Sodium Chloride → 2,6-Dimethyl-3-carbotert.-butoxy-4-(2-nitrophenyl)-5-methylsulphonyl-1,4-dihydro pyridine

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Reaction Steps

4.5 g of o-nitrobenzaldehyde, 6.3 g of 3-aminocrotonic acid tert.-butyl ester and 4.1 g of methylsulphonylacetone are stirred in 30 ml of hexamethylphosphoric acid triamide for 8 hours under nitrogen at a bath temperature of 110° C. The mixture is cooled and dissolved in 200 ml of ethyl acetate and the solution is treated with a mixture of 200 ml of water, 30 ml of methanol and 30 ml of sodium chloride solution. The aqueous phase is separated off and the organic phase is washed three times with 50 ml of water, twice with 50 ml of 1 N hydrochloric acid, twice with 50 ml of sodium bicarbonate and once with 50 ml of 2 N sodium carbonate solution. The organic phase is separated off and dried. The residue is recrystallised from isopropanol. 2,6-Dimethyl-3-carbotert.-butoxy-4-(2-nitrophenyl)-5-methylsulphonyl-1,4-dihydro pyridine, which is thus obtained, melts at 152°-155° C.

Provenance & Evidence