The effect of bond structure on the transformation of o-aroyloxyacetoarones into o-hydroxydiaroylmethanes. Baker-Venkataraman transformation

Abstract

The experimental results indicate that the Baker-Venkataraman transformation of o- aroyl-oxyacearones into o- hydroxydiaroylmethanes takes place more rapidly across the 2 : 3 - bond (single bond) in naphthalene than across 1 : 2 - bond (double bond). this is attributed to easter - type neutralisation across the double bond, and is in accordance with the view (Doyle et al., Proc, Roy, Dublin Soc., 1948, 24, 291) that the transformation involves a base - catalysed intramolecular Claisen condensation. Preliminary result with o- aroyloxyacetylindanes do not seem to be in accord with the Mills- Nixon view of bond distribution in indane. The tendency of o- hydroxydiarolmethanes, HO CO·CH₂·CO·R to undergo spontaneous cyclisation to the corresponding flavones when R contains an electrophilic (nitro) group is discussed. A number of new 4- pyrones are described. It has not been foud possible to transform o- arylsuphonyloxyacephenones.