tert-butyl N-[(2R)-1-amino-3-methyl-1-oxobutan-2-yl]carbamate

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

Procedure: To a stirred solution of Boc-D-Valine amide (10 g, 46 mMol) in CH2Cl2 (200 mL) was added Triethyloxonium hexafluorophosphate (13.0 g, 48 mMol). (The reaction started out as a suspension which gradually cleared.) The reaction was stirred for 48 h at RT, poured into a separatory funnel, washed with 1 N Na2CO3, dried (Na2SO4), filtered and concentrated under vacuum. To the remaining oil was added Benzylamine (5.0 mL, 23 mMol) and EtOH (20 mL). The reaction was stirred at 60° C. for 24 h. After cooling to RT the reaction was evaporated under vacuum. The title compound (14.16 g, >95% pure by LCMS) was obtained without purification as a pale yellow oil which eventually solidified to a waxy solid: MS (ES) m/e 306.4 (M+H)+. poured into a separatory funnel washed with 1 N Na2CO3 dried (Na2SO4) filtered concentrated under vacuum The reaction was stirred at 60° C. for 24 h After cooling to RT the reaction was evaporated under vacuum

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

Procedure: To a stirred solution of Boc-D-Valine (25 g, 115 mMol) in THF (300 mL) at 0° C. was added N-Methylmorpholine (15 mL, 136 mMol) followed by the dropwise addition of isoButyl chloroformate (18 mL, 139 mMol) over 5 minutes. The reaction was stirred at 0° C. for 30 minutes after which a solution of 30 wt. % NH4OH (50 mL, 385 mMol) was quickly poured into the reaction. (Vigorous gas evolution was seen which subsided after a few minutes.) The reaction was allowed to warm to RT and stirred for 4 h. The reaction was concentrated under vacuum on the rotoevaporator to a volume which precipitated most of the product. The thick white slurry was diluted with an equal volume of water, filtered, rinsed with water, pressed dry then dried under vacuum to give the title compound (22.56 g, 91%) as a white solid: 1H NMR (400 MHz, CDCl3) δ 6.17 (br s, 1H), 5.75 (br s, 1H), 5.12 (d, 1H), 4.00 (app. t, 1H), 2.13 (m, 1H), 1.44 (s, 9H), 0.99 (d, 3H), 0.94 (d, 3H). was quickly poured into the reaction (Vigorous gas evolution was seen which subsided after a few minutes.) The reaction was concentrated under vacuum on the rotoevaporator to a volume which precipitated most of the product The thick white slurry was diluted with an equal volume of water filtered rinsed with water pressed dry then dried under vacuum

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

Procedure: To a stirred solution of Boc-D-Valine amide (10 g, 46 mMol) in CH2Cl2 (200 mL) was added Triethyloxoniuim hexafluorophosphate (13.0 g, 48 mMol). (The reaction started out as a suspension which gradually cleared.) The reaction was stirred for 48 h at RT, poured into a separatory funnel, washed with 1 N Na2CO3, dried (Na2SO4), filtered and concentrated under vacuum. To the remaining oil was added Benzylamine (5.0 mL, 23 mMol) and EtOH (20 mL). The reaction was stirred at 60° C. for 24 h. After cooling to RT the reaction was evaporated under vacuum. The title compound (14.16 g, >95% pure by LCMS) was obtained without purification as a pale yellow oil which eventually solidified to a waxy solid: MS (ES) m/e 306.4 (M+H)+. poured into a separatory funnel washed with 1 N Na2CO3 dried (Na2SO4) filtered concentrated under vacuum The reaction was stirred at 60° C. for 24 h After cooling to RT the reaction was evaporated under vacuum

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

Procedure: To a stirred solution of Boc-D-Valine (25 g, 115 mMol) in THF (300 mL) at 0° C. was added N-Methylmorpholine (15 mL, 136 mMol) followed by the dropwise addition of isoButyl chloroformate (18 mL, 139 mMol) over 5 minutes. The reaction was stirred at 0° C. for 30 minutes after which a solution of 30 wt. % NH4OH (50 mL, 385 mMol) was quickly poured into the reaction. (Vigorous gas evolution was seen which subsided after a few minutes.) The reaction was allowed to warm to RT and stirred for 4 h. The reaction was concentrated under vacuum on the rotoevaporator to a volume which precipitated most of the product. The thick white slurry was diluted with an equal volume of water, filtered, rinsed with water, pressed dry then dried under vacuum to give the title compound (22.56 g, 91%) as a white solid: 1H NMR (400 MHz, CDCl3) δ 6.17 (br s, 1H), 5.75 (br s, 1H), 5.12 (d, 1H), 4.00 (app. t, 1H), 2.13 (m, 1H), 1.44 (s, 9H), 0.99 (d, 3H), 0.94 (d, 3H). was quickly poured into the reaction (Vigorous gas evolution was seen which subsided after a few minutes.) The reaction was concentrated under vacuum on the rotoevaporator to a volume which precipitated most of the product The thick white slurry was diluted with an equal volume of water filtered rinsed with water pressed dry then dried under vacuum