A solution of 628 mg (1.76 mmol) of 1-(t-butoxycarbonyl)-4-(2,2-bis(carbethoxy)ethyl)piperidine (from EXAMPLE 32, Step B) in 8 mL of THF at 0° C. was treated with 2.0 mL of 1.0 M sodium bis(trimethylsilyl) amide solution in THF and stirred cold for 10 min. The resulting mixture was treated with 0.35 mL (2.9 mmol) of benzyl bromide then warmed to rt and stirred for 1 h. The reaction was quenched with 10 mL of sat'd NH4Cl and the quenched mixture was partitioned between 50 mL of ether and 25 mL of H2O. The layers were separated and the organic layer was washed with 25 mL of sat'd NaCl, dried over MgSO4 and concentrated. Flash chromatography on 30 g of silica gel using 4:1 v/v hexanes/ether afforded 760 mg (96%) of the title compound: 1H NMR (500 MHz) δ 1.08-1.16 (m, 2H), 1.23 (t, J=7.0,66H), 1.45 (s, 9H), 1.54-1.58 (m, 2H), 1.60-1.66 (m, 1H), 1.78 (d, J=6.0, 2H), 2.68 (app t, J=11.5, 21), 3.28 (s, 2H), 4.01 (br s, 2H), 4.15 (q, J=7.0, 4H), 7.06-7.25 (5H).
