101055-56-5Relevant articles and documents
Alternative Method for the Resolution of 1-Benzoyl-2-tert-butyl-3-methyl-1,3-imidazolidin-4-one
Juaristi, Eusebio,Rizo, Benito,Natal, Vicente,Escalante, Jaime,Regla, Ignacio
, p. 821 - 826 (2007/10/02)
The title heterocycles, which are useful chiral precursors for the asymmetric synthesis of α-amino acids, an be prepared in enantiomerically pure form via the separation of diastereomeric derivatives incorporating (S)-α-methyl-benzylamine.
RESOLUTION AND USE IN α-AMINO ACID SYNTHESIS OF IMIDAZOLIDINONE GLYCINE DERIVATIVES
Fitzi, Robert,Seebach, Dieter
, p. 5277 - 5292 (2007/10/02)
The imidazolidinones (rac.-1 and rac.-2) obtained from pivalaldehyde and glycine amides are resolved efficiently by crystallization of diastereomeric ammonium salts with chiral acids (mandelates and a gulonate respectively).The free bases are acylated under Schotten-Baumann conditions to give enantiomerically pure 1-Bz-, 1-BOC-, 1-Z- or 1-formyl-2-t-butyl-3-methyl- or -3-benzyl-4-imidazolidinones.Diastereoselective alkylation of the 3-methyl derivatives (BMI) with a variety of electrophiles (LDA/THF -70 to +25 degC) gives trans-disubstituted imidazolidinones exclusively (3-22).Some of these are hydrolyzed by a procedure employing excess acidic ion exchange resin to give enantiomerically pure (R)- or (S)-amino acids.The procedure is compared with other methods of generating chiral glycine enolates.
Addition of Chiral Glycine, Methionine, and Vinylglycine enolate Derivatives to Aldehydes and Ketones in the Preparation of Enantiomerically Pure α-Amino-β-hydroxy Acids
Seebach, Dieter,Juaristi, Eusebio,Miller, David D.,Schickli, Christof,Weber, Theodor
, p. 237 - 261 (2007/10/02)
Chiral enolates of imidazolidinones and oxazolidinones from the title amino acids react with carbonyl compounds to afford the corresponding alcohols in excellent yields (see Scheme 5).Furthermore, the addition to aldehydes proceeds with high diastereoselectivity to give, after acid hydrolysis, threo-α-amino-β-hydroxy acids of high enantiomeric purity.Some of the threo-α-amino-β-hydroxy acids prepared in this work are the proteinogenic (S)-threonine (26), the naturally occuring (S)-3-phenylserine (28), and (S)-3-hydroxyleucine (27) as well as the unnatural (S)-4,4,4-rtifluorothreonine (30) and (S)-3-(4-pyridyl)serine (31).The N-methylamide of (2S,3R,4R,6E)-3-hydroxy-4-methyl-2-(methylamino)-6-octenoic acid (32), the uniqe amino acid in the immunosuppressive cyclosporine, was prepared by the new method.This report presents also information suggesting that both steric and stereoelectronic effects are responsible for the good stereoselectivities observed.
Methionine as Precursor for the Enantioselective Synthesis of α-Branched Vinylglycines and of Other Amino Acids
Weber, Theodor,Aeschimann, Roland,Maetzke, Thomas,Seebach, Dieter
, p. 1365 - 1377 (2007/10/02)
Methionine is converted by previously published methods into the diastereoisomerically pure 3-thiabutyl-substituted oxazolidinone (7) and imidazolidinones 5 and 6.An X-ray crystal structure determination of cis-3-benzoyl-2-(tert-butyl)-4-(3-thiabutyl)oxaz