Environmentally friendly [Pd/Cu]-catalysed C3-alkenylation of free NH-indoles

A new eco-efficient and environmentally friendly palladium/copper catalytic procedure for the C3-alkenylation of free NH-indoles is reported. Using homogeneous or heterogeneous heterobimetallic [Pd/Cu]-catalysts under mild reaction conditions (10 mol% Pd-catalyst and 10 mol% Cu-catalyst, 70 °C, air), substituted indoles are fully (58–82% isolated yields) and selectively (75–100% selectivity) converted to the expected 2-substituted-3-vinylindoles.