Hydrochloric Acid → 2-amino-6-borono-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)hexanoic acid dihydrochloride

Reaction equation

C([NH:4][C:5]([C@@H:26]1[CH2:30][CH2:29][N:28]([CH2:31][C:32]2[CH:37]=[CH:36][C:35]([F:38])=[CH:34][CH:33]=2)[CH2:27]1)([CH2:13][CH2:14][CH2:15][CH2:16][B:17]1[O:21]C(C)(C)C(C)(C)[O:18]1)[C:6](NC(C)(C)C)=[O:7])(=O)C.[ClH:39].[OH2:40]>>[ClH:39].[ClH:39].[NH2:4][C:5]([C@@H:26]1[CH2:30][CH2:29][N:28]([CH2:31][C:32]2[CH:37]=[CH:36][C:35]([F:38])=[CH:34][CH:33]=2)[CH2:27]1)([CH2:13][CH2:14][CH2:15][CH2:16][B:17]([OH:21])[OH:18])[C:6]([OH:7])=[O:40]

Participants

Reactant 3

HCID 313Hydrochloric Acid

HCID 962Water

HCID 668334802-acetamido-N-tert-butyl-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanamide

Product 1

HCID 668329562-amino-6-borono-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)hexanoic acid dihydrochloride

Procedure

An aqueous solution of 2-acetamido-N-tert-butyl-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanamide (0.280 g, 0.527 mmol) in 6M hydrogen chloride (10 mL, 60 mmol) was heated under reflux overnight. The reaction was cooled to room temperature, diluted with 20 mL of water, and washed with ethyl acetate (20 mL). The aqueous layer was purified by HPLC (3 injections) using a 5-20% acetonitrile in water. The fractions corresponding to the desired product were concentrated and lyophilized to give 2-amino-6-borono-2-((R)-1-(4-fluorobenzyl)pyrrolidin-3-yl)hexanoic acid dihydrochloride as white powder, which became oily upon exposure to air (hydroscopic). (0.003 g, 2%). 1H NMR (400 MHz, CDCl3, Mixture of diastereoisomers) δ 7.41 (dd, J1=8.1 Hz, J2=6.5 Hz, 2H), 7.12 (t, J=8.1 Hz, 2H), 4.35-4.25 (br, m, 2H), 3.77-3.09 (br. m, 3H), 2.99-2.60 (br. m, 1H), 2.39-1.57 (br. m, 4H), 1.34-1.18 (br. m, 2H), 1.15-1.03 (br. m, 1H), 0.70-0.61 (m, 2H),; ESI MS found for C17H26BFN2O4 m/z 335.3 (M+H-water)+; 351.4 (M−H)−; 333.4 (M−H-water)−.