Ultrasound-facilitated direct meta-C-H functionalization of arene: A time economical strategy under ambient temperature with improved yield and selectivity.

The horizon of ultrasound-assistance has been expanded to palladium-catalyzed distal C-H functionalization of arenes. Compared to thermal condition, operationally simple ultrasound mediated distal C-H functionalization occurred with shorter reaction time, enhanced reactivity of reactants in superior yield with improved selectivity both in terms of meta :others and mono:di. Wide variety of meta- functionalizations such as olefination, alkylation, acetoxylation, allylation and cyanation were successfully carried out under ambient temperature.