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.