208402-47-5Relevant academic research and scientific papers
Stereoselective synthesis of β-homothreonine and 3-amino substituted carbohydrates
Koerner, Matthias,Findeisen, Matthias,Sewald, Norbert
, p. 3463 - 3464 (2007/10/03)
Both diastereomers of β-homothreonine derivatives and other precursors of 3-amino substituted carbohydrates together with stereo-selectively in position 2 deuterated analogues have been synthesized by 1,4-addition of homochiral nitrogen nucleophiles to γ-alkoxy enoates. The product distribution of the 1,4-addition of lithium amides strongly depends on the nature of the substrate. The configuration can in one case be controlled by the reagent irrespective of the substrate stereochemistry, in other cases the topicity of the addition is complementary to published results.
Tandem protocol for the stereoselective synthesis of different polyfunctional β-amino acids and 3-amino-substituted carbohydrates
Sewald, Norbert,Hiller, Klaus D.,Koerner, Matthias,Findeisen, Matthias
, p. 7263 - 7274 (2007/10/03)
Conjugate addition of homochiral amidocuprates or lithium amides based on (R)-N-(1-phenylethyl)-(trimethylsilyl)amine to α,β-unsaturated esters proceeds stereoselectively and allows the synthesis of β-amino acids. Trapping of the intermediate ester enolate with D2O affords the corresponding deuterated compounds. anti-α-Alkyl-β-amino acids are obtained stereoselectively after transmetalation of the lithium/copper ester enolate to the titanium ester enolate and trapping with carbon electrophiles. Both diastereomers of β-homothreonine, other precursors of 3-amino-substituted carbohydrates, and stereoselectively in position 2 deuterated analogues are formed from enantiomerically pure γ-alkoxy-substituted enoates. The product distribution observed is complementary to published results regarding 1,4- addition to γ-silyloxy-substituted enoates. The anti/syn selectivity can be explained by assuming transition state geometries where the delivery of the nitrogen nucleophile is controlled by lithium 'chelation' between reagent and substrate. In one case the product configuration can be controlled by the reagent irrespective of the substrate stereochemistry, in other cases the topicity of the addition is complementary to published results. For instance, erythro- or threo-configured 2,3-dideoxy-3-aminopentoses are accessible via this route.
