Acetic Anhydride → cis-4-[(3,5-Bis-trifluoromethyl-benzyl)-formyl-amino]-2-ethyl-6-trifluoromethyl-3,4-dihydro-2H-quinoline-1-carboxylic acid ethyl ester

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Reaction Steps

A solution of cis-4-(3,5-bis-trifluoromethyl-benzylamino)-2-ethyl-6-trifluoromethyl-3,4-dihydro-2H-quinoline-1-carboxylic acid ethyl ester (Example 3E) (2.0 g, 3.65 mmol) in 20 mL of formic acid was treated with acetic anhydride (11.29 g, 111 mmol) and sodium formate (1.25 g, 18.5 mmol). After stirring for 24 h at room temperature, the reaction mixture was diluted with water and extracted with ethyl acetate. The combined organic phases were dried over magnesium sulfate, filtered and concentrated in vacuo to afford the crude product, which was purified by silica gel chromatography using 10-15% ethyl acetate/hexanes as eluent to afford 1.8 g of the title product. MS m/z 571.2 (M+ +1); 1H NMR (~5:1 mixture of formamide rotamers, CDCl3) δ 0.75 (t, 3H), 1.28 (t, 3H), 1.42 (m, 1H), 1.6-1.75 (M, 2H), 2.3 (bm, 1H), 4.15-4.3 (m, 2H), 4.3-4.4 (m, 1H), 4.5-4.7 (bm, 1H), 4.8-5.8 (bm, 2H), 7.14 and 7.08 (s, 1H), 7.5-7.6 (m, 2H), 7.74 (s, 2H), 7.80 and 7.86 (s, 1H), 8.47 and 8.62 (s, 1H).

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