Letters in Organic Chemistry

ISSN: 1570-1786

Letters in Organic Chemistry
Volume 3, Number 3, March 2006

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Recent Trends in Enantioselective Diorganozinc-Additions to Aldehydes Pp. 176-182

Vladimir Dimitrov & Kalina Kostova In recent years, impressive progress has been made in the development of new chiral ligands and in new methodology for Znmediated enantioselective additions to aldehydes. The current report aims to present the recent progress in this field.

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Letters in Organic Chemistry

Hydroiodination of Terminal Double Bonds Via Hydroboration or Hydrozirconation in Connection with the Total Synthesis of Fluvirucins Pp. 183-186

Glòria Freixas, Fèlix Urpí & Jaume Vilarrasa Hydroboration and hydrozirconation of 4-pentenoic acid derivatives and of the 4-penten-1-ol derivative shown in the scheme, followed by their iodination in situ, have been systematically compared and practical improvements have been disclosed. The hydroboration–iodination procedure is recommendable for the pentenoic acid derivatives whereas the hydrozirconation–iodination protocol is the method of choice for the pentenol derivative.

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Synthesis of β-Amino Alcohols by Regioselective Ring Opening of Epoxides with Aromatic Amines Catalyzed by Tin (II) Chloride [1] Pp. 187-190

M. Mujahid Alam, Ravi Varala, Ramu Enugala & Srinivas R. Adapa Synthesis of β-Amino Alcohols by Regioselective Ring Opening of Epoxides with Aromatic Amines Catalyzed by Tin (II) Chloride.

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Solvent Dependent Benzylic Radical Bromination of Aromatic Sulfonyl Chlorides Pp. 191-194

Martina Gensini, Gianluca Battaglia, Rossano Nannicini, Annalisa Guerri, Maria Altamura & Laura Quartara An efficient method for the benzylic radical bromination of toluene sulfonyl chlorides has been developed. The use of a combination of NBS and Vazo 67® in CH3CN allows to obtain the desired bromoderivatives in a reproducible manner at different scale processes.

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Convenient Synthesis of Some New Substituted Pyrazolyl-1,3,4-Oxadiazoles and Pyrazolyl-1,2,4-Triazoles Pp. 195-200

Yehya M. Elkholy, Korany A. Ali & Ahmad M. Farag A simple and versatile method for the synthesis of pyrazol-3-yl-1,3,4-oxadiazole and pyrazol-3-yl-1,2,4-triazole derivatives from 1,5-diphenyl -1H-pyrazole-3-carboxylic acid hydrazide has been developed.

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Efficacious Preparation of Biginelli Compounds. A Comparative Study of Different Reaction Techniques Pp. 201-203

Kamaljit Singh, Sukhdeep Singh & Paramjit Kaur An ambient temperature ultrasound-assisted preparation of a series of dihydropyrimidinones under solvent-free conditions is described.

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Highly Wolff Selective Rh(II) Catalysed Decomposition of α-Diazo-β -Ketophosphonates Having an Oxygen Atom Adjacent to the γ-Position Pp. 204-206

Mohamed Boukraa, Wissam Dayoub & Alain Doutheau When submitted to the action of catalytic Rh(II) in refluxig toluene, α-diazo-β-ketophosphonates of type 1 gave rise to compounds mainly or exclusively derived from intermediate ketenes 2 resulting from a Wolff rearrangement. The presence of the electron withdrawing oxygen atom adjacent to the γ-position would prevent competing C-H reactions to occur.

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An Effective Chemoselective Esterification of Hydroxybenzoic Acids in Ionic Liquid Promoted by KF Pp. 207-211

Daniele Biondini, Lucia Brinchi, Raimondo Germani & Gianfranco Savelli Ionic liquid 1,3-dimethylimidazolium methanesulfonate has been used. as efficient medium for the chemoselective synthesis of benzylic, allylic and phenacylic esters of hydroxybenzoic acids using KF as promoting base.

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Reaction of 2-Diazo-1,2-diphenylethanone with 2-[(Arylimino)methyl]phenols Pp. 212-213

Tshepo Pheko& Girija S. Singh The regiochemistry of the titled reaction depends on the substitutent at N-phenyl ring.

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Synthesis of C7-Substituted Estra-1,3,5(10),6-Tetraen-3,17 β-Diols Pp. 214-219

Goreti Ribeiro Morais, Mª Cristina das Neves Oliveira & Thies Thiemann A series of C7-substituted estra-1,3,5(10),6-tetraen-3,17β-diols were prepared as precursors of radiodiagnostic agents for the detection of breast cancer. The introduction of the olefin moiety at C6/C7 in the molecules was achieved through thermal elimination of the 6-hydroxy group in the corresponding estra-1,3,5(10)-triene-3,6,17β-triols.

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Novel and Highly Selective Conversion of Alcohols , Thiols and Trimethylsilyl Ethers to Alkyl Nitrites with 2,4,6-Trichloro[1,3,5]triazine/n-Bu4NNO2 System Pp. 220-224

Batool Akhlaghinia & Elham Roohi Alkyl nitrites were prepared in good to excellent yields by treatment of alcohols, thiols and trimethylsilyl ethers with 2,4,6-trichloro[1,3,5] triazine/n-Bu4NNO2 in refluxing acetonitrile. This method is highly selective for the conversion of primary alcohols to alkyl nitrites in the presence of secondary and tertiary alcohols, thiols and trimethylsilyl ethers.

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One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Using Hydrochloric Acid-β-Cyclodextrin-Combined Catalysts Pp. 225-227

Haixia Zhou, Miao He, Chunsheng Liu & Genxiang Luo The synthesis of 3,4-dihydropyrimidin- 2(1H)-one derivatives with high yields was performed by using β-cyclodextrin and hydrochloric acid as an inexpensive and easily available catalyst.

Indium Triflate Catalysed Ene and Friedel Crafts Additions to α-Imino Esters: A One-Pot Synthesis of α-Amino Acid Derivatives Pp. 228-230

Kamlesh K. Chauhan, Joseph P. Hartley, Matthew Krakowski & Christopher G. Frost The indium catalysed additions of electron-rich alkenes and heteroaromatics to an activated α-amino ester is described. The moisture-sensitive substrate is prepared in situ facilitating a convenient synthesis of unnatural α-amino acid derivatives in onepot from commercially available reagents.

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Oxidation of Flavan-3-Ols: Gram-Scale Synthesis of Taxifolin Pp. 231-234

Nour-Eddine Es-Safi & Paul-Henri Ducrot Benzylic oxidation of catechine has been performed using either DDQ or Ce(IV) trifluoromethanesulfonate as oxidizing agent. These procedures allowed the efficient synthesis of taxifolin 3 in a high overall yield.

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A Mild and Chemoselective Solvent-Free Method for the Synthesis of N-Aryl and N-Alkylsulfonamides Pp. 235-241

Ahmad R. Massah, Foad Kazemi, Davood Azadi, Shakiba Farzaneh, Hamid Aliyan, Hamid Javaherian Naghash & Ahmad. R. Momeni A variety of N-aryl and N-alkylsulfonamides have been prepared at room temperature in high yield and purity. Selective sulfonylation of amino group in amino phenol was achieved by this method. Also, aromatic amines sulfonylated selectively in the presence of aliphatic amines or phenols.

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Reactions of N-Protected L-Amino Acids with Alkyl Chloromethyl Ethers and Chloromethylmethyl Sulfide Pp. 242-243

Javid H. Zaidi, M. Arfan, Khalid M. Khan*, Shahnaz Perveen & Nida Ambreen Comparative study of esterification of N-protected amino acids with chloromethyl methyl ether, chloromethyl n-butyl ether and chloromethyl methyl sulfide using a convenient general procedure as well as facile and mild deprotection of ester functionality.

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Regio- and Stereoselectivity in the Paternò-Büchi Reaction Between 2,3-Dihydrofuran and Furan with Benzaldehyde Pp. 244-246

Maurizio D’Auria, Lucia Emanuele & Rocco Racioppi The regiochemistry of the attack of the benzaldehyde on the double bond is related to the different stability of the biradical intermediates. The stereoselectivity of the product depends on the superposition between HSOMO and LSOMO in the biradical intermediate.

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Synthetic Approaches to Polar Antimalarial 1,2,4-Trioxanes from C5-Aldehyde and Ipsdienol Pp. 247-249

Axel G. Griesbeck*, Oliver Höinck and Johann Lex New synthetic approaches to polar 1,2,4-trioxanes have been developed from the 4-acetoxy-substituted tiglic aldehyde and the terpene alcohol ipsdienol.

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Regioselective Synthesis of Thieno[3,2-b]Indole by Tandem Cyclization of 1-Acetyl-3-(4'-Aryloxybut-2' -Ynylthio)Indole Pp. 250-252

Krishna C. Majumdar, Safiul Alam & Sanjukta Muhuri Simple and straightforward methodology for the synthesis of thieno[3,2-b]indoles in excellent yield starting from indole using sulfoxide rearrangement.

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