Cyclohexane → tert-butyl (2R)-2-ethynylpyrrolidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

Tert-butyl (2R)-2-(2,2-dibromovinyl)pyrrolidine-1-carboxylate (Intermediate XXXVIII, 8.1 g, 22.8 mmol) was dissolved in dry THF (200 mL) and cooled to −78° C. Then added sec-butyllithium 1.4M in cyclohexane (32.6 mL, 45.6 mmol) over 30 minutes and continued mixing an additional 30 minutes before quenching with 20% ammonium chloride solution (200 mL). The mixture was warmed to rt and diluted with ethyl ether (200 mL). The organic phase was separated, washed with brine, dried in vacuo and purified on a silica gel column using a 100% to 99:1 gradient of methylene chloride to methanol as mobile phase to yield pure tert-buty (2R)-2-ethynylpyrrolidine-1-carboxylate. LC-MS m/z (minus t-butyl+1)=220. 1H NMR (CD3OD, 400 Mhz) 4.44 ppm (s, 1H), 3.44-3.37 (m, 1H), 3.34-3.25 (m, 1H), 2.61 (s, 1H), 2.08-1.85 (m, 4H), 1.47 (s, 9H).

Provenance & Evidence