Carbon Dioxide → HCID 86746571, compound

Participants

Reaction Steps

Carbon dioxide was added subsurface to a dichloromethane (40 mL) solution containing leucine ethyl ester hydrochloride salt (0.025 mol, 4.89 g), N-cyclohexyl-N',N',N",N"-tetraethylguanidine (0.025 mol, 6.3 g) and triethylamine (0.10 mol, 10.0 g) at -10° C. (ice and salt bath) for 40 min at a pressure of 0 psig. The reaction mixture was transferred via cannula all at once under carbon dioxide to the precooled solution of phosphorus oxychloride (0.025 mol, 3.9 g) in 40 mL dichloromethane. After stirring for 20 min at -10° C. diethylether (50 mL) was added to the reaction mixture. A white ppt formed and was filtered off. The filtrate was concentrated in vacuo and the residue was extracted with 3×25 mL diethylether. The ether layers were concentrated and the residue was distilled under vacuum collecting product, leucine ethyl ester isocyanate, at 53°-58° C. (3.74 g, 81%) of 98.4 % purity as judged by GC. IR (neat) 2261, 1742 cm-1. 1H NMR (CDCl3) δ 4.23 (q, 2H, J=14.2), 3.98 (dd, 1H, Jgem =8.8, Jvic =5.5), 1.84-1.77 (m, 1H), 1.65-1.59 (m, 2H), 1.29 (t, 3H, J=7.2), 0.92 (t, 6H, J=6.7) ppm.

Provenance & Evidence