Competition in intramolecular arylation of triphenylmethanols

Abstract

Six new unsymmetrically substituted derivatives of 2-aminotriphenylmethanol (1) have been synthesised. The direction of ring closure following diazotisation and loss of nitrogen is determined by the nature of the intermediates formed. Where aryl radical intermediates are formed, the selectivity parallels that found in intermolecular competition by phenyl radicals, whereas copper-catalysed decomposition of the diazonium ion leads to intermediates which seem, from their selectivity, to possess considerable cationic nature. The slower thermal decomposition of the diazonium ions unexpectedly shows very little selectivity, suggesting that electrostatic interactions predominate in determining a very short lifetime of the crucial intermediate.