530113-21-4Relevant articles and documents
Synthesis of enantiopure (αMe)Dip and other α-methylated β-branched amino acid derivatives
Avenoza, Alberto,Busto, Jesus H.,Cativiela, Carlos,Peregrina, Jesus M.,Sucunza, David,Zurbano, Maria M.
, p. 399 - 405 (2007/10/03)
This report describes the synthesis of the two enantiomerically pure α-methylated β-branched phenylalanine derivatives, (S)- and (R)-α-methyl-β,β-diphenylalanine - (αMe)Dip - starting from the chiral building blocks (R)- and (S)-N-Boc-N,O-isopropylidene-α
Asymmetric Syntheses via Heterocyclic Intermediates, X. - Enantioselective Synthesis of (2R)-2-Methylserines
Schoellkopf, Ulrich,Groth, Ulrich,Hartwig, Wolfgang
, p. 2407 - 2418 (2007/10/02)
Aldehydes and ketones react with the lithiated bislactim ether 3 of cyclo-(L-Ala-L-Ala) with 81 to >95percent asymmetric induction (d.e. = diastereomeric excess) at C-3; (R) configuration is formed predominantly. - A model concept for the asymmetric induction is proposed. - With aldehydes or unsymmetrical ketones C-7 of the adducts 6 becomes a chiral center, too. (R) configuration is induced here with d. e. 47 - 73percent.Hydrolysis of the addition products 6 (0.25 N HCl, room temperature) gives L-Ala-OCH3 and (2R)-2-methylserine methyl esters 7.Both compounds can be separated either at the ester stage by distillation or - if 7 is thermolabile - after further hydrolysis at the amino acid stage.
