Hydrochloric Acid → (4S,5S)-2-(4-bromobenzyl)-5-[(tert-butoxycarbonyl)amino]-4-{[tert-butyl(dimethyl)silyl]oxy}-6-phenylhexanoic Acid

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Reaction Conditions

Reaction Steps

A solution containing the product from Example 92B (18.4 g) in dioxane (190 mL) was treated with sodium hydroxide solution (45 mL, 1N) for 1 hour at 25° C. The mixture was cooled to 0° C., and acidified to pH 5 using 4N HCl, and concentrated under reduced pressure. The concentrate was partitioned between chloroform and water. The organic phase layer was washed with brine, dried over MgSO4, and concentrated. A solution of the residue (22 g) in dioxane (115 mL) was treated with imidazole (19 g, 279 mmol) and t-butyldimethylsilyl chloride (35 g, 232 mmol), stirred at 25° C. for 18 hours and concentrated. The residue was combined with ice, acidified with 4N HCl to pH 3, and extracted with ethyl acetate. The organic phase was washed with brine, dried over MgSO4, filtered, and concentrated. A solution of the residue in a mixture of THF (180 mL), acetic acid (180 mL), and water (60 mL) was stirred for 1 hour at 25° C. and concentrated. The residue was chromatographed on silica gel eluting with 0-50% ethyl acetate in chloroform to give the title compound (14.18 g, 60% yield).

Provenance & Evidence