The contribution in the journal of Current Organic Synthesis by various authors is as below:
Synthesis and Transformation of Halochromones
Author(s): Sara M. Tome, Artur M.S. Silva and Clementina M.M. Santos
Affiliation: Department of Chemistry & QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
Herein, an overview of the most important developments on the synthesis and reactivity of halogen-containing chromones, namely simple chromones, flavones, styrylchromones, thiochromones and furochromones are reviewed (since 2003).
Sugar Furanoses as Useful Handles for Molecular Diversity
Author(s): Ana M. Gomez, Clara Uriel, Fernando Lobo and Jose Cristobal Lopez
Affiliation: Instituto de Quimica Organica General (IQOG-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
Carbohydrates have been recognized as privileged structures for the regio- and stereo-controlled appendage of pharmacophores to generate new derivatives with potential application in drug discovery processes. Even though most of the carbohydrate templates have been generated from pyranoses, other sugar derivatives have also been employed in the assembly of such structures. In this review, attention has been directed to the use of sugar-furanose platforms, and an account of the recent developments in the generation of furanose-based templates aiming at the generation of molecular diversity, including those from our research group, is presented.
Catalytic Asymmetric Darzens Reactions
Author(s): Peter Bako, Zsolt Rapi and Gyorgy Keglevich
Affiliation: Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, PO Box 91, 1521 Budapest, Hungary.
Optically active α,β-epoxy derivatives can be converted into many types of useful chiral compounds, such as chiral building blocks and synthetic intermediates for biologically active compounds. The most up-to-date and most economical method for the preparation of enantiomeric pure epoxides is the catalytic asymmetric Darzens condensation. The homogeneous phase and heterogeneus phase (phase-transfer [PT]) catalytic methods for the synthesis of chiral α,β-epoxycarbonyl, epoxysulfonyl and epoxy-amide compounds are reviewed. The effect of chiral catalysts on the yields and enantioselectivities of the epoxides was studied in homogeneous phase and under PT conditions. The use of the most important chiral PT catalysts (ephedrinium salts, cinchona-derived salts and chiral crown ethers) in Darzens condensation is also summarized. In some cases, the relationship between the structure of catalyst and its activity is also studied.
Fluorescent Probes for Selective Probing Thiol-containing Amino Acids
Author(s): Jin-Gang Yu, Xiu-Hui Zhao, Lin-Yan Yu, Hua Yang, Xiao-Qing Chen and Jian-Hui Jiang
Affiliation: College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, China and Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education (Central South University), Changsha, Hunan 410083, China.
Thiol-containing biomolecules, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH), play crucial roles in maintaining biological systems. For example, elevated levels of Hcy have been implicated as an independent risk factor for tumor invasion and metastasis. Being associated with a wide variety of cancer progressions, there is a significant interest in looking for the fluorescent detection of such thiol species (Cys, Hcy, and GSH) in cancer cells. Various thiol-specific probes have been developed on the basis of different strategies. This review focuses on recent contributions for the fluorescent or colorimetric sensors for thiol-containing amino acids, with special emphasis on the design and application of novel fluorophores for detecting thiol-containing amino acids with higher sensitivity.
Recent Advances in the Synthesis of Heterocycles from Oximes
Author(s): Edgars Abele and Ramona Abele
Affiliation: Latvian Institute of Organic Synthesis, Riga, LV1006, Latvia.
This review demonstrates that oximes and their derivatives are valuable starting materials for the preparation of many classes of heterocyclic compounds. The main group of reactions includes the cyclization of unsaturated oxime derivatives. Using these starting materials pyrroles, isoxazoles, pyridines and isoquinolines were prepared. Some heterocyclic systems (for example, seven-membered rings) were obtained using the classical Beckmann rearrangement and novel reagents and conditions.
P-C Bond Formation by Coupling Reactions Utilizing >P(O)H Species as the Reagents
Author(s): Erzsebet Jablonkai and Gyorgy Keglevich
Affiliation: Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1521 Budapest, Hungary.
In this review, the methods forming P-C bonds by coupling reactions, utilizing different >P(O)H species, are surveyed systematically. The components of the reactions are organic halides, >P(O)H species comprising dialkyl phosphites, H-phosphinates or secondary phosphine oxides and the catalyst, that is in most cases the complex of palladium or its salts. The Hirao reaction discovered in 1980 is in the focus that is the coupling of aryl halides or other aryl derivatives with mainly dialkyl phosphites in the presence of a variety of catalyst complexes. Beside P-C= and P-C bonds, P-CΞ bonds can also be established. The topic has also green chemical aspect, as it is a serious challenge for organic chemists to elaborate simple and cheap catalyst systems.
Electrogenerated Base Induced Dehydrodimerization and Dehydrotrimerization of Pyrazolones
Author(s): Wei-Cui Li, Zheng-Zheng Zhang, Cheng-Chu Zeng, Li-Ming Hu and Hong-Yu Tian
Affiliation: College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China.
Electrogenerated base induced dehydrocoupling of pyrazol-5-ones was investigated. The results showed that dehydrodimers and dehydrotrimers were generated simultaneously under electrolytic conditions, and their ratio was mainly dependent on the reaction temperature and the nature of the supporting electrolyte. It was observed that the formation of dimer 2 is preferred at lower temperatures and that trimer 3 is preferentially formed at higher temperatures. In addition, higher yields of 3 could be obtained when NaI was used as the supporting electrolyte. The dehydrocoupling reaction of pyrazol-5-ones to form dimer 2 and trimers 3 and 4 was proposed to be through an EGB-induced cascade mechanism.
Synthesis of a Novel Class of gem-Phosphonate-Phosphates by Reductive Cleavage of the Isoxazolidine Ring
Author(s): Olga Bortolini, Iqbal Mulani, Antonio De Nino, Loredana Maiuolo, Alessandro Melicchio, Beatrice Russo and Donatella Granchi
Affiliation: Dipartimento di Chimica e Tecnologie Chimiche, Via P. Bucci, cubo 12C, Universita della Calabria, Rende (Italy).
A new series of gem-phosphonate-phosphates bearing N-alkyl groups and aromatic substituents has been prepared by reductive cleavage of the isoxazolidine ring with metal carbonyls, using the gem-phosphonate-phosphate rearrangement.
Hydration of 5-Oxo-1-Alkynes by a One-Pot Oxy-Iodination/Reduction Sequence: Synthesis of Methyl Ketones with Anchimeric Assistance
Author(s): Julia Trossarello, Adegboyega Egunjobi, Whitney J. Morgan, Rayaj Ahamed and Karelle S. Aiken
Affiliation: Chemistry Department, PO Box 8064, Georgia Southern University, Statesboro, GA 30460, USA.
Methyl ketone derivatives can be accessed from 5-oxo-1-alkynes in an iodine-initiated hydration of the terminal alkynes. Use of molecular iodine in this manner is novel, inexpensive and a greener alternative to the traditional use of transition metal catalysts. Herein, we report the results of a methodology study which sheds light on the underlying mechanism of this new, metal-free reaction. Our findings indicate that the hydration of the alkyne proceeds via an important anchimeric assistance in which the neighboring keto group participates with a 5-exo-dig cyclization.