反应详情

Analogously to Example 21 D) 1)c), 5.0 g (16.37 mmol) of 5(S)-[1(S)-(Boc-amino)-2-phenylethyl]-dihydrofuran-2-(3H)-one [Example 21 D) 1)b)] dissolved in 100 ml of THF are deprotonated at -75° C. with 32.7 ml of lithium bis(trimethylsilyl)amide 1M in THF, and alkylated starting at -75° C. with 2.51 ml (19.6 mmol) of 2,4-difluorobenzylbromide (Aldrich; Milwaukee/USA) (warming up during 2 h up to max. -60° C.). Column chromatography (SiO2, hexane/ethyl acetate 2:1) yields the title compound: TLC Rf (D)=0.5; tRet (I)=17.2 min.

1. temperaturewarming up during 2 h up
2. custom-60° C.