Hydrochloric Acid → Methyl 3-amino-4-(2,4,5-trifluorophenyl)butanoate

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Reaction Steps

The methyl(Z)-3-amino-4-(2,4,5-trifluorophenyl)but-2-enoate (350.0 gm, 1.42 mol) (28) was charged in methanol (10.0 vol, 3.5 Ltr) at 25-30° C. and the reaction was stirred for 10-15 minutes to give a clear solution. To the clear pale yellow solution, controlled addition of sulphuric acid (70.0 ml, 0.2 vol) was done at 0 to −10° C. and the clear solution was stirred for 10-15 minutes at 0 to −10° C. After 10-15 minutes stirring at 0 to −10° C., sodium cyanoborohydride (2.0 eq, 170.0 gm) was charged in 10 lots. The clear white suspension was stirred at 0 to −10° C. for 2 hours. The methanol was distilled completely at 45-50° C. under reduced pressure to give a pale yellow residue. The pale yellow residue was further treated with a 1:1 mixture of 35% hydrochloric acid:water at 0-5° C. to give pH 2. The suspension was stirred at 0-5° C. for 10-15 minutes and the suspension was further basified by using 20% sodium carbonate to give pH 8-9. The product was extracted in ethyl acetate (2×10.0 vol, 2×3.5 Ltr). The combined ethyl acetate layers were washed with water (3×10.0 vol, 3×3.5 Ltr). The product was isolated by distillation of the ethyl acetate to give a pale yellow coloured oil.

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