Sodium cyanoborohydride → (S)-3-[(2S,3R,4R,5S)-5-(N-((S)-2-amino-3-methylbutyl)-L-leucyl)amino-2,3,4,6-tetrahydroxyhexanoyl]amino-3-phenylpropionic acid

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Reaction Conditions

Reaction Steps

To a solution of N-tert-butoxycarbonyl-L-valinal (240 mg) and diphenylmethyl (S)-3-[(2S,3R,4R,5S)-2,3,4,6-tetrahydroxy-5-(L-leucyl)aminohexanoyl]amino-3-phenylpropionate (278 mg) in methanol (10 ml) was added sodium cyanoborohydride (63 mg) at 0° C. and the mixture was stirred at 0° C. for 2 hours and at room temperature for 18 hours. After concentration under reduced pressure, the residue was subjected to flush silica gel column chromatography, followed by elution with ethyl acetate-methanol(20:1). The effective fractions were combined and concentrated under reduced pressure. To the residue was added 4N hydrogen chloride solution in ethyl acetate (10 ml) and the whole was stirred at room temperature for 1 hour. Removal of the organic solvent gave a residue, which was passed through a column of DIAION HP-20SS (Mitsubishi kasei corporation), followed by elution with water-acetonitrile. The effective fractions were combined and concentrated under reduced pressure. The residue was recrystallized from methanol-diethylether to afford the title compound (25 mg).

Provenance & Evidence