title: Asymmetric synthesis of four diastereomers of 3-hydroxy-2,4,6-trimethylheptanoic acid: proof of configurational assignment.
abstract: Four unique diastereomers of 3-hydroxy-2,4,6-trimethylheptanoic acid--(2R,3R,4R), (2S,3R,4R), (2S,3R,4S), and (2R,3R,4S)--the fatty acid component of callipeltin A and D, have been synthesized from commercially available (+)- and (-)-pseudoephedrine propionamide in 6 steps and 59% average overall yield. Comparison of the 1H and 13C NMR and optical rotation data of the resulting isomers with the natural fragment unambiguously verifies the configurational assignment of the natural isomer as (2R,3R,4R).
mesh_terms: D047630:Depsipeptides; D006538:Heptanoic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry; D010456:Peptides, Cyclic / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D047630:Depsipeptides; D006538:Heptanoic Acids; D010446:Peptide Fragments; D010456:Peptides, Cyclic; C418139:callipeltin A; C470816:callipeltin D