反応 #6070

反応方程式

maleic anhydride

acetophenone

ethyl acetate

ethyl acetate

water

vinyl bromide

→

title compound

収率 19.5%

Dimethyl 3-bromocyclobutane-1,2-dicarboxylate

収率 19.5%

反応条件

後処理

1. 1
   その他The vessel was sealed
2. 2
   その他purged with nitrogen for 10 min
3. 3
   その他The vessel was then irradiated for 20 h with a 450 Watt medium pressure mercury vapor lamp
4. 4
   濃縮The solution was concentrated in vacuo
5. 5
   workup.DISSOLUTIONthe residue dissolved in 200 mL of methanol which
6. 6
   workup.ADDITIONhad been treated with 1 mL of trimethylsilyl chloride
7. 7
   濃縮concentrated to a brown viscous oil
8. 8
   その他The oil was chromatographed on silica gel (200 g)
9. 9
   洗浄eluted with 20% ethyl acetate in hexane
10. 10
    その他to give a yellow oil
11. 11
    workup.DISTILLATIONThe oil was purified by short-path distillation

実験手順

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).

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