Kinetically Controllable Pd-Catalyzed Decarboxylation Enabled [5 + 2] and [3 + 2] Cycloaddition toward Carbocycles Featuring Quaternary Carbons.

A decarboxylative protocol has been developed toward a range of carbocycles. The key success is based on the use of a batch of newly designed cyclic carbonates as substrates that can provide carbon-carbon zwitterion intermediate under palladium catalysis. The kinetics of the reactions are controllable toward either strained seven- or thermodynamically more favored five-membered carbocycles. The release of this chemistry will shed light on the synthesis of complex and valuable cyclic structures.