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New Chiral Auxiliary (new + chiral_auxiliary)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

ChemInform Abstract: New Chiral Auxiliaries for Highly Stereoselective Asymmetric Methoxyselenenylations.

CHEMINFORM, Issue 1 2001
Thomas G. Back
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

1-(2,4,6-Triisopropylphenyl)ethylamine: A New Chiral Auxiliary for the Asymmetric Synthesis of ,-Amino Acid Derivatives.

CHEMINFORM, Issue 21 2007
Pascale Cividino
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

1-(,-Aminobenzyl)-2-naphthol: A New Chiral Auxiliary for the Synthesis of Enantiopure ,-Aminophosphonic Acids

CHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2009
Kirill
Abstract Ooh Betti! A new diastereoselective synthesis of ,-aminophosphonates has been developed based on the reaction of trialkyl phosphites with chiral imines derived from (R)- or (S)-1-(,-aminobenzyl)-2-naphthol (Betti base; see scheme, X=H, CH3, or Br). The reaction proceeds with high diastereoselectivity. Treatment with HCl results in the formation of the desired ,-aminophosphonic acids. A new diastereoselective synthesis of ,-aminophosphonates has been developed, based on the reaction, in the presence of trifluoroacetic acid, of trialkyl phosphites with chiral imines derived from (R)- or (S)-1-(,-aminobenzyl)-2-naphthol. The reaction proceeds at room temperature in toluene with high diastereoselectivity. The major diastereomer can be separated by crystallization from an appropriate solvent. The relative configuration of both chiral centers of the major diastereomer was determined by single-crystal X-ray structure analysis. The desired ,-aminophosphonic acids can be obtained in enantiopure form by treatment of the corresponding diastereomers with HCl. [source]

Asymmetric Desymmetrization Based on an Intramolecular Haloetherification: A Highly Effective and Recyclable Chiral Nonracemic Auxiliary, 2- exo -Methyl-3- endo -phenyl-5-norbornene-2-carboxaldehyde, for meso -1,3- and meso -1,4-Diols

CHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2004
Hiromichi Fujioka Prof. Dr.
Abstract A new chiral auxiliary, a 3- endo -phenyl norbornene aldehyde derivative, which is a crystalline, very stable, and easily handled, was developed for the desymmetrization of meso -1,3- and meso -1,4-diols. The key step of the method, an intramolecular bromoetherification, proceeded in a highly diastereoselective manner. A four-step sequence, 1) acetalization, 2) intramolecular bromoetherification followed by acid hydrolysis, 3) protection of the alcohol, and 4) retrobromoetherification, transformed the meso -diols into optically active derivatives. The 3- endo -phenyl norbornene aldehyde derivative was simultaneously reformed and could be used repeatedly. This is the first chemical example of a single auxiliary that is applicable for highly enantioselective desymmetrization of meso -1,3- and meso -1,4-diols; to the best of our knowledge, this is the best chemical method available for the desymmetrization of meso -1,4-diols. [source]