Current Organic Synthesis - Volume 9, Issue 1, 2012

Current Organic Synthesis now enters its ninth year since it started publication. It has grown over the years to be highly regarded among the community of synthetic organic chemists and today it has a very respectable Impact Factor of 3.95. This has been possible due to the constant support from the Associate Editors, Guest Editors and Editorial Board Members as well as the eminent authors who have chosen to publish their work in this journal. I am most grateful to all of them. I would also like to thank the very hard working and dedicated staff of Bentham Science Publishers including Ms. Humaira Hashmi, Mrs. Rehana Raza Siddiqui and Mr. Asad Ali who are constantly striving for excellence.

Dr. Devdutt Chaturvedi obtained his Ph. D. degree in Medicinal Chemistry, from the Medicinal Chemistry Division of the Central Drug Research Institute (CSIR), Lucknow, India, in the year 2003. Thereafter, He worked as a Postdoctoral Fellow at the University of Georgia, USA. Later on, he has also worked as a Postdoctoral Fellow at the Institute of Organic Chemistry, University of Goettingen, Germany. He returned to India and worked shortly as a Senior Postdoc at the Department of Chemistry, IIT, Madras and as a Scientist (Fellow) at the Bioorganic Chemistry Division, Indian Institute of Integrative Medicine (CSIR), Jammu. He has worked on several areas of organic synthesis and medicinal chemistry such as design and synthesis of novel class of antidiabetic, antifertility, anti-HIV/HBV, anti-cancer, antimalarial, antimicrobial agents wherein he has worked on the various kinds of structurally diverse synthetic/natural molecules such as steroids, terpenoids, nucleosides, structurally diverse heterocycles, carbamates and related compounds. He has published more than 50 research papers in reputed international journals and filed 11 patents. His work has further recognized from the various kinds of awards such as Most Cited Paper Award (2006-2009) for one of his Tetrahedron letters publication, Young Scientist Award (2008-2009) from the Govt. of Uttar Pradesh, DST-Fast Track Young Scientist Award (2010) from Govt. of India. He is presently working at the Natural Products Chemistry Division of the North-East Institute of Science and Technology (CSIR), Jorhat, Assam, India on design and synthesis of novel class of natural products based antimalarial and anticancer agents and developments of novel synthetic methodologies for bioactive molecules. Dr. Nabin C. Barua obtained his PhD degree in Natural Products Chemistry Division of North-East Institute of Science and Technology (CSIR) in 1981, under the supervision of Dr. R. P. Sharma. Later on, he worked as an AvH-Post-doctoral Fellow with Prof. Dr. Richard R. Schmidt, at the University of Konstanz, Germany, where he worked on the chemistry of functionally substituted vinyl carbanions. He joined NEIST, Jorhat in 1981, where he is currently working as a chief scientist and Head of the Natural Products Chemistry Division. His has worked on various areas of organic chemistry such as isolation and characterization of bioactive natural products from plants, development of novel synthetic methodologies, structural modifications of biologically active natural products for value addition and stereoselective total synthesis of biologically active natural products. He has trained many masters, doctoral and postdoctoral students and published 100 research papers in reputed international journals and also filed 23 patents. He has delivered many invited talks in various national and international symposia.

Synthesis of organic compounds through a series of synthetic steps involves use of a variety of organic chemicals/solvents which are harmful either directly or indirectly. In recent years, water and ionic liquids have emerged as powerful green reaction media for various organic transformations and are frequently employed in organic synthesis affording excellent yields of the desired products. Several researchers in recent time have reviewed the role of water and ionic liquids from time to time. The present hot topic issue will give an overview of the role of these green solvents in the synthesis of diverse compounds under mild reaction conditions. This hot topic issue contains seven review articles authored by scientists from different parts of the world, highlighting the role of ionic liquids/water on the various chemical reactions. I. Fabio Marinelli reviewed a variety of copper mediated organic transformations in water, covering arylation of nucleophiles, alkyne coupling, dipolar cycloadditions, Diels-Alder reactions, oxidations, condensations and enantioselective reactions. II. We have reviewed the recent developments on the role of water in the variety of C-C bond forming reactions such as Sonogashira, Suzuki, Heck, Stille coupling reactions and metathesis reaction and synthesis of some interesting heterocycles using C-C bond forming reactions. III. Franca Bigi and Carla Quarantelli have reviewed the various kinds of Knoevanagel condensations in water, dealing with an exhaustive outcome on this reaction…..

Cu-based catalysts represent a powerful tool for a variety of synthetic transformations, including arylation of nucleophiles, alkyne coupling, dipolar cycloadditions, Diels-Alder reactions, oxidations, condensations and enantioselective reactions. The use of water as reaction medium for these procedures is currently emerging as a very active research field. The present Review focuses on the more synthetically useful “on water” Cu-mediated processes, in which organic co-solvents are absent (or present in negligible amount), and covers the literature until the end of 2009.

In recent years water has emerged as a versatile solvent for the synthesis of a variety of organic compounds employing plethora of organic reactions. Water as a solvent is not only inexpensive and environmentally benign, but also exhibits new reactivity. The types of organic reactions in water are broad including pericyclic reactions, reactions of carbanion equivalents, reactions of carbocation equivalents, reactions of radicals and carbenes, transition metal catalysis, oxidations-reductions, etc. In the present review, we are focusing on some recent and most important carbon-carbon bond forming reactions utilizing water as a reaction media published from the year 2005 onwards.

The Knoevenagel condensation is an important C-C bond forming reaction which has been extensively studied and also applied in industrial processes. Although it involves a dehydration step, the reaction can be successfully carried out in water to produce electron deficient alkenes and heterocyclic compounds such as coumarins. Here we review our works and recent articles concerning the Knoevengel condensation in water. The review is split up in two sections: the first dealing with Knoevenagel condensations in water under heterogeneous catalysis, and the second showing examples of uncatalysed Knoevenagel condensations in water.

Frequently, in spite of the use of a green reagent (the electron), the electrochemical methodologies are unable, owing to the presence of VOCs-supporting electrolytes solutions, to suggest very eco-friendly and competitive procedures of organic synthesis. In this paper, the possible utilization of room temperature ionic liquids, RTILs, as environmental-friendly solvents, instead of volatile and toxic solvents VOCs containing massive quantities of supporting electrolytes, has been reported. In addition, some new procedures of electroorganic synthesis, concerning the double role of RTILs as green solvents and precursors of electrogenerated N-heterocyclic carbenes (as organocatalysts and bases) have been emphasized.

A novel class of chiral ammonium and imidazolium-based ionic liquids containing a chiral moiety and a free hydroxyl function has been designed and synthesized using (-)-ephedrine, isosorbide and isosmannide as naturally chiral sources. Some physical properties of these salts such as melting point, glass-transition temperature, thermal degradation, chemical stability and specific rotation have been characterized. These chiral ionic liquids were found to catalyze the asymmetric Baylis-Hillman reaction, aza Diels-Alder reaction and Michael addition giving good yields and moderate stereoselectivities. Chiral ionic liquids are recycled while their efficiency is preserved.

This review presents the recent applications of RTILs (Room Temperature Ionic Liquids) as reaction media in the main oxacyclic synthesis. Advantages and disadvantages of this green reaction media are described throughout the manuscript. Specifically allusion is made to the rates, mild conditions, co-catalyst, toxicity as well as the possibility of RTIL recycle, compared to the classical volatile organic compounds (VOCs). By showing all the information collected from the literature about this topic, we also expect to motivate the wide scientific community involved in the field of organic synthesis, to use RTILs as environmental friendly solvents and encourage the research on green chemistry.

Due to their unique properties, ionic liquids (ILs) have become increasingly popular over the last few years in the field of green organic synthesis. This review provides an introduction to ionic liquids and aims specifically to describe diverse, recent applications of ILs in three main areas of organic synthesis: single-step chemical reactions in ILs, multistep reactions involving IL-phase synthesis, and multistep reactions in which ILs were used as reaction media for organic syntheses. The significance of greener ILs, including their easy work-up by straightforward extraction, high-yield isolation and purification, remarkable reaction selectivity, and efficient reusability, will also be discussed.

This Review reports recent developments in the synthesis of benzo-fused heterocycles through Pd-catalyzed carbon-carbon and carbon-heteroatom bond forming reactions via direct C-H activation. Nitrogen-, oxygen- and sulfur-containing heterocyclic rings can be rapidly assembled starting from precursors with minimal preactivation. Compared to classical coupling reactions (i.e. Suzuki, Stille, Buchwald-Hartwig), these methods provide a more straightforward and economical route to various heterocyclic scaffolds, which is of practical importance considering their role in biology and pharmaceutical industry.

The polymer nanocomposites are composed of different nanometer units and organic polymer materials. In this review article, we have summarized different novel nanometer units which can be divided into inorganic materials and organic materials. For (inorganic materials)-polymer nanocomposites, the nanometer units include inorganic nanoparticle materials and inorganic nano-layered materials. The synthesis techniques, properties and applications of these different polymer nanocomposites are also summarized. Because of the nano-scale effects, large specific surface area, and highly activated atoms of the polymer nanocomposites, most of the polymer nanocomposites have a lot of special properties such as catalytical properties, electrochemical properties, mechanical properties, magnetical properties, optical properties, biological properties etc. This review article outlines the applications of the polymer nanocomposites in different fields. These polymer nanocomposites can be used as electrodes, catalysts, functional textile fibers, electrolytes, drugs, biomedical materials, fabrications membranes, etc. Meanwhile, the preparation methods of the polymer nanocomposites such as sol-gel synthesis, oxidative polymerization synthesis, thermally synthesis, microwave-induced synthesis, interaction synthesis, one-pot synthesis, templatedirected synthesis, melt mixing synthesis, electrochemical synthesis, catalytic chain transfer polymerization synthesis, self-assembly synthesis, photopolymerization synthesis, reversible addition-fragmentation chain-transfer polymerization synthesis, emulsion polymerization synthesis and inter-matrix synthesis are introduced in this review article detailedly and systematically. This review article will provide the scientific researchers real inspiration to develop new synthesis techniques for different polymer nanocomposites.

tert-Butyl esters are frequently employed in multi-step synthesis, especially with amino acid derivatives, and their importance is well established. On the contrary, tert-butyl ethers received less attention owing to the difficulties in their preparation and cleavage. Recently the tert-butyl ethers found employment also as fuel additives thus their synthesis became important and various protocols were developed. The present article will cover the developments of the synthesis and cleavage of the tert-butyl esters and the tert-butyl ethers in the new millennium.