Nalpha-Boc-Nbeta-Cbz-amino-L-alanine methyl ester

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of methyl 3-{[(benzyloxy)carbonyl]amino}-N-(tert-butoxycarbonyl)alaninate (80 g, 230 mmol) in THF (800 mL) was added lithium borohydride (20 g, 920 mmol) at 0° C. The reaction mixture was allowed to warm to room temperature. After 1 hour, the reaction mixture was diluted with water and filtered. The filtrate was concentrated under reduced pressure to give benzyl tert-butyl (3-hydroxypropane-1,2-diyl)biscarbamate. MS ESI calc'd. for C16H25N2O5 [M+H]+ 325. found 325. 1H NMR (400 MHz, CDCl3) δ 7.38-7.35 (m, 5H), 5.11 (s, 2H), 4.70 (s, 1H), 4.13-4.11 (m, 1H), 3.66-3.28 (m, 4H), 2.04 (s, 2H), 1.43 (s, 9H). filtered The filtrate was concentrated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 3-{[(benzyloxy)carbonyl]amino}-N-(tert-butoxycarbonyl)alanine (100 g, 0.29 mol), potassium carbonate (82 g, 0.59 mol) and methyl iodide (42 g, 0.29 mol) in DMSO (1200 mL) was stirred at room temperature. After 12 hours, the reaction mixture was extracted with ethyl acetate, and the organics were separated and concentrated under reduced pressure. The residue was purified by chromatography on silica gel to give methyl 3-{[(benzyloxy)carbonyl]amino}-N-(tert-butoxycarbonyl)alaninate. MS ESI calc'd. for C17H25N2O6 [M+H]+ 353. found 353. 1H NMR (400 MHz, CDCl3) δ 7.36-7.33 (m, 5H), 5.09 (s, 2H), 4.34-4.30 (m, 1H), 3.74 (s, 2H), 3.59 (t, J=6.0 Hz, 2H), 2.62 (s, 3H), 1.44 (s, 9H). the reaction mixture was extracted with ethyl acetate the organics were separated concentrated under reduced pressure The residue was purified by chromatography on silica gel