The conjugate addition of nucleophilic species to the β-carbon of R, β-unsaturated systems is a fundamental concept in synthetic organic chemistry. 1 A significant improvement in synthetic design would occur if we could alter the reactivity of Michael acceptors so that 1, 4 addition could be circumvented in favor of other useful transformations. Our discovery of phosphine's ability to induce addition of carbon and oxygen pronucleophiles to the 4- ...