Unlocking Cyclic Carbonates as Butadiene Surrogates in Pd-Catalyzed Mizoroki-Heck Reactions

We herein report a modular strategy for the Pd-catalyzed synthesis of diverse phenyl-1,3-dienes from vinyl ethylene carbonate (VEC) and phenylboronic acids. The key feature of this work is that the VEC acts as a diene surrogate upon decarboxylation, which paves the way for the formation of π-allylpalladium intermediates. These intermediates are intercepted by phenylboronic acid, resulting in symmetric diphenylbutadiene and 1-phenylbutadiene, along with unsymmetric products. Interestingly, all of the 1,3-diene derivatives were synthesized in 2-Me-THF, a green solvent. The key intermediates were characterized by mass spectrometry. This developed protocol represents a significant advancement by refraining from the use of 1,3-butadiene, and products formed by 1,4-difunctionalization retain the conjugated dienes, which is feasible with VEC, an elusive commercial 1,3-butadiene surrogate.