A stereoselective synthesis of (2S,4R)-δ-hydroxyleucine methyl ester: a component of cyclomarin A

(2S,4R)-δ-Hydroxyleucine methyl ester, the N-demethyl analogue of an amino acid contained within the macrocycle of cyclomarin A, was successfully synthesized using Davis’ asymmetric Strecker reaction.

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(S)-4-Benzyl-3-((R)-2-methylpent-4-enoyl)oxazolidin-2-oneC16H19O3NEe > 95%[α]D20=+98.0 (c 0.9, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (4′S,3R)

(R)-2-Methylpent-4-en-1-olC6H12OEe > 95%[α]D20=-1.8 (c 0.4, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

(R)-((2-Methylpent-4-enyloxy)methyl)benzeneC13H19OEe > 95%[α]D20=-1.6 (c 1.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

(R)-Benzyl 2-methyl-4-oxobutanoateC12H14O3Ee > 95%[α]D20=+0.7 (c 0.9, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

(R)-4-(Benzyloxy)-3-methylbutanalC12H16O2Ee > 95%[α]D20=+8.9 (c 0.7, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

(Ss,3R)-(+)-4-(Benzyloxy)-3-methylbutylidene-p-toluenesulfinamideC19H23O2NSEe > 95%[α]D20=+37.0 (c 4.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (Ss,3R)

(Ss,2S,4R)-(+)-N-(p-Toluenesulfinyl)-2-amino-5-(benzyloxy)-4-methylpentanenitrileC20H24O2N2SEe > 95%[α]D20=+10.7 (c 0.7, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (Ss,2S,4R)

(2S,4R)-2-Amino-5-(benzyloxy)-4-methylpentanenitrileC13H18ON2Ee > 95%[α]D20=+8.0 (c 0.6, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,4R)

(2S,4R)-Methyl 2-amino-5-(benzyloxy)-4-methylpentanoateC14H21O3NEe > 95%[α]D20=-36.0 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,4R)