3-Amino-1-benzylpyrrolidine (I. Sumio and T. Matsuo, Japanese Kokai JP 5328161, published Mar. 16, 1978) is coupled to N-t-butoxycarbonyl norvaline (Boc-nVal) using conventional N-hydroxysuccinimide coupling procedures. The 1-benzyl group is removed by hydrogenolysis in methanol using palladium on carbon catalyst. The 3-(N-Boc-norvalyl)aminopyrrolidine is then reacted with ethyl 8-chloro-4H-quinolizin-4-one-3-carboxylate, the product of Step 3 of Example 58, as described in Step 4 of Example 58, replacing 3-(N-t-butoxycarbonylamino)pyrrolidine with 3-(N-Boc-norvalyl)aminopyrrolidine, to give 8-(3-(N-norvalyl)amino-pyrrolidinyl)-4H-quinolizin-4-one-3-carboxylic acid with the nitrogen of the amino acid protected with a Boc group. The Boc protecting group is removed by standard hydrolysis using trifluoroacetic acid and dilute aqueous hydrochloric acid.
