N-Boc-trans-4-amino-L-proline methyl ester

Acetic acid (42 pL, 0.73 mmcl) was added to a solution of 1 -(tert-butyl) 2-methyl (2S, 4R)-4-aminopyrrolidine- 1 , 2-dicarboxylate (7.48 g, 30.6 mmcl) and tert-butyl (2-oxoethyl)carbamate (4.64 g, 29.2 mmcl) in MeOH (194 mL) and the reaction stirred at roomtemperature for 3 h. The solution was cooled to 0 00 and sodium triacetoxyborohydride (9.27 g, 43.7 mmol) was added portion-wise. The reaction stirred overnight while slowly warming toroom temperature. The reaction mixture was concentrated under reduced pressure and theresulting residue was diluted with DCM washed sequentially with saturated sodiumbicarbonate, water and saturated sodium chloride. The organic layer was dried over Na2SO4, filtered and concentrated to dryness. The crude material was purified by silica gel chromatography (DCM/EtOAc/MeOH) to afford 1 -tert-butyl 2-methyl (2S, 4R)-4-[2-(tert- butoxycarbonylamino)ethylamino]pyrrolidine- 1 , 2-dicarboxylate (Intermediate 72, 4.77 g, 42%yield) as a colorless oil. 1H NMR (500MHz, DMSO-d6) 51.25- 1.48 (20H, m), 1.84-2.07 (3H, m), 2.88-2.98 (2H, m), 3.02-3.17 (1H, m), 3.17-3.27 (1H, m), 3.40-3.51 (1H, m), 3.64(3H, s), 4.14-4.24 (1 H, m), 6.63-6.74 (1 H, m); m/z: (ESj [M+H] = 388.

Molecular Weight:244.29
XLogP3:0.3
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:4
Exact Mass:244.14230712
Monoisotopic Mass:244.14230712
Topological Polar Surface Area:81.9
Heavy Atom Count:17
Complexity:311
Defined Atom Stereocenter Count:2
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes