A new synthesis of bridged aromatics: 10,15-dihydro-5H-tribenzo[a,d,g]cyclononene and its analogues

Abstract

Cycloalkylation of benzene using compounds (I), e.g. 2,2′-bis(hydroxymethyl)diphenylmethane, in sulphuric acid produces the bridged aromatic compounds (II) with a novel nine-membered ring system, to which a rigid crown conformation and a flexible form have been suggested for the parent hydrocarbon (IIa) and sulphur analogue (IId), and for the ketone (IIb) and the oxygen analogue (IIc), respectively.