Reaction of benzothiazolone (I) with propionyl chloride in the presence of triethylamine in refluxing THF provided the N-propionyl derivative (II), which was subsequently rearranged by heating at 165 C with AlCl3 to give ketone (III). Alkylation of (III) with 1-(2-chloroethyl)piperidine and K2CO3 in hot DMF yielded (IV), which was finally reduced with triethylsilane in trifluoroacetic acid to the propyl derivative.