Carbamic acid, [(1R)-3-hydroxy-1-methylpropyl]-, 1,1-dimethylethyl ester (9CI)

To a solution of (R)-3-((tert-butoxycarbonyl)amino)butanoate (3.0 g, 14.76 mmol) in tetrahydrofuran (THF) (50 mL) was added aluminum(III) lithium hydride (0.728 g, 19.19 mmol), stirred at -78 °C for 1 h under nitrogen. The reaction mixture was warmed to 0°C, quenched by addition of H100 g of N-Boc-(R)-3-aminobutyric acid and 300 mL of tetrahydrofuran were placed in a reaction flask, 20.6 g of sodium borohydride was added in portions, the temperature was lowered to -20 °C, and 100 g of boron trifluoride etherate was slowly added dropwise. HPLC to determine whether the raw material reaction is complete. After completion of the reaction, the reaction was quenched by the addition of methanol, and the solvent was evaporated. Filter to remove solids, The filtrate was washed with 100 ml of saturated sodium bicarbonate.The organic phase was concentrated to give N-Boc-(R)-3-aminobutanol as a white solid, 88 g, yield 95percent, mp. 99.0percent (HPLC method).115 g of the compound of formula I was dissolved in 460 mL of tetrahydrofuran, cooled to 0~10 ° C. in an ice bath, 23.7 g of sodium borohydride was added in portions, the temperature was controlled at 0~10 ° C., and 165.4 g of elemental iodine Of 230 mL of tetrahydrofuran solution, the dropwise addition, and gradually warmed to 25 ~ 30 ° C, Liquid phase tracking is complete until the conversion of the raw material, 60 mL of water is added dropwise to quench the reaction, concentrated under reduced pressure to no distillate, 500 mL of methanol is added, the temperature is raised to 55-60 ° C., the solution is incubated for 0.5 h, mL water, drops After completion of the incubation, the mixture was stirred for 1 hour, then slowly cooled to 15-20 ° C, filtered and dried to obtain 97.4 g of the compound of formula II in a yield of 91percent.Example 36 To a solution of (R)-3-((tert-butoxycarbonyl)amino)butanoate (3.0 g, 14.76 mmol) in tetrahydrofuran (THF) (50 mL) was added aluminum(III) lithium hydride (0.728 g, 19.19 mmol), stirred at -78 °C for 1 h under nitrogen. The reaction mixture was warmed to 0°C, quenched by addition of H100 g of N-Boc-(R)-3-aminobutyric acid and 300 mL of tetrahydrofuran were placed in a reaction flask, 20.6 g of sodium borohydride was added in portions, the temperature was lowered to -20 °C, and 100 g of boron trifluoride etherate was slowly added dropwise. HPLC to determine whether the raw material reaction is complete. After completion of the reaction, the reaction was quenched by the addition of methanol, and the solvent was evaporated. Filter to remove solids, The filtrate was washed with 100 ml of saturated sodium bicarbonate.The organic phase was concentrated to give N-Boc-(R)-3-aminobutanol as a white solid, 88 g, yield 95percent, mp. 99.0percent (HPLC method).115 g of the compound of formula I was dissolved in 460 mL of tetrahydrofuran, cooled to 0~10 ° C. in an ice bath, 23.7 g of sodium borohydride was added in portions, the temperature was controlled at 0~10 ° C., and 165.4 g of elemental iodine Of 230 mL of tetrahydrofuran solution, the dropwise addition, and gradually warmed to 25 ~ 30 ° C, Liquid phase tracking is complete until the conversion of the raw material, 60 mL of water is added dropwise to quench the reaction, concentrated under reduced pressure to no distillate, 500 mL of methanol is added, the temperature is raised to 55-60 ° C., the solution is incubated for 0.5 h, mL water, drops After completion of the incubation, the mixture was stirred for 1 hour, then slowly cooled to 15-20 ° C, filtered and dried to obtain 97.4 g of the compound of formula II in a yield of 91percent.Example 36