Triethanolamine → N-((2R,3S)-3-Amino-2-hydroxy-4-phenylbutyl)-N-(2-methylpropyl)-4-aminobenzenesulfonamide

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Reaction Steps

The compound of formula 3a (100 g), 10% palladium carbon (10 g) and triethanolamine (2 g) were suspended in methanol and then hydrogenated at 40-45° C. for 2 h. After completion of the reaction (TLC monitoring), filtered the reaction mass to remove palladium carbon. cp. HCl (62 mL) was added to the filtrate, heated to reflux and maintained for 2 h. The reaction mass was cooled to ambient temperature, pH of the reaction mass was adjusted to 6.0-7.0 with 20% sodium hydroxide solution. Methanol was distilled off under vacuum at below 50° C. The resultant residue was dissolved in a mixture of isopropyl alcohol (300 mL) and purified water (600 mL) and pH was further adjusted to 9.0-10.0 with 20% sodium hydroxide solution at ambient temperature. The reaction mass was maintained for 10 h, cooled to 0-5° C., filtered and washed with purified water. The wet cake was suspended in isopropyl alcohol (350 mL), heated to reflux, and maintained for 30 min. The reaction mass was cooled to 2-4° C., maintained for 1 h., filtered and washed with isopropyl alcohol. The wet product was air dried to obtain the compound of formula 4 in 71.3 g (yield-95%) with HPLC purity of 99.76%.

Provenance & Evidence