Ammonium Chloride → 1-[2(R)-[1(R)-(benzyloxycarbamoyl)-2-(3,4,4-trimethyl-2,5-dioxo-1-imidazolidinyl)ethyl]-3-cyclopentylpropionyl)piperidine

Participants

Reaction Steps

A solution of 1.10 g of methyl ester from Example 10 and 568 mg of O-benzylhydroxylamine hydrochloride in 7 ml of THF was treated at −20° with 3.5 ml of a 2M i-PrMgCI solution in THF and, after 1 hr. at −20°, treated with a further 1.7 ml of the Grignard reagent. After a further 2½ hrs. at −20° the mixture was treated with ammonium chloride solution and extracted with methylene chloride. The extracts were dried and concentrated. The residue was crystallized from t-butyl methyl ether/hexane and the crystallizate was dried, there being obtained 1-[2(R)-[1(R)-(benzyloxycarbamoyl)-2-(3,4,4-trimethyl-2,5-dioxo-1-imidazolidinyl)ethyl]-3-cyclopentylpropionyl)piperidine VII, m.p. 135-137°.

Provenance & Evidence