反应详情

A solution of n-butyl lithium in hexane (1.6 M, 7.7 ml) was added dropwise under nitrogen with stirring to a suspension of 2-(1-pyrrolidyl)ethyltriphenylphosphonium bromide (5.41 g) in dry THF (75 ml) keeping the temperature at -10° to -5°. The addition was complete after 5 min. The mixture was then stirred at 0° for 20 min. then cooled to -5° and treated with a solution of (1-ethoxymethylimidazol-2-yl)-4-methylphenylmethanone (3.0 g) in dry THF (30 ml). The mixture was stirred at room temperature for 16 h. and then the precipitated triphenylphosphine oxide was filtered off and washed with a little THF (10 ml). The filtrate and washings were combined and concentrated in vacuo to a yellow syrup. This was absorbed from chloroform (3 ml) onto a column of silica gel (Merck Kieselgel 60, 200 g). Removal of the solvent afforded isomers of the title compound as a thick yellow brown syrup (3.52 g) which was used in the next stage without further purification.

1. customat -10° to -5°
2. additionThe addition
3. temperaturethen cooled to -5°
4. stirringThe mixture was stirred at room temperature for 16 h.
5. filtrationthe precipitated triphenylphosphine oxide was filtered off
6. washwashed with a little THF (10 ml)
7. concentrationconcentrated in vacuo to a yellow syrup
8. customThis was absorbed from chloroform (3 ml) onto a column of silica gel (Merck Kieselgel 60, 200 g)
9. customRemoval of the solvent