Mild and Robust Stille Reactions in Water using Parts Per Million Levels of a Triphenylphosphine‐Based Palladacycle

An inexpensive and new triphenylphosphine‐based palladacycle has been developed as a pre‐catalyst, leading to highly effective Stille cross‐coupling reactions in water under mild reaction conditions. Only 500–1000 ppm of Pd suffices for couplings involving a variety of aryl/heteroaryl halides with aryl/hetaryl stannanes. Several drug intermediates can be prepared using this catalyst in aqueous nanoreactors formed by 2 wt % Brij‐30 in water. Highly valued Stille couplings can now be done not only in water under mild reaction conditions, but with only 500–1000 ppm of Pd ligated with triphenylphosphine, derived from a new and readily prepared palladacycle.