Methodology is described by which several classes of masked synthons, the synthetic equivalents of acyl anions and enolates, can be rendered reactive as ligands in the corresponding diorganocuprate complexes. Vinyl ethers and vinylsilanes were studied, and a comparison of their reactivities, stabilities and unmasking characteristics is given. The two classes of reagents prove nicely complementary in terms of their spectrum of reactivity, selectivity, and ease in unmasking. © 1979, American Chemical Society. All rights reserved.