Palladium-Catalyzed Sequential Vinyl C-H Activation/Dual Decarboxylation: Regioselective Synthesis of Phenanthrenes and Cyclohepta[1,2,3-de]naphthalenes

The application of a C(vinyl), C(aryl)-palladacycle from vinyl-containing substrates is challenging due to the interference of a reactive double bond in palladium catalysis. This Letter describes a [4 + 2] or [4 + 3] cyclization based on a C(vinyl), C(aryl)-palladacycle by employing alpha-oxocarboxylic acids as the insertion units under a palladium/air system. The reaction proceeded through the key vinyl C-H activation and dual decarboxylation sequence, forming phenanthrenes and cyclohepta[1,2,3-de]naphthalenes regioselectively in good yields. The synthetic versatility of this protocol is highlighted by the gram-scale synthesis and synthesizing functional material molecule.

Automated summary

This approach involves a [4 + 2] or [4 + 3] cyclization based on a C(vinyl), C(aryl)-palladacycle, using alpha-oxocarboxylic acids as insertion units under a palladium/air system, resulting in the selective formation of phenanthrenes and cyclohepta[1,2,3-de]naphthalenes in good yields. The synthetic versatility of this protocol is demonstrated through gram-scale synthesis and the synthesis of functional material molecules.