The condensation of acetophenone (I) with 2-chlorobenzoyl chloride (II) in pyridine gives the corresponding ester (III), which is treated with KOH in hot pyridine yielding the diketone (IV). The cyclization of (IV) with H2SO4 in acetic acid at 100 C affords the benzopyranone (V). The hydrolysis of the acetate group of (V) with NaOH in methanol/water affords the piperidinol (VI), which is finally demethylated with pyridinium hydrochloride at 210-20 C. Alternatively, the ester (III) can be cyclized directly to benzopyranone (V) by means of NaH in hot dioxane.

The condensation of acetophenone (I) with 2-chlorobenzoyl chloride (II) in pyridine gives the corresponding ester (III), which is treated with KOH in hot pyridine yielding the diketone (IV). The cyclization of (IV) with H2SO4 in acetic acid at 100 C affords the benzopyranone (V). The hydrolysis of the acetate group of (V) with NaOH in methanol/water affords the piperidinol (VI), which is finally demethylated with pyridinium hydrochloride at 210-20 C. Alternatively, the ester (III) can be cyclized directly to benzopyranone (V) by means of NaH in hot dioxane.