Click Chemistry

Nobel laureate Prof. K. Barry Sharpless introduced the term ‘Click Chemistry’
for the first time in 1999, during the 217th American Chemical Society annual
meeting [23a]. Subsequently, the term gained immense popularity within the scien-
tific community. According to Professor Sharpless, for a chemical transformation to
be considered a ‘Click reaction’, it must fulfill the following criteria:if the reaction is modular, easy to carry out, broad substrate scope, mild reaction condi-
tion, furnished products reasonably in high-to-excellent yields with ease of isolation prefer-
ably through avoid of chromatographic separation, generates only harmless by-products
which can be free from the sole product without any difficulty, and also be regioselec-
tive and stereospecific (but not essentially to be enantioselective), moreover use of readily
available starting materials or reagents and also the use of either solvent-free condition or
environmentally benign solvent that can be removed easily [23b].