HCID 57011577, compound → (2S,4R)-2-(tert-butoxycarbonyl)amino-4-(benzyloxymethyl)-5-methyl-hexanoic acid methyl ester

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Reaction Steps

(2S,3S,5R)-2-[3-(tert-Butoxycarbonyl)amino-5-(benzyloxymethyl)-2-hydroxy-6-methylheptyl]-N-(butyl)acrylamide (A) and (2R,3S,5R)-2-[3-(tert-butoxycarbonyl)amino-5-(benzyloxymethyl)-2-hydroxy-6-methylheptyl]-N-(butyl)acrylamide (B): In a manner analogous to that described in Example 1g), there is obtained first, by reduction of (2S,4R)-2-(tert-butoxycarbonyl)amino-4-(benzyloxymethyl)-5-methyl-hexanoic acid methyl ester (8.0 g), dissolved in anhydrous toluene (120 ml), with a 1.2M diisobutylaluminium hydride solution in toluene (34.9 ml), (2S,4R)-2-(tert-butoxycarbonyl)amino-4-(benzyloxymethyl)-5-methyl-hexanal in the form of a pale-yellow oil (Rf (N)=0.6). The crude aldehyde is reacted in a manner analogous to that described in Example 1g) without being purified further. The crude product (14.8 g) obtained after aqueous working-up is chromatographed over 1.0 kg of silica gel using an eluant gradient from B to E, with separation of the two (2S,3S,5R)- and (2R,3S,5R)-diastereoisomers. There are obtained title compound A (2.52 g, 24%) in the form of a light-yellow oil, Rf (E)=0.55, HPLC Rt =19.8 min, MS(FAB) m/e 491 (M+ +1), and title compound B (3.76 g, 35%) in the form of a light-yellow oil, Rf (E)=0.42, HPLC Rt =19.6 min. MS(FAB) m/e 491 (M+ +1).

Provenance & Evidence