Sodium borohydride → 2-(2-Hydroxy-3-benzyl-5-methyl-cyclohept-4-en-1-yl)-1-oxo-ethyl-valinyl valine methyl ester

Participants

Reaction Steps

To the above keto-peptide (24) (0.44 g) in ethanol (20 mL) with stirring at room temperature was added NaBH4 (69 mg) in one portion. After stirring for 30 min the reaction was quenched by the addition of aqueous 1N HCl (50 mL). The reaction was extracted with ethyl acetate, washed with saturated NaCl, dried over MgSO4 and evaporated to dryness. The title compound was obtained as a mixture of diastereomers by flash chromatography on silica gel eluted with 60% ethyl acetate in n-hexane then by gravity chromatography in the same system. TLC Rf 0.31 and 0.36 (60% ethyl acetate, n-hexane); MS (DCI/NH3) (M+H)+ =487; 1H NMR (CDCl3)δ0.8-1.0(12H, m) Val γ(CH3)2's, 1.7 (3H, s) allylic CH3, 3.72 (3H, s) CO2CH3, 5.18m and 5.08(1H, br s) vinylic CH, 7.30(5H, s) phenyl.

Provenance & Evidence