Hydrochloric Acid → methyl 3-methyl-2-[(3S,4R)-3-methyl-2-oxo-4-allylazetidin-1-yl]but-2-enoate

Participants

Reaction Conditions

Reaction Steps

1.55 M Butyl lithium-hexane solution (1.66 ml) was added to a solution of N-isopropylcyclohexylamine (0.29 ml) in tetrahydrofuran (3 ml) at -70° C., and the mixture was stirred for 20 minutes at -70° C. and allowed to warm up to 0° C. This mixture was added to a solution of methyl 3-methyl-2-[(4R)-2-oxo-4-allylazetidin-1-yl]but-2-enoate (100 mg) in tetrahydrofuran (3 ml) at -70° C., and the mixture was stirred for 1 hour at -70° C. and allowed to warm up to -30° C. during 30 minutes. 1 N Hydrochloric acid (3.6 ml) was added to the reaction mixture at -70° C., and the mixture was diluted with ethyl acetate (30 ml). The solution was washed with water and brine, dried over magnesium sulfate, and evaporated in vacuo. The residue was chromatographed on silica gel eluting with a mixture of hexane and ethyl acetate (5:1-2:1) to give methyl 3-methyl-2-[(3S,4R)-3-methyl-2-oxo-4-allylazetidin-1-yl]but-2-enoate (20 mg); IR (CH2Cl2): 1740, 1715 cm-1 ; NMR (CDCl3) δ: 1.23 (d, 3H, J=8 Hz), 1.95 (s, 3H), 2.19 (s, 3H), 1.36 (t, 2H, J=7 Hz), 3.36 (dq, 1H, J=6, 8 Hz), 3.75 (s, 3H), 4.04 (dt, 1H, J=6, 7 Hz), 4.9-5.2 (m, 2H), 5.4-5.9 (m, 2H); and methyl 3-methyl-2-[(3R,4R)-3-methyl-2-oxo-4-allylazetidin-1-yl]but-3-enoate (28 mg); IR (CH2Cl2): 1740 cm-1 ; NMR (CDCl3) δ: 1.27 and 1.29 (a pair of d, 3H, J=8 Hz), 1.83 (broad s, 3H), 2.1-2.9 (m, 2H), 2.85 (dq, 1H, J=2, 8 Hz), 3.2-3.4 (m, 1H), 3.74 and 3.76 (a pair of s, 3H), 4.8-5.2 (m, 5H), 5.5-6.0 (m, 1H); and a mixture of methyl 3-methyl-2-[(3R,4R)-3-methyl-2-oxo- 4-allylazetidin-1-yl]but-2-enoate and methyl 3-methyl-2-[(3S,4R)-3-methyl-2-oxo-4-allylazetidin-1-yl]but-3-enoate (36 mg): IR (CH2Cl2): 1740 cm-1.

Provenance & Evidence