tert-Butyl carbamate → tert-Butyl (2E)-but-2-enoylcarbamate

Participants

Reaction Conditions

Reaction Steps

1,1-Dimethylethyl carbamate (5 g, 42.7 mmol) was dissolved in tetrahydrofuran (THF) (100 mL) in a 500 mL 3 necks round bottom flask and cooled at −78° C. under nitrogen. n-Butyl lithium (1.6 M in THF, 26.7 mL, 42.7 mmol) and (2E)-2-butenoyl chloride (4.55 mL, 42.7 mmol) were added in slow successive additions as follow: 1) n-Butyl lithium: 13.4 mL and (2E)-2-butenoyl chloride 2.28 mL; 2) n-Butyl lithium:6.8 mL and (2E)-2-butenoyl chloride 1.14 mL; 3) n-Butyl lithium:3.34 mL and (2E)-2-butenoyl chloride 0.57 mL; 4) n-Butyl lithium: 1.67 mL and (2E)-2-butenoyl chloride 0.28 mL (2×). A five to ten minutes waiting time was observed between each double addition, and the final mixture was stirred for an extra 30 minutes period at −78° C. The temperature was kept below −60° C. during the additions. The reaction mixture was then slowly poured into a stirred saturated NaHCO3 aqueous solution (250 mL). The aqueous layer was extracted with AcOEt (2×250 mL). The combined organic phases were washed with brine (150 mL), dried over MgSO4 and concentrated in vacuovacuo. Purification of the residue by flash chromatography on silica gel (gradient:50 to 100% AcOEt in Hexanes) gave 1,1-dimethylethyl (2E)-2-butenoylcarbamate (2.21 g, 11.93 mmol, 28%) as a white solid.

Provenance & Evidence