Hydrochloric Acid → (2S,4R)-4-amino-5-biphenyl-4-yl-2-hydroxymethyl-2-methyl-pentanoic acid 1-cyclohexyloxycarbonyloxy-ethyl ester

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Reaction Steps

1-Chloroethyl cyclohexyl carbonate (240 mg, 1.2 mmol) was added to a mixture of (2S,4R)-5-biphenyl-4-yl-4-t-butoxycarbonylamino-2-hydroxymethyl-2-methyl-pentanoic acid (300 mg, 726 μmol) and Et3N (106 μL, 762 μmol) in acetone (10 mL). The mixture was refluxed for 24 hours and the reaction monitored for completion. The individual isomers were separated (˜1:1) and purified (Interchim reverse phase chromatography column) the solvent was removed under vacuum. MeCN (2 mL) and 4 M HCl in 1,4-dioxane (3 mL, 10 mmol) was added and the resulting mixture was stirred for 30 minutes. The solvent was evaporated under vacuum and the product was azeotroped with toluene (1×) to yield (2S,4R)-4-amino-5-biphenyl-4-yl-2-hydroxymethyl-2-methyl-pentanoic acid 1-cyclohexyloxycarbonyloxy-ethyl ester.

Provenance & Evidence