Multicarbocycle Formation Mediated by Arenoporphyrin 1,4-Diradicals: Synthesis of Picenoporphyrins

Bergman cyclization of 2,3-dialkynyl-meso-tetraphenylporphyrins and carbon–carbon bond formation (mediated by 1,4-diradicals) with the adjacent meso-phenyl rings lead to formation of an unprecedented multicarbocycle fused onto the porphyrin periphery. The highly π-extended parent molecules (1; R=Bu, H, Ph) are described and are named picenoporphyrins after their [5]phenacene structure.