Polyvinylsulfonic acid as a novel Brønsted acid catalyst for Michael addition of indoles to α,β-unsaturated ketones

Polyvinylsulfonic acid as a novel Brønsted acid catalyst has been reported for the Michael addition reaction of indoles to α,β-unsaturated ketones. This catalyst works as a homogeneous Brønsted acid catalyst giving excellent yields of β-indolylketones. The catalytic performance of polyvinylsulfonic acid was then compared with various acidic catalysts under optimized reaction condition and it was found to give better yield of required β-indolylketones. The catalyst is well characterized using IR, XRD and DSC techniques.