Glycosylation in the green chemistry era

According to the IUPAC definition, Green Chemistry or sustainable chemistry is the “design of chemical product and processes that reduce or eliminate the use or generation of substances hazardous to humans, animals, plants and the environment.” John. C. Warner and Paul Anastas formulated ‘twelve principles’ in 1998 to guide the practice of green chemistry. Traditional carbohydrate synthesis generally employs usage of multiple protection and deprotection steps, harmful chemicals, solvents and many harsh conditions which unpleasantly impact health and environment. So new greener methods for the syntheses of glycoconjugates are in dire need and therefore gaining prominence recently. Though the majority of carbohydrate-based compounds are synthesized via chemical methods, a greener alternative which is an enzymatic method for synthesis has also been investigated over past two decades. Polar green solvents, such as water, supercritical fluid, ionic liquid (IL), are generally used in greener methods for carbohydrate synthesis. This chapter aims to bring challenges in developing greener methods for the glycosylation.