Bredt's rule. IV—the structure of an alleged bicyclo[3.3.1]nonan-2-ol-9-one

Claims that the condensation product of (?)-menthone with benzylideneacetophenone is a bridged bicyclic ketol are shown to be erroneous. The true structure is shown by ¹³C n.m.r. to be 2-(1′,3′-diphenyl-3′-oxopropyl)-3-methyl-6-isopropylcyclohexanone.