反应详情

A solution of 5 g (51 mmol) of maleic anhydride and 0.5 mL (4 mmol) of acetophenone in 50 mL of ethyl acetate was added to a 100 mL pyrex photochemical reaction vessel. The vessel was sealed and purged with nitrogen for 10 min then cooled with tap water while 13.8 g (129 mmol) of vinyl bromide was being added to the ethyl acetate solution. The vessel was then irradiated for 20 h with a 450 Watt medium pressure mercury vapor lamp. The solution was concentrated in vacuo and the residue dissolved in 200 mL of methanol which had been treated with 1 mL of trimethylsilyl chloride. The solution was stirred at ambient temperature overnight and then concentrated to a brown viscous oil. The oil was chromatographed on silica gel (200 g) eluted with 20% ethyl acetate in hexane to give a yellow oil. The oil was purified by short-path distillation using a 1" fractionating column to give 2.5 g (19.5% yield) of the title compound; b.p. 75°-80° C. (0.1 mm Hg); EI-MS, m/e (rel intensity): 220 (M+ --CH3O, 60), 218 (60), 192 (42), 190 (39), 171 (100); 1H NMR (CDCl3) δ2.60 (m, 1H), 2.82 (m, 1H), 3.56 (td, 1H), 3.72 (m, 6H), 3.94 (t, 0.4H), 4.12 (q, 0.6H), 4.93 (q, 1H).

1. customThe vessel was sealed
2. custompurged with nitrogen for 10 min
3. customThe vessel was then irradiated for 20 h with a 450 Watt medium pressure mercury vapor lamp
4. concentrationThe solution was concentrated in vacuo
5. dissolutionthe residue dissolved in 200 mL of methanol which
6. additionhad been treated with 1 mL of trimethylsilyl chloride
7. concentrationconcentrated to a brown viscous oil
8. customThe oil was chromatographed on silica gel (200 g)
9. washeluted with 20% ethyl acetate in hexane
10. customto give a yellow oil
11. distillationThe oil was purified by short-path distillation