DIBENZYLAMINOACETATES AS USEFUL SYNTHETIC EQUIVALENTS OF GLYCINE IN THEi SYNTHESIS OF α-AMINO-β-HYDROXYACIDS
The stereochemical course of three new simple methodologies for the preparation of α-amino-β-hydroxyacids starting from dibenzylaminoacetates as synthetic equivalents of glycine is described.While the aldol-type condensation via lithium enolates gave results highly dependent on the aldehyde employed, producing in some cases diastereoselectivities up to 5:1 for the anti isomers, the acid-catalysed aldol condensation of silyl ketene acetals yielded predominantly syn adducts with selectivities from 5:1 to 32:1.Finally the acylation-reduction procedure gave the best results in terms of yields and stereoselectivities, affording syn isomers with excellent induction ( 13:1).
Guanti, Giuseppe,Banfi, Luca,Narisano, Enrica,Scolastico, Carlo
p. 3671 - 3684
(2007/10/02)
DIASTEREOSELECTIVE SYNTHESIS OF α-AMINO-β-HYDROXYACIDS
threo-α-Dibenzylamino-β-hydroxyesters (2) have been synthesised with high diastereoselectivity through the reduction of α-dibenzylamino-β-oxoesters (4) and then transformed into threo-α-amino-β-hydroxyacids.
Guanti, Giuseppe,Banfi, Luca,Narisano, Enrica,Scolastico, Carlo
p. 4693 - 4696
(2007/10/02)
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