反应详情

In analogy with Example 5d), 5.55 g (13.5 mmol) of 5(S)-[1(S)-(Boc-amino)-2-(p-benzyloxyphenyl)ethyl]dihydrofuran-2-(3H)-one [preparation, see Example 1g)], dissolved in 20 ml of THF and 2.3 ml of DMPU, are deprotonated, at -70° C., with 27 ml of a 1 M solution of lithium bis(trimethylsilyl)amide in THF, and alkylated (1 h) with 5.0 g (20.2 mmol) of 4-biphenylylmethyl bromide (Salor, Milwaukee, USA) in 16 ml of THF. Protonating with 5 ml (67.4 mmol) of propionic acid and 5 ml of water, at -75° C., extracting and medium pressure chromatography (gradient: 30-50% ethyl acetate in toluene) results in the title compound: TLC Rf (Q)=0.15; tRet (II)=20.0 min.

1. customalkylated (1 h)