyl Triflate and Application to the Synthesis of Erythro-Sphingosine Pp.512-514

Makoto Shimizu, Hiromi Ando and Yasuki Niwa

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Introduction of a Benzoquinone Pharmacophore on a Labdane Platform Pp.515-517

Jamila Aslaoui and Christophe Morin

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Fluorine-Substituted Tetraphenylethene Systems Pp.518-520

Zakir Hussain, Henning Hopf and Thomas Oeser

[Abstract] [Purchase Article]

Efficient Chemical Synthesis of Sialic Acid Related Oligosaccharides Pp.521-523

C. Zhao, X. Zhen, H. Zhang and Y. Ding

[Abstract] [Purchase Article]

Enantioselective Nozaki-Hiyama Allylations Using a Multidentate Amino Alcohol as a Chiral Ligand Pp.524-527

Eriks Rozners and Juan Fontanez

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Synthesis of 14-Membered Ring Jaspamide Derivatives Pp.528-531

Sylvain Celanire, Carole Descamps-François, Brigitte Lesur, Gerald Guillaumet and Benoît Joseph

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First Microwave-Assisted Synthesis of 3-Substituted Isocoumarins Pp.532-534

Khalid Mohammed Khan, Sumbul Ahmed, Zulfiqar Ali Khan, Mubeen Rani, Shahnaz Perveen, M. Iqbal Choudhary and Atta-ur-Rahman

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Syntheses of Carbamate Derivatives of Quercetin by Reaction with Amino Acid Ester Isocyanates Pp.535-538

Xianxue Wu, Li Cheng, Dong Xiang and Yuquan Wei

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A Combined Theoretical and Experimental Approach to 2,3,2',3' Tetrahydro- 1H,1'H-[2,2']Biindenyl Pp.539-543

Zakir Hussain, Henning Hopf , Thomas Oeser and Joerg Grunenberg

[Abstract] [Purchase Article]

Chromium Trioxide Supported on NaHSO₄.H₂O: Simple Oxidation of Alcohols in Solution and Solvent free Conditions Pp.544-546

Farhad Shirini, Mohammad Ali Zolfigol and Shayesteh Torabi

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An Enantiomeric Synthesis of (+)-Gloeosporone Pp.547-549

Anubha Sharma, Sunita Gamre and Subrata Chattopadhyay

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Phosphonium Ionic Liquids as Solvents for Nitration Reactions of Arenes Pp.550-553

Bethany D. Powell, Gregory L. Powell and Perry C. Reeves

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Efficient Photocleavage of Lysozyme by a New Chiral Probe Pp.554-558

Apinya Buranaprapuk, Parin Chaivisuthangkura, Jisnuson Svasti and Challa V. Kumar

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Oxidation of Aromatic Alcohols to Carbonyl Compounds with Oxygen Catalyzed by Iron (III) Chloride Supported on Kieselguhr Pp.559-560

Mohammed M. Hashmi, Ali Ezabadi and Zahed Karimi-Jaberi

[Abstract] [Purchase Article]

One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Using ZnCl₂, CuCl₂, NiCl₂ and CoCl₂ Doped Hydroxyapatite Pp.561-565

Hanane El Badaoui, Fathallaah Bazi, Samira Sokori, Saïd Boulaajaj, Hassan B. Lazrek and Said Sebti

[Abstract] [Purchase Article]

Functionalized, Differently Fluorinated Building-Blocks Via Michael Addition of Enamines to g-Fluoro-a-Nitroalkenes Pp.566-568

Marco Molteni and Matteo Zanda

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A Facile Method for the Synthesis of Pyrazolyl and Pyrazolinyl Carbazoles Pp.569-572

Yusuf Zulykama, Rajagopal Nagarajan and Paramasivan T. Perumal

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Abstracts

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Modification of Nucleoside Heterocycles to Probe and Expand Nucleic Acid Structure and Function

Eriks Rozners

Recent progress in molecular biology and genetics has invigorated interest in modified nucleic acids both for fundamental studies and for practical applications. Herein, recent advances in design of modified non-Watson-Crick base pairs are highlighted. Examples of altered hydrogen-bonding patterns, size-expanded bases, and base pairing dependent on metal chelation and hydrophobic interactions are discussed.

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2-Imidazolone Derivatives Obtained as Unexpected Products Throughout Imidazole N3-Oxide Rearrangement (Supplementary Material Available)

H. Cerecetto, A. Gerpe, M. Gonzalez, O.E. Piro and E.E. Castellano

3-Alkyl(aryl)-2,3-dihydro-1H-2-imidazolone derivatives as unexpected product of the reaction between ethyl 3-alkyl(aryl)amino-2-oximinobutanoate and methyl orthoformate is described. These imidazolones are generated by an intramolecular attack and a migration of N³-oxide oxygen from the imidazole N³-oxide intermediates. This proposed mechanism is supported by the results of theoretical studies (DFT).

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An Effective Methodology to Novel Larger Imidazolium Cyclophanes

Xia Wei, Jin Liu, Guo-lin Zhang, Zong-lin Jiang, Cheng-he Zhou, Kui Luo and Ru-gang Xie

A type of novel larger imidazolium cyclophanes have been designed and synthesized by ingeniously employing intermediates with spacers. The tandem-MS has been employed to certify that the cyclophanes unarguably have symmetrical structures like calix[8]arene.

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Diastereoselective Allylation of Imines with g–Silyloxyallylstannanes Promoted by Trimethylsilyl Triflate and Application to the Synthesis of Erythro-Sphingosine

Makoto Shimizu, Hiromi Ando and Yasuki Niwa

Addition of g-silyloxyallylstannanes to imines in the presence of trimethylsilyl triflate was studied. Allylation of a-imino ester with (Z)-allylstannane proceeded to give anti-adduct as a major product, which was transformed into N,O,O-triacetyl erythro-sphingposine via appropriate functional group transformations.

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Introduction of a Benzoquinone Pharmacophore on a Labdane Platform

Jamila Aslaoui and Christophe Morin

The allylic alcohol of the side-chain of larixol was converted into an exo 1,3-diene through trifluoroacetylation followed by palladium-catalyzed elimination; this allowed the introduction of a benzoquinone pharmacophore on this labdane platform in ‘one-pot’ from allylic trifluoroacetates.

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Fluorine-Substituted Tetraphenylethene Systems

Zakir Hussain, Henning Hopf and Thomas Oeser

Synthesis of novel fluorinated tetraphenylethene systems 5a-c was carried out and resulting new materials were investigated for their mesomorphic properties. New materials (5a-c) were prepared by the esterification of 3 with either 4-trifluoromethoxybenzoic acid (5a), 3,4,5-trifluorobenzoic acid (5b), or 4-trifluoromethylbenzoic acid (5c). All compounds (5a-c) were fully characterized while stereochemical features of compound 5a were investigated by its single crystal X-ray analysis.

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Efficient Chemical Synthesis of Sialic Acid Related Oligosaccharides

C. Zhao, X. Zhen, H. Zhang and Y. Ding

A very efficient strategy for the chemical synthesis of the sialyl Lewis X tetrasaccharide is reported. Starting from four simple monosaccharide building blocks, sialyl Lewis X was obtained in seven steps. By using similar strategy, sialyl LacNAc and sulfated sialyl LacNAc trisaccharides were also synthesized.

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Enantioselective Nozaki-Hiyama Allylations Using a Multidentate Amino Alcohol as a Chiral Ligand

Eriks Rozners and Juan Fontanez

Asymmetric Nozaki-Hiyama allylations using a proline derived amino alcohol as a chiral ligand showed good enantioselectivity (er up to 90:10). The results suggest that efficient catalysts for this type of chromium-mediated reactions may be designed using multidentate ligands based on sp3 hybridized backbones.

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Synthesis of 14-Membered Ring Jaspamide Derivatives

Sylvain Celanire, Carole Descamps-Francois, Brigitte Lesur, Gerald Guillaumet and Benoit Joseph

Two synthetic approaches of simpler jaspamide derivatives were investigated. The ring closure step was attempted either by RCM or by macrolactonisation. 14-Membered ring derivatives 15-16 were prepared by final macrolactonisation using Yamaguchi reagent.

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First Microwave-Assisted Synthesis of 3-Substituted Isocoumarins

Khalid Mohammed Khan, Sumbul Ahmed, Zulfiqar Ali Khan, Mubeen Rani, Shahnaz Perveen, M. Iqbal Choudhary and Atta-ur-Rahman

A microwave-assisted, environment friendly, high yielding, time saving synthesis of medicinally important 3-substituted isocoumarins was carried out in a single step by the direct condensation of homophthalic acid with aryol and acyl chlorides under the solvent-free conditions without any solid support. The synthesized isocoumarins were structurally characterized by microanalysis, ¹H-NMR, EI, IR and UV.

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Syntheses of Carbamate Derivatives of Quercetin by Reaction with Amino Acid Ester Isocyanates

Xianxue Wu, Li Cheng, Dong Xiang and Yuquan Wei

Synthesis of amino acid carbamate derivatives of quercetin from partly protected quercetin and amino acid esters utilizing triphosgene as an auxiliary reagent was studied. A series of quercetin derivatives were obtained regioselectively by reaction with amino acid ester isocyanates under mild conditions and in high yields.

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A Combined Theoretical and Experimental Approach to 2,3,2',3' Tetrahydro- 1H,1'H-[2,2']Biindenyl

Zakir Hussain, Henning Hopf , Thomas Oeser and Joerg Grunenberg

Synthesis of 2,3,2',3'-tetrahydro-1H,1'H-[2,2']biindenyl 2 from the dimerization reaction of indene with lithium naphthalenide was carried out and we here report its single crystal X-ray structure. Synthesis and characterization of compounds 3-8 have also been carried out successfully. The stability of biindenyl and its stereochemistry at position 2 and 2' was investigated using density functional theory.

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Chromium Trioxide Supported on NaHSO₄.H₂O: Simple Oxidation of Alcohols in Solution and Solvent free Conditions

Farhad Shirini, Mohammad Ali Zolfigol and Shayesteh Torabi

Alcohols are conveniently converted to their corresponding carbonyl compounds with CrO₃ supported on NaHSO₄.H₂O in solution and under solvent free conditions.

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An Enantiomeric Synthesis of (+)-Gloeosporone

Anubha Sharma, Sunita Gamre and Subrata Chattopadhyay

A simple and facile synthesis of (+)-gloeosporone was developed using chirons that were available by lipase catalyzed acylation and chemical resolution.

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Phosphonium Ionic Liquids as Solvents for Nitration Reactions of Arenes

Bethany D. Powell, Gregory L. Powell and Perry C. Reeves

Commercially available tetraalkylphosphonium ionic liquids are effective as solvents in the mild nitration of various arenes and offer some advantages over the more common N, N-dialkylimidazolium ionic liquids.

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Efficient Photocleavage of Lysozyme by a New Chiral Probe

Apinya Buranaprapuk, Parin Chaivisuthangkura, Jisnuson Svasti and Challa V. Kumar

Photocleavage of lysozyme and bovine serum albumin (BSA) by L-phenylalanine-1(1-pyrene)methylamide (PMA-L-Phe) is reported here. The chiral probe, PMA-L-Phe, has a positively charged side chain, while the previous probes carried a free carboxyl group. The yield of lysozyme cleavage by PMA-L-Phe is increased to 57% when compared to the previous probes, while the yield of BSA cleavage is reduced to <5%. Sequencing studies indicated that PMA-L-Phe cleaves lysozyme at a single site, between residues Trp108-Val109. Absorption and fluorescence spectral data indicate that PMA-L-Phe binds to lysozyme and BSA with affinity constants (K_b) of 3.3x10⁵ M^-1 and 3.8x10⁵ M^-1, respectively.

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Oxidation of Aromatic Alcohols to Carbonyl Compounds with Oxygen Catalyzed by Iron (III) Chloride Supported on Kieselguhr

Mohammed M. Hashmi, Ali Ezabadi and Zahed Karimi-Jaberi

Oxidation of aromatic alcohols to corresponding aldehydes and ketones have been carried out using molecular oxygen and FeCl₃ supported on kieselguhr as catalyst in good yields.

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One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Using ZnCl₂, CuCl₂, NiCl₂ and CoCl₂ Doped Hydroxyapatite

Hanane El Badaoui, Fathallaah Bazi, Samira Sokori, Saïd Boulaajaj, Hassan B. Lazrek and Said Sebti

Hydroxyapatite doped with ZnCl₂, CuCl₂, NiCl₂ and CoCl₂ efficiently catalyses the three components Biginelli reaction between an aldehyde, ethyl acetoacetate and urea in refluxing toluene to afford the corresponding dihydropyrimidinones in high yields.

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Functionalized, Differently Fluorinated Building-Blocks Via Michael Addition of Enamines to g-Fluoro-a-Nitroalkenes

Marco Molteni and Matteo Zanda

The Michael addition of ketone-derived enamines to g-fluoro-a-nitroalkenes provides in moderate to good isolated yields the corresponding b-fluoroalkyl g-nitroketones, which can be reduced to b-fluoroalkyl g-nitroalcohols.

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A Facile Method for the Synthesis of Pyrazolyl and Pyrazolinyl Carbazoles

Yusuf Zulykama, Rajagopal Nagarajan and Paramasivan T. Perumal

Synthesis of pyrazolylcarbazoles and pyrazolinylcarbazoles is reported. Phenylhydrazones of acylcarbazoles furnished pyrazolylcarbazoles under Vilsmeier conditions. Carbazolylchalcones on treatment with hydrazine in acetic acid furnished pyrazolinylcarbazoles.