Propionic Acid → 5(S)-[1(S)-(Boc-Amino)-2-(p-benzyloxyphenyl)ethyl]-3(R)-[(p-methoxyphenyl)-methyl]dihydrofuran-2-(3H)-one

Participants

Reaction Steps

In analogy with Example 5d), 2.9 g (7.04 mmol) of 5(S)-[1(S)-(Boc-amino)-2-(p-benzyloxy-phenyl)ethyl]dihydrofuran-2-(3H)-one (preparation, see Example 1g)], dissolved in 10.3 ml of THF and 1.2 ml of DMPU, are deprotonated, at -70° C., with 14.1 ml of a 1 M solution of lithium bis(trimethylsilyl)amide in THF, and alkylated (at from -75° C. to -50° C.), with 2.6 g (10.57 mmol) of p-methoxybenzyl iodide [preparation, see Example 7e)] in 10 ml of THF. Protonation, at -75° C., with 2.6 ml (35.2 mmol) of propionic acid and 2.6 ml of water, extraction and column chromatography (SiO2, hexane/ethyl acetate, 2:1) affords the title compound: TLC Rf (D)=0.48; tRet (II)=18.8 min.

Provenance & Evidence