(2s)-2-Aminopentane-1,5-diol → (3S,6S)-3-(3-Hydroxy-propyl)-6-methyl-5-oxo-hexahydro-oxazolo[3,2-a]pyrazine-7-carboxylic acid benzyl ester

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Reaction Steps

Condensation of (S)-2-[benzyloxycarbonyl-(2-oxo-ethyl)-amino]-propionic acid methyl ester (intermediate 1) with (S)-2-amino-pentane-1,5-diol in analogy with examples 1/2F produced a nearly statistical mixture of the title compound [light yellow gum, MS: 349.3 (M+H)+] and (3S,5S)-5-hydroxymethyl-3-methyl-4-oxo-octahydro-9-oxa-2,4a-diaza-benzocycloheptene-2-carboxylic acid benzyl ester [light yellow gum, MS:349.3 (M+H)|], which were separated by column chromatography (SiO2; DCM→DCM/MeOH/25% aq. ammonia solution 90:10:0.25).

Provenance & Evidence