反应详情

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.

1. temperaturemaintaining the temperature between 0° C. and 5° C.
2. customto reach room temperature
3. stirringstirred a further 18 h
4. additionThe mixture was then carefully added
5. stirringwith stirring, to 5% g
6. waitAfter 1 h
7. customthe organics were evaporated in vacuo
8. extractionthe residual aqueous extracted with ethyl acetate (300 ml×4)
9. dry with materialThe combined extracts were dried (Na2SO4)
10. customevaporated in vacuo to a colourless oil