Condensation of 4-azafluorenone and 9-phenacylidene-4-azafluorene with acetophenone. Synthesis of 3′-oxo-spiro-[4-azafluorene-9,1′-indane]

Condensation of 4-azafluorenone and 9-phenacylidene-4-azafluorene with acetophenone leads to the formation of 9,9-diphenacyl-4-azafluorene and 9-(1′,2′-dibenzoylethylidene)-4-azafluorene. The structures of these products were confirmed based on their spectral and chemical data. The conversion of 9,9-diphenacyl-4-azafluorene to 3′-oxo-spiro-[4-azafluorene-9,1′-indane] represents a novel method for the preparation of this heterocycle. © 1989 Plenum Publishing Corporation.