ethyl N-ethoxycarbonyliminocarbamate → HCID 21058145, compound

Participants

Reaction Steps

A solution of (2S,4S)-3-acetyl-5,5-dimethyl-2-phenyl-4-thiazolidinecarboxylic acid [compound described in Reference Example 4 (b)] (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. 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, and ethyl acetate was evaporated under reduced pressure. A mixed solvent (ethanol/diisopropyl ether=200 ml/1000 ml) was added to the residue, the residue was dissolved by heating, and then the solution was allowed to stand at room temperature overnight. The precipitated crystals were filtered off and dried to give 34.7 g of the target compound. The mother liquor was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (mobile phase:hexane/ethyl acetate=1/1) to give further 43.8 g of the target compound (total 43%).

Provenance & Evidence