The nitration of benzosuberone (I) with nitric acid in sulfuric acid gives 3-nitrobenzosuberone (II), which is reacted with ethylene glycol in the presence of p-toluenesulfonic acid yielding 3-nitrobenzosuberone ethylene ketal (III). The catalytic reduction of (III) using Pd/C affords 3-aminobenzosuberone ethylene ketal (IV), which is treated with an aqueous acid to give 3-aminobenzosuberone (V). Diazotization followed by hexafluorophosphoric acid treatment of compound (V) affords diazofluorophosphate complex (VI), which on heating gives 3-fluorobenzosuberone (VII). Carbethoxylation of compound (VII) with diethylcarbonate gives the beta-ketoester (VIII), which is reacted with guanidine carbonate yielding compound (IX).