Synthesis Involving Metals

A wide spectrum of synthetic methods have been used towards the synthesis of isocoumarins and 3,4-dihydroisocoumarins91. A number of newmethods 92-102 are being developed and reported each year. Some of these methods provide the isocoumarins directly whereas others lead to the 3,4- dihydroisocoumarins. Some of the most important, high yield methods applicable to the synthesis of a large number of these compounds are mentioned below. Literature reveals that isocoumarins and 3,4-dihydroisocoumarins have been extensively prepared by such methods, involving metallation at specificposition like lithiation, silylation and thallation etc.