反应详情

A solution of 5-methoxypyrrolidin-2-one (34) (2.55 g, 33.3 mmol), propargyl trimethylsilane (3.77 g, 33.7 mmol) and CH2Cl2 (100 mL) was cooled to 0° C. To this solution was added TiCl4 (4.9 mL, 44.4 mmol) in CH2Cl2 (20 mL) over a 15 min period at ≤3° C. After stirring for 30 min, the reaction was poured through silica gel (30 g), rinsed with CH2Cl2 (100 mL), and this initial filtrate (120 mL) discarded. The silica gel was then washed with 5% MeOH/CH2Cl2 (100 mL) followed by 10% MeOH/CH2Cl2 (100 mL), and the combined filtrates were washed with water (50 mL). The aqueous layer was back extracted with CH2Cl2 (4×30 mL), and the combined organic layers dried over MgSO4 and rotary evaporated (≤30° C.) to give 5-(1,2-propadienyl)-2-pyrrolidinone (35) as a brown oil: TLC (Eluant A) Rf =0.45; 1H NMR: δ6.6 (br s, 1 H, NH); 5.17 (ddd, 3J64 ≃4J68 ≃4J68 ≃6.6 Hz, 1 H, H6); 4.88 (d, 4J68' =6.4, 1 H, H8'); 4.21 (m, 1 H, H5); 2.35 (m, 3 H, H3, H4, H4'); 1.93 (m, 1 H, H3'); Cl Mass spec: m/z 124 (MH+), 84 (MH+ --C3H4).

1. additionthe reaction was poured through silica gel (30 g)
2. washrinsed with CH2Cl2 (100 mL)
3. washThe silica gel was then washed with 5% MeOH/CH2Cl2 (100 mL)
4. washthe combined filtrates were washed with water (50 mL)
5. extractionThe aqueous layer was back extracted with CH2Cl2 (4×30 mL)
6. dry with materialthe combined organic layers dried over MgSO4
7. customrotary evaporated (≤30° C.)