Reaction Steps
350 grams of the isomeric intermediate from Example 4 was added to a solution of 731 mL of dimethylsulfoxide and 2923 mL of dimethylformamide. The mixture was cooled to 8-12° C. and compressed air was passed through the mixture. 117.5 mL of 50% aqueous sodium hydroxide was added in one portion and the resulting mixture was stirred for 4.5 h. The reaction mixture was added by cannula over 30-60 min to 8.25 L of a stirred 1N hydrochloric acid solution at 10-15° C. The resulting precipitate was filtered and washed with 3 L of water then air dried to a constant weight (384 g). The wet cake was carried into Example 6 without further drying. P chem: Data recorded from a 3:1 isomeric mixture. TLC Rf =0.19 (75:25 hexane:ethyl acetate); IR (CHCl3) 3605, 3590, 3015, 3000, 2960, 2910, 1608, 1522, 1484, 1352, 1240, 1042 cm-1 ; 1H NMR (CDCl3, 300 MHz) δ (major isomer) 8.16 (d, 2H, J=6.9 Hz), 7.73 (d, 2H, J=6.9 Hz), 6.55 (s, 1H), 6.38 (s, 1H), 5.86 (s, 1H), 5.83 (s, 1H), 4.38 (M, 1H), 2.70 (m, 2H), 1.39 (d, 3H, J=6.3 Hz); d (minor isomer) 8.27 (d, 2H, J=8.9 Hz), 7.90 (d, 2H, J=8.6 Hz), 6.87 (s, 1H), 6.73 (s, 1H), 6.03 (s, 1H), 6.02 (s, 1H), 3.95 (m, 1H), 2.7 (obscured, m, 2H), 1.24 (d, 3H, J=6.1 Hz); mass spectrum, m/z (FD, M+) 329; Anal. Calcd. for C17H15NO6 : C, 62.01; H, 4.59; N, 4.25. found C, 62.22, H, 4.79; N, 4.29.
