反应详情

To a solution of 7.0 g (25.3 mmole) of ethyl valerimidate hydrochloride [prepared by method of A. J. Hill and I. Rabinowitz, J. Am. Chem. Soc., 48, 734 (1926)] in 35 ml of dry ethanol stirred under N2 at -78° C. was added dropwise a solution of 24 g (23 mmole) of ethyl carbazate in 35 ml of dry ethanol. Precipitation occurred during the addition, which took 20 minutes and was accompanied by a rise in the internal temperature to -50° C. The mixture was allowed to stand at 5° C. for 60 hours and then filtered. The filtrate was concentrated, and the residue was flash chromatographed on a silica gel column (elution with 98.5:1.5 CH2Cl2 --MeOH), yielding a clear oil, homogeneous by TLC in 97:3 CH2Cl2 --MeOH; mass spectrum (FAB) m/e 217 (M+1)+. NMR suggested a mixture of syn and anti isomers.

1. customPrecipitation
2. additionoccurred during the addition, which
3. customwas accompanied by a rise in the internal temperature to -50° C
4. waitto stand at 5° C. for 60 hours
5. filtrationfiltered
6. concentrationThe filtrate was concentrated
7. customchromatographed on a silica gel column (elution with 98.5:1.5 CH2Cl2 --MeOH)
8. customyielding a clear oil
9. additiona mixture of syn and anti isomers