Carbamic acid, [(1R)-1-methyl-2-oxoethyl]-, 1,1-dimethylethyl ester (9CI)

79069-13-9

82353-56-8

The general procedure for the synthesis of (R)-2-(tert-butoxycarbonylamino)propanal from N-Boc-L-alaninol was as follows: to a solution of oxalyl chloride (3.1 g, 24.5 mmol) in anhydrous dichloromethane (DCM, 200 mL) was slowly added dimethylsulfoxide (DMSO, 2.9 mL, 40.8 mmol) at -60 °C. The reaction mixture was stirred at this temperature for 30 minutes. Subsequently, a solution of tert-butyl (R)-(1-hydroxypropan-2-yl)carbamate (3.5 g, 20 mmol) in dichloromethane (DCM, 20 mL) was slowly added at -60 °C. The resulting solution continued to be stirred at -60°C for 30 minutes. Next, triethylamine (11.1 mL, 80 mmol) was added at -60 °C and the reaction mixture was gradually warmed to room temperature and stirring was continued for 2 hours. Upon completion of the reaction, water (100 mL) was added for quenching and the mixture was extracted with dichloromethane (3 x 50 mL). The organic layers were combined, washed with brine, dried over anhydrous sodium sulfate (Na2SO4), and the filtrate was filtered and concentrated to afford the target product (R)-2-(tert-butoxycarbonylamino)propanal (aldehyde 322) as a light yellow oil (3.2 g, 94% yield), which could be used in the subsequent steps without further purification.