Expeditious synthesis of 1,1-diarylethylenes related to isocombretastatin A-4 (isoCA-4) via palladium-catalyzed arylation of N-tosylhydrazones with aryl triflates

A quick and efficient entry to 1,1-diarylethylenes via the reaction of polyoxygenated aryl N-tosylhydrazones with aryl triflates is described. The reaction employs the catalytic system Pd(OAc)2/XPhos, tBuOLi as the base and dioxane as the solvent. A variety of substituents on both the coupling partners' hydrazones and triflates are tolerated. This procedure provides a complementary route to the existing methods for the access to 1,1-diarylethylenes of biological interest.