Acetic Acid → 1-Benzyl 4-tert-butyl (2R)-2-(hydroxymethyl)piperazine-1,4-dicarboxylate

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Reaction Steps

To (S)-1-(benzyloxycarbonyl)4-(tert-butyloxycarbonyl)-piperazine-2-carboxylic acid (15.2 g, 0.04 mol) in tetrahydrofuran (200 ml) at 0° C. under argon was added borane (1M soln. in THF; 111 ml, 0.11 mol) dropwise over 15 min. The resulting mixture was stirred for 1 h, maintaining the temperature between 0° C. and 5° C., and then allowed to reach room temperature and stirred a further 18 h. The mixture was then carefully added, with stirring, to 5% g. acetic acid in water (1 l). After 1 h, the organics were evaporated in vacuo and the residual aqueous extracted with ethyl acetate (300 ml×4). The combined extracts were dried (Na2SO4), and evaporated in vacuo to a colourless oil. Chromatography on silica gel eluting with ethyl acetate-hexane mixtures afforded the title product (11 g, 75%) as a colourless oil.

Provenance & Evidence