Current Organic Chemistry - Volume 20, Issue 7, 2016

Abundant availability of biomass is a greener and bio-renewable resource to govern the bio-based economy by synthesizing energy-rich chemicals. Amongst twelve speciality chemicals, 5-hydroxymethylfurfural (5- HMF) is a potential building block component to synthesize a variety of industrially important organic moieties. In recent times, considerable attention and many efforts have been made by various researchers to produce 5-HMF from lingo-cellulosic biomass. However, efficient production of 5-HMF suffers from various difficulties due to the need of specific solvent and catalytic system. For this purpose, the use of ionic liquid (ILs) has received a special attention. This is because of its enormous potential to work as a “designer solvent” and “catalyst”. This review article mainly focusses on the current research involving the use of ILs as a solvent and catalyst for production of 5- HMF. Various functions of ILs and reaction parameters are discussed in detail with the literature to understand the exact role of IL. Furthermore, an outline of challenges and opportunities related to the use of ILs for 5-HMF production is presented.

As a substitute for traditional fossil fuels, Biodiesel has attracted more attention recently for its nature of environmental friendliness. As catalysts, Ionic liquids which possess unique properties have found important applications for many reactions including production of biodiesel by transesterification. The paper gives a review on the feasibility of using ionic liquids as the catalysts in biodiesel synthesis by transesterification, which is summarized as basic ionic liquid catalyst systems, acidic ionic liquid catalyst systems, and solid material supported ionic liquid catalyst systems.

Heterogeneous catalysis using sole metal-organic frameworks (MOFs) remains an immature field because these MOFs have insufficient active sites. The “inorganic effect” allows MOFs to become solid supports to immobilize polyoxometalates and metal nanoparticles, whereas the “organic effect” enables MOFs to function with organic groups such as -NH2 and -SO3H. These functionalized MOFs can be applied in various reactions, such as oxidation, hydrogenation, Knoevenagel condensation, dehydration, and hydrolysis. This review presents the catalytic transformation of organic molecules and biomass derivatives with MOFs.

In the past several decades, significant progress has been made in the exploration of cyclofunctionalization reactions promoted by electrophilic organoselenium reagents. Numerous natural and biologically active products have been prepared by using this synthetic route. Increased research interest in this topic brings several relevant reviews, which cover wide scope of selenium-induced heterocyclizations. The reaction of electrophile selenium- induced cyclization of alkenes bearing suitable oriented hydroxyl group (termed selenoetherification) present useful tool for the preparation of different cyclic ethers units, which are the key structural units of many natural products. The coverage of this review will be limited to the examples of stereoselective and regioselective synthesis of five- and six-membered cyclic ethers by means of selenium-induced cyclization of unsaturated alcohols. The influence of some Lewis acids and bases, as additives, on regioselection of selenoetherification reaction will be also discussed.

The Pechmann condensation is the formation of coumarin derivatives from phenols and a carboxylic acids or esters containing a β-carbonyl group under acidic conditions. The reaction has attracted a great deal of attention because of the biological significance of coumarins derivatives. As a result, the synthesis of coumarin and its derivatives have been an attractive goal for the chemist. The present review is focused on brief aspects of the synthesis of coumarin derivatives from phenols and a carboxylic acids or esters containing a β-carbonyl group under acidic conditions using various catalysts.