tert-butyl N-[(2S)-1-hydroxypentan-2-yl]carbamate

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

Procedure: To a mixture of phthalimide (1.43 g, 9.72 mmol), ((S)-1-hydroxymethyl-butyl)-carbamic acid tert-butyl ester (prepared according to the procedure described in US 2007/0032433 page 232) (1.97 g, 9.69 mmol) and triphenylphosphine (2.55 g, 9.72 mmol) in DCM (25 mL) at 0° C. is added DEAD (1.6 mL, 10.2 mmol) dropwise. The reaction mixture is stirred at RT overnight. The reaction mixture is adsorbed onto silica gel and purification by chromatograghy (SiO2, 0-15% EtOAc in iso-hexane) affords the title compound as white solid. [M+H]+ 233. prepared at 0° C. The reaction mixture is adsorbed onto silica gel and purification by chromatograghy (SiO2, 0-15% EtOAc in iso-hexane)

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

Procedure: To a mixture of phthalimide (1.43 g, 9.72 mmol), ((S)-1-hydroxymethyl-butyl)-carbamic acid tert-butyl ester (prepared according to the procedure described in US 2007/0032433 page 232) (1.97 g, 9.69 mmol) and triphenylphosphine (2.55 g, 9.72 mmol) in DCM (25 mL) at 0° C. is added DEAD (1.6 mL, 10.2 mmol) dropwise. The reaction mixture is stirred at RT overnight. The reaction mixture is adsorbed onto silica gel and purification by chromatograghy (SiO2, 0-15% EtOAc in iso-hexane) affords the title compound as white solid. [M+H]+ 233. prepared at 0° C. The reaction mixture is adsorbed onto silica gel and purification by chromatograghy (SiO2, 0-15% EtOAc in iso-hexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To Boc-norvalinol (7.77 g, 38 mmol), in anhydrous dimethylsulfoxide (153 mL) and toluene (153 mL) was added EDC (73.32 g, 382 mmol). After the solution was cooled to 0° C., dichloroacetic acid (15.8 mL, 191 mmol) was added dropwise. After addition was complete, the reaction was stirred for 15 min. The solution was allowed to warm to room temperature over a period of 2 h. The reaction mixture was concentrated to remove the toluene, then dissolved in ethyl acetate. The solution washed successively with 1 N sodium bisulfate, saturated sodium bicarbonate and brine, dried over sodium sulfate, filtered and concentrated to afford crude Boc-norvalinal which was used directly in the next step. TLC Rf=0.84 (40% ethyl acetate/hexanes). After addition to warm to room temperature over a period of 2 h The reaction mixture was concentrated to remove the toluene dissolved in ethyl acetate The solution washed successively with 1 N sodium bisulfate, saturated sodium bicarbonate and brine dried over sodium sulfate filtered concentrated

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To Boc-norvalinol (7.77 g, 38 mmol), in anhydrous dimethylsulfoxide (153 mL) and toluene (153 mL) was added EDC (73.32 g, 382 mmol). After the solution was cooled to 0° C., dichloroacetic acid (15.8 mL, 191 mmol) was added dropwise. After addition was complete, the reaction was stirred for 15 min. The solution was allowed to warm to room temperature over a period of 2 h. The reaction mixture was concentrated to remove the toluene, then dissolved in ethyl acetate. The solution washed successively with 1 N sodium bisulfate, saturated sodium bicarbonate and brine, dried over sodium sulfate, filtered and concentrated to afford crude Boc-norvalinal which was used directly in the next step. TLC Rf=0.84 (40% ethyl acetate/hexanes). After addition to warm to room temperature over a period of 2 h The reaction mixture was concentrated to remove the toluene dissolved in ethyl acetate The solution washed successively with 1 N sodium bisulfate, saturated sodium bicarbonate and brine dried over sodium sulfate filtered concentrated

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To Boc-norvalinol (7.77 g, 38 mmol), in anhydrous dimethylsulfoxide (153 mL) and toluene (153 mL) was added EDC (73.32 g, 382 mmol). After the solution was cooled to 0° C., dichloroacetic acid (15.8 mL, 191 mmol) was added dropwise. After addition was complete, the reaction was stirred for 15 min. The solution was allowed to warm to room temperature over a period of 2 h. The reaction mixture was concentrated to remove the toluene, then dissolved in ethyl acetate. The solution was washed successively with 1N sodium bisulfate, saturated sodium bicarbonate and brine, dried over sodium sulfate, filtered and concentrated to afford crude Boc-norvalinal which was used directly in the next step. TLC Rf=0.84 (40% ethyl acetate/hexanes). Step 3. Synthesis of Boc-nVal-(CHOH)-Gly-OEt: After addition to warm to room temperature over a period of 2 h The reaction mixture was concentrated to remove the toluene dissolved in ethyl acetate The solution was washed successively with 1N sodium bisulfate, saturated sodium bicarbonate and brine dried over sodium sulfate filtered concentrated

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

Procedure: To a mixture of phthalimide (1.43 g, 9.72 mmol), ((S)-1-hydroxymethyl-butyl)-carbamic acid tert-butyl ester (prepared according to the procedure described in US 2007/0032433 page 232) (1.97 g, 9.69 mmol) and triphenylphosphine (2.55 g, 9.72 mmol) in DCM (25 mL) at 0° C. is added DEAD (1.6 mL, 10.2 mmol) dropwise. The reaction mixture is stirred at RT overnight. The reaction mixture is adsorbed onto SiO2 and purification by chromatography (SiO2, EtOAc/iso-hexane, gradient of 0-15% EtOAc) affords the title compound as white solid. [M+H]+ 233. prepared at 0° C. The reaction mixture is adsorbed onto SiO2 and purification by chromatography (SiO2, EtOAc/iso-hexane, gradient of 0-15% EtOAc)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To Boc-norvalinol (7.77 g, 38 mmol), in anhydrous dimethylsulfoxide (153 mL) and toluene (153 mL) was added EDC (73.32 g, 382 mmol). After the solution was cooled to 0° C., dichloroacetic acid (15.8 mL, 191 mmol) was added dropwise. After addition was complete, the reaction was stirred for 15 min. The solution was allowed to warm to room temperature over a period of 2 h. The reaction mixture was concentrated to remove the toluene, then dissolved in ethyl acetate. The solution was washed successively with 1N sodium bisulfate, saturated sodium bicarbonate and brine, dried over sodium sulfate, filtered and concentrated to afford crude Boc-norvalinal which was used directly in the next step. TLC Rf=0.84 (40% ethyl acetate/hexanes). After addition to warm to room temperature over a period of 2 h The reaction mixture was concentrated to remove the toluene dissolved in ethyl acetate The solution was washed successively with 1N sodium bisulfate, saturated sodium bicarbonate and brine dried over sodium sulfate filtered concentrated

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To Boc-norvalinol (7.77 g, 38 mmol), in anhydrous dimethylsulfoxide (153 mL) and toluene (153 mL) was added EDC (73.32 g, 382 mmol). After the solution was cooled to 0° C., dichloroacetic acid (15.8 mL, 191 mmol) was added dropwise. After addition was complete, the reaction was stirred for 15 min. The solution was allowed to warm to room temperature over a period of 2 h. The reaction mixture was concentrated to remove the toluene, then dissolved in ethyl acetate. The solution was washed successively with 1N sodium bisulfate, saturated sodium bicarbonate and brine, dried over sodium sulfate, filtered and concentrated to afford crude Boc-norvalinal which was used directly in the next step. TLC Rf=0.84 (40% ethyl acetate/hexanes). After addition to warm to room temperature over a period of 2 h The reaction mixture was concentrated to remove the toluene dissolved in ethyl acetate The solution was washed successively with 1N sodium bisulfate, saturated sodium bicarbonate and brine dried over sodium sulfate filtered concentrated

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

Procedure: To a solution of Boc-norvaline (25.0 g, 0.115 mol) in tetrahydrofuran (461 mL), cooled to 0° C., was added borane/tetrahydrofuran complex (461 mL of a 1.0M solution in tetrahydrofuran) dropwise. After 1 h at 0° C., the solution was warmed to room temperature over a period of 1.5 h. TLC indicated that the reaction was complete. Methanol was added to quench the reaction. The solution was concentrated to yield the title compound (22.56 g, 96%) as a foamy syrup. TLC of the products indicated satisfactory purity. Rf=0.34 (40% ethyl acetate/hexanes). to quench the reaction The solution was concentrated

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

Procedure: To a mixture of phthalimide (1.43 g, 9.72 mmol), ((S)-1-hydroxymethyl-butyl)-carbamic acid tert-butyl ester (prepared according to the procedure described in US 2007/0032433 page 232) (1.97 g, 9.69 mmol) and triphenylphosphine (2.55 g, 9.72 mmol) in DCM (25 mL) at 0° C. is added DEAD (1.6 mL, 10.2 mmol) dropwise. The reaction mixture is stirred at RT overnight. The reaction mixture is adsorbed onto silica gel and purification by chromatograghy (SiO2, 0-15% EtOAc in iso-hexane) affords the title compound as white solid. [M+H]+ 233. prepared at 0° C. The reaction mixture is adsorbed onto silica gel and purification by chromatograghy (SiO2, 0-15% EtOAc in iso-hexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To Boc-norvalinol (7.77 g, 38 mmol), in anhydrous dimethylsulfoxide (153 mL) and toluene (153 mL) was added EDC (73.32 g, 382 mmol). After the solution was cooled to 0° C., dichloroacetic acid (15.8 mL, 191 mmol) was added dropwise. After addition was complete, the reaction was stirred for 15 min. The solution was allowed to warm to room temperature over a period of 2 h. The reaction mixture was concentrated to remove the toluene, then dissolved in ethyl acetate. The solution washed successively with 1 N sodium bisulfate, saturated sodium bicarbonate and brine, dried over sodium sulfate, filtered and concentrated to afford crude Boc-norvalinal which was used directly in the next step. TLC Rf=0.84 (40% ethyl acetate/hexanes). After addition to warm to room temperature over a period of 2 h The reaction mixture was concentrated to remove the toluene dissolved in ethyl acetate The solution washed successively with 1 N sodium bisulfate, saturated sodium bicarbonate and brine dried over sodium sulfate filtered concentrated