A simple, fast and green synthetic protocol is described for one-pot aldolization of isatins and ketones under ultrasound irradiation and conventional thermal method. The 3 mol % of ruthenium catalyst is sufficient to catalyze the aldol reaction of ketones and isatins provided aldol adducts in moderate to good yield and complete diastereoselectivity. Compared with classical methods, ultrasound irradiation procedure provided shorter reaction times and higher yields. The methodology highlights the importance of low catalyst loading in achieving high chemoselectivity under silent and sonochemistry. As this approach involves time conservation and minimal waste generation, it is embraced as a green chemistry method.

Isatin, Ruthenium catalyst, Aldol reaction, Sonochemistry

An investigation into new catalytic approaches for aldol reaction of isatin using RuII serves as valuable addition to the existing methods and expands the horizons of Ru catalyst. Compared to conventional heating which provides thermal energy in the system, sonification reduces reaction times, and minimizes side product formation in good yield and complete diastereoselectivity.

Elahe Keshavarz (2016). An Efficient and Green Synthesis of isatin Derivatives under Ultrasound Irradiation , Biological Forum – An International Journal 8(1): 283-286.