tert-Butanol → N-(tert-Butoxycarbonyl)-3-sulfanyl-L-valine

Participants

Reaction Steps

5.0 G of L-penicillamine (33.6 mmol) was dissolved in 5 ml of water containing 1.3 g of sodium hydroxide (33.6 mmol, 1 eq.). To this was added 10 ml of tert.-butanol. 8.0 G of di-tert.-butylcarbonate (37 mmol, 1.1 eq.) was added dropwise over 30 minutes. The reaction was allowed to proceed at room temperature for 6 hours. The turbid reaction mixture was diluted with 50 ml of water and extracted with hexane (3×50 ml), acidified to pH 3 with solid sodium bisulfate and extracted with ethyl acetate (3×50 ml). The combined ethyl acetate extracts were dried over sodium sulfate and, then, evaporated to dryness, yielding 8.0 g of Boc-L-penicillamine (96%): nmr (CDCl3) 1.45 ppm and 1.57 ppm, over-lapping singlets, t-butyl and beta-dimethyl protons, 4.32 ppm, br. doublet, alpha proton.

Provenance & Evidence