94226-63-8Relevant articles and documents
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.
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
