Triethylamine → Rasagiline

Participants

Reaction Steps

Methanesulfonyl anhydride (3.0 g, 17.2 mmol) as a solution in dichloromethane (8 mL+4 mL) was added to a stirred solution of (S)-1-indanol (1.02 g, 7.6 mmol) and triethylamine (4.4 mL, 31.5 mmol) in dichloromethane (20 mL) at −26° C. (internal, −35° C. external) over 10 minutes. During the addition the internal temperature rose to −20° C. The reaction was maintained at −29° C. (internal, −35° C., external) for 45 minutes before propargylamine (5 mL, 78 mmol) was added over 2 minutes. The reaction was allowed to warm slowly to room temperature overnight before being portioned between ethyl acetate (50 mL) and ice-water (75 mL, pH of solution 9.7). The organic layer was concentrated under reduced pressure to afford a brown oil which was partitioned between methyl tert-butyl ether (50 mL) and aqueous hydrochloric acid (1M, 40 mL, pH of solution <1). The aqueous layer was basified to pH>12.5 by addition of aqueous sodium hydroxide solution (2M, 30 mL) before being extracted with ethyl acetate (50 mL+30 mL). The combined final organic extracts were dried (MgSO4), filtered and concentrated under reduced pressure to afford the title compound as a brown liquid (0.81 g, 68%). Analysis of this material by chiral GC indicated it to be 46% e.e.

Provenance & Evidence