94226-59-2Relevant academic research and scientific papers
Trading N and O. Part 2: Exploiting aziridinium intermediates for the synthesis of β-hydroxy-α-amino acids
Davies, Stephen G.,Fletcher, Ai M.,Frost, Aileen B.,Roberts, Paul M.,Thomson, James E.
, p. 5849 - 5862 (2015/03/30)
The β-hydroxy-α-amino acids (S,S)-allo-threonine, (S,S)-β-hydroxyleucine and a range of aryl substituted (S,S)-β-hydroxyphenylalanines were prepared from the corresponding enantiopure anti-α-hydroxy-β-amino esters via a rearrangement protocol, which proceeds via the intermediacy of the corresponding aziridinium ions. The starting anti-α-hydroxy-β-amino esters were prepared in >99:1 dr using our diastereoselective aminohydroxylation procedure, whereby conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide to an α,β-unsaturated ester is followed by oxidation of the resultant enolate with (-)-camphorsulfonyloxaziridine. Subsequent activation of the hydroxyl group within the anti-α-hydroxy-β-amino esters promoted aziridinium ion formation [which proceeds with inversion of configuration at C(2)], and regioselective ring-opening of the intermediate aziridinium ions with H2O [which proceeds with inversion of configuration at C(3)] gave the corresponding anti-β-hydroxy-α-amino esters as single diastereoisomers (>99:1 dr). Deprotection of these substrates via sequential hydrogenolysis and ester hydrolysis gave the corresponding β-hydroxy-α-amino acids in good yield and high diastereoisomeric and enantiomeric purity.
DIBENZYLAMINOACETATES AS USEFUL SYNTHETIC EQUIVALENTS OF GLYCINE IN THEi SYNTHESIS OF α-AMINO-β-HYDROXYACIDS
Guanti, Giuseppe,Banfi, Luca,Narisano, Enrica,Scolastico, Carlo
, p. 3671 - 3684 (2007/10/02)
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).
ACID CATALYSIS IN ALDOL CONDENSATION OF α-AMINO SILYLKETENE ACETALS. DIASTEREOSELECTIVE SYNTHESIS OF α-AMINO-β-HYDROXYACIDS.
Guanti, Giuseppe,Banfi, Luca,Narisano, Enrica,Scolastico, Carlo
, p. 3517 - 3520 (2007/10/02)
The aldol-type condensation between α-dibenzylamino trimethylsilyl ketene acetals and various achiral and chiral aldehydes in the presence of a Lewis acid furnishes α-amino-β-hydroxyacids in moderate yields with preferential C2-C3 th
DIASTEREOSELECTIVE SYNTHESIS OF α-AMINO-β-HYDROXYACIDS
Guanti, Giuseppe,Banfi, Luca,Narisano, Enrica,Scolastico, Carlo
, p. 4693 - 4696 (2007/10/02)
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.
