Transformations of N-acetyl(aroyl)-1-azafluorenium chlorides to give 9-α-hydroxyethylidene(arylidene)-1-azafluorenes

N-Acetyl (benzoyl)-1-azafluorenium chlorides were converted to 9-acetyl(benzoyl)-1-azafluorenes, which exist in the enol form, when they were treated with triethylamine in benzene in the presence of boron trifluoride etherate. The first step in the rearrangement is the conversion of the starting chlorides to N-acyl-substituted pseudoazulenes with subsequent N-C9 migration of the acyl group. © 1984 Plenum Publishing Corporation.