Palladium(II)-Catalyzed Conjugate Addition of Arylsiloxanes in Water

Palladium-phosphinous acids catalyze the conjugate addition of arylsiloxanes to a wide range of alpha,beta-unsaturated substrates in water. A microwave-assisted procedure is described that uses 5 mol % of POPd1 to afford beta-substituted ketones, aldehydes, esters, nitriles, and nitroalkanes in 83% to 96% yield within 4 h. This method eliminates the need for stoichiometric additives and an excess of arylsiloxane, and does not require an inert atmosphere.