1,8-Diazabicyclo(5.4.0)undec-7-ene → Ethyl 3-methyl-1H-pyrrole-2-carboxylate

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Reaction Steps

Pyrroline 83 (8.80 g, 28.48 mmol) was dissolved in THF (70 mL). DBU (9.78 mL, 65.50 mmol) was added dropwise and the resulting solution stirred under reflux overnight. The mixture was cooled to room temperature, diluted with ether and washed with 5% aq. HCl, 5% sodium bicarbonate solution and water. The organic layer was dried over sodium sulfate, filtered and evaporated under reduced pressure to give the crude solid 84 (4.30 g, 98%). 1H-NMR (400 MHz, CDCl3): δ 1.37 (t, 3H), 2.35 (s, 3H), 4.31 (q, 2H), 6.08 (d, 1H), 6.81 (d, 1H), 8.90 (s broad, 1H) ppm. 13C-NMR (100 MHz, CDCl3): δ □ 12.76, 14.53, 59.96, 112.58□, 119.35, 121.53, 127.96, 162.01 ppm. DEPT (100 MHz, CDCl3): CH3 carbons: 12.76, 14.53; CH2 carbons: 59.96; CH carbons: 112.58, 121.53 ppm. LC/MS: 90.74%, m/z=153.

Provenance & Evidence