Hydrochloric Acid → (R)-3-Hydroxy-4-methyl-3-(2-phenyl-ethyl)-pentanoic Acid

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Reaction Steps

The mother liquor from the isolation of diastereomeric salt G-10 (S) was treated with 1N HCl and extracted with EtOAc. The organic phase was washed with brine, dried (MgSO4), filtered and concentrated to liberate the free β-hydroxy acid. HPLC analysis indicated the isolated material was 73% (R):27% (S). β-Hydroxy acid G-10 (1 equiv.) was dissolved in 600 mL EtOAc and treated with (R)-α-methylbenzylamine (0.74 equiv.). The resulting suspension was placed on a steam bath and heated to reflux. The solution was allowed to cool to room temperature slowly and then cooled to 0° C. in an ice bath. The resulting solids were filtered off and washed with cold EtOAc followed by Et2O to yield the title compound. The free acid was obtained by treating the salt with 1N HCl followed by extraction with EtOAc. The organic phased was washed with brine, dried (MgSO4), filtered and concentrated to afford the resolved β-hydroxy acid. HPLC analysis of isolated solid (as the free acid): (OD chiralpak column, 1 mL/min., 97.5% Hexanes:2.5% IPA:+0.1% Formic acid)

Provenance & Evidence