Efficient conversion of 9-Isopropenylphenanthrene to 4,6,6-trimethyl-6H-benz[de]anthracene in FSO₃H; 5,6-dihydro-4H-benzanthracen-4-ium ion and its charge delocalization mode

Abstract

Low temperature protonation of 9-isopropenylphenanthrene in FSO₃H–SO₂ClF (or FSO₃H–CH₂Cl₂) leads to direct observation of 5,6-dihydrobenzanthracenium cation 4H⁺ from which the corresponding benz[de]anthracene is obtained in 92% yield upon quenching.

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