Isopropanol → HCID 131715517, compound

Participants

Reaction Steps

A solution of 6.8 g of (S)-3-nitrobenzylideneacetoacetic acid 1-phenylethyl ester in a mixture of 20 ml of isopropanol and 10 ml of dimethylformamide was treated under argon with 4.40 g of 4-amino-N-isopropyl-2-oxo-3-pentenesulfonamide and the mixture was thereupon heated to reflux for 8 hours. After concentration under reduced pressure the oily residue was chromatographed on 800 g of silica gel with methylene chloride/ethyl acetate (4:1) as the elution agent, whereby the two expected epimers were eluted as a mixture. The homogeneous fractions yielded an oil which was taken up in 300 ml of ether and left to stand at room temperature overnight. The crystallized-out product was filtered off, washed with a small amount of ether and recrystallized from ethanol. There were obtained 2.3 g of (R)-1,4-dihydro-5-[(isopropylsulfamoyl)acetyl]-2,6-dimethyl-4-(3-nitrophenyl)nicotinic acid (S)-1-phenylethyl ester in the form of yellow crystals, m.p. 151°-153°, specific rotation: [α]54620 =+518° (c=1.0% w/v, ethanol). On the basis of the NMR spectrum this was the (+)-enantiomer of the racemate A described in Example 14.

Provenance & Evidence