Gopinathan Anilkumar

Recent advances and perspectives in copper-catalyzed Sonogashira coupling reactions

C–C bond formation using transition metal catalyzed Sonogashira coupling reaction is an indispensable tool in synthetic organic chemistry. Initially Pd complexes were used as catalysts; however advances in catalyst design fuelled the development of Cu catalysts, which are cheaper and more environmentally benign than the Pd complexes. This is the first review reported so far dealing exclusively with Cu-catalyzed Sonogashira coupling reactions. This review illustrates the current strategies and potential of Cu-catalyzed Sonogashira coupling reactions.

Recent advances and applications of Glaser coupling employing greener protocols

Symmetrical 1,3-diynes and their derivatives are useful motifs for the construction of complex molecules, and their excellent photochemical and material properties received considerable attention in the last decades. They are used for the synthesis of a large variety of polymers, biologically active molecules, supramolecular materials and light harvesting systems. Glaser coupling is the most widely used procedure for the synthesis of 1,3-diynes through the oxidative homocoupling of terminal alkynes. Classical homocoupling is catalysed by copper salts in the presence of a base and an oxidant. Numerous modifications were developed recently to improve the efficacy of Glaser coupling reactions. Novel synthetic routes and approaches employing greener protocols are well appreciable. In addition to terminal alkynes, other susceptible substrates are also tested for the synthesis of 1,3-diynes. These recent advances and perspectives of Glaser coupling reactions are documented in this review. This review highlights the diverse and innovative strategies developed for the synthesis and applications of 1,3-diynes expending green chemistry.

A novel and efficient zinc-catalyzed thioetherification of aryl halides

The first zinc-catalysed protocol for the C–S cross-coupling reaction is reported. Zinc catalysis has an undeniable advantage over other catalytic systems as it is non-toxic, and the catalysts are easily available and cheap, with environmentally benign properties. This novel, efficient, palladium- and triphenylphosphine-free protocol yielded a variety of aryl and alkyl sulfides in moderate to excellent yields.

An overview of Zn-catalyzed enantioselective aldol type C–C bond formation

Enantioselective aldol reactions are powerful tools for the creation of carbon–carbon bonds in a stereoselective manner. Several synthetic strategies have been developed for asymmetric aldol reactions; but among these, Zinc-catalyzed protocols for enantioselective aldol reactions attained great significance due to its excellent functional group tolerance. Zinc catalysis has an undeniable significance over other catalytic systems due to its non-toxic, easily available, cheap and environmentally benign properties. This review mainly focuses on the stereoselective aspects of Zn-catalyzed aldol type reactions promoted by enolate chemistry.

Hydrogels, DNA, and RNA polypeptides for the preparation of biomaterials

Abstract Hydrogels are water-insoluble, three-dimensional networks of polymer chains capable of holding large amounts of water. They are the first biomaterials designed for use in human body and are finding widespread biomedical applications. New methods of synthesis of hydrogels have revolutionized the field of biomaterials. The chapter deals with the different aspects of synthesis of hydrogels, its benefits, and limitations together with the different synthetic hydrogels such as the composite hydrogels, biodegradable hydrogels, superabsorbent hydrogels, and stimuli-sensitive hydrogels. Natural and biocompatible hydrogels such as the alginate-, chitosan-, and protein-based hydrogels are also discussed. The applications of hydrogels in tissue engineering, sensing, and artificial muscles are also discussed. A brief introduction to DNA and RNA along with DNA-based hydrogels is also included.