ethyl N-ethoxycarbonyliminocarbamate → HCID 21058145, compound

Participants

Reaction Steps

A solution of (2S,4S)-3-acetyl-5,5-dimethyl-2-phenyl-4-thiazolidinecarboxylic acid (102 g, 0.38 mol) in anhydrous DMF (500 ml) was added to a solution of 3-acetyl-6-chloro-2-(2-hydroxy-5-methoxyphenyl)benzothiazoline (127 g, 0.38 mol) in anhydrous DMF (500 ml) at room temperature. N,N-Dimethylaminopyridine (5.58 g, 45.7 mmol) was added thereto under a nitrogen atmosphere at room temperature with stirring. After ice-cooling, diethyl azodicarboxylate (87 g, 0.50 mol) was added thereto, and then the mixture was stirred under ice-cooling for 15 minutes, at room temperature for one hour and further at an internal temperature of about 40° C. for three days. The reaction mixture was concentrated under reduced pressure, a 10% aqueous citric acid solution (1,000 ml) was added to the residue, and the whole was extracted with ethyl acetate (1,000 ml). The organic layer was washed with water (1,000 ml) and saturated brine (1,000 ml) successively and dehydrated with magnesium sulfate. Ethyl acetate was evaporated under reduced pressure, a mixed solvent (ethanol/diisopropyl ether=200 ml/1,000 ml) was added to the residue, the residue was dissolved by heating, and then the solution was allowed to stand at room temperature overnight. One precipitated diastereomer was filtered out, and the mother liquor was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (mobile phase: hexane/ethyl acetate=1/1) to give 78.0 g (43%) of the target compound.

Provenance & Evidence