反应详情

Under Ar-atmosphere, to a solution of ethyl phenylacetate (42.4 g, 0.26 mol) and DMPU (5 mL) in THF (250 mL) was added dropwise a solution of LDA (2 M, 135 mL, 0.27 mol) at −78° C. The mixture was stirred for 2 h, before methyl iodide (41.40 g, 0.29 mol) was added in a single portion. The mixture was stirred overnight and allowed to warm to room temperature. After cooling to −78° C., 1,3-dibromopropane (72.7 g, 0.36 mol) was added and the mixture was allowed to stir overnight, gradually warming to room temperature. The mixture was hydrolyzed by consecutive addition of ice (200 g), saturated aqueous NH4Cl solution (400 mL), and concd HCl (100 mL), and extracted with ethyl acetate (2×200 mL). The organic layers were dried over anhydrous MgSO4, and distilled under vacuum to give 205b as colorless oil (88.6 g, 59%). Bp 123-128° C./0.25 mmHg. 1H NMR (CDCl3): 7.20-7.10 (m, 5 H), 4.12 (q, 2 H, J=7.2), 3.35 (t, 2 H, J=6.9), 2.18-2.00 (m, 2 H), 1.77-1.72 (m, 2 H), 1.56 (s, 3 H), 1.18 (t, 3 H, J=6.9). 13C NMR (CDCl3): 175.9, 143.4, 128.5, 126.9, 126.0, 61.0, 49.8, 38.2, 34.0, 28.5, 22.8, 14.2.

1. additionwas added in a single portion
2. temperatureAfter cooling to −78° C.
3. stirringto stir overnight
4. temperaturegradually warming to room temperature
5. extractionextracted with ethyl acetate (2×200 mL)
6. dry with materialThe organic layers were dried over anhydrous MgSO4
7. distillationdistilled under vacuum