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Diastereoselective Reactions (diastereoselective + reaction)

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Chemistry100%

Selected Abstracts

Diastereoselective Reaction of [1-(2,4,6-Triisopropylphenylsulfinyl)-2-naphthyl]methanimines via Diastereomeric Rotamers.

CHEMINFORM, Issue 3 2003
Shuichi Nakamura
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Diastereoselective Reactions of the Tiglic Acid Functionality Mediated by Oxazolidine Chiral Auxiliaries: A Mechanistic Comparison of DMD andm -CPBA Epoxidations versus Singlet Oxygen and PTAD Ene Reactions

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2005
Aurelia Pastor
Abstract 2,2-Dimethyloxazolidines have been utilized as chiral auxiliaries for the diastereoselective functionalization of the optically active tiglic acid derivatives (S)- 1 by means of epoxidation with DMD or m -CPBA and ene reactions with 1O2 or PTAD. In the DMD and m -CPBA epoxidations, high diastereoselectivities but opposite senses of diastereomer selection were observed. In contrast, the stereochemistry of the 1O2 and PTAD ene reactions depended on the size of the attacking enophile: whereas essentially perfect diastereoselectivity was obtained with PTAD, much lower stereoselection was observed with 1O2. The stereochemical results for the DMD and m -CPBA epoxidations and the PTAD ene reaction are explained in terms of the energy differences for the corresponding diastereomeric transition states, dictated by steric and electronic effects. The PTAD ene reaction for these tiglic acids (S)- 1 provides, after removal of the chiral auxiliaries, an attractive synthetic route for optically active ,-amino acid derivatives.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

ChemInform Abstract: Generation of Hafnium Hydride and Its Application to Chemo- and Diastereoselective Reactions.

CHEMINFORM, Issue 43 2009
Ikuya Shibata
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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Gold Catalysis: Efficient 1,3-Induction with Diastereotopic Homopropargyl Alcohols in the Phenol Synthesis

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009
A. Stephen
Abstract Furans with diastereotopic alkynyl groups were prepared and then converted to anellated phenols in gold-catalyzed reactions. In all cases a highly diastereoselective reaction was observed. The stereochemical outcome of the 1,3-induction could be assigned by two independent crystal structure analyses, showing a cis -arrangement of the two alkyl substituents on the benzoanellated cyclohexene ring. [source]

Highly Stereoselective Synthesis of Novel Multistereogenic Bis - Bifunctional Ligands Based on [2.2]Paracyclophane- 4,7-quinone, their Structure Elucidation and Application in Asymmetric Catalysis

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2005
Natalia Vorontsova
Abstract Bis - bifunctional cis -4,7-diarylsubstituted-4,7-dihydroxy-4,7-dihydro[2.2]paracyclophanes 3,6 were synthesized by a highly diastereoselective reaction of ortho -substituted aryllithium reagents with [2.2]paracyclophane-4,7-quinone (1). Enantiomerically pure diols 3,5 were tested as chiral inductors in the enantioselective addition of diethylzinc to benzaldehyde (up to 93.5% ee). Acid dehydration of cis -4,7-di(2-methoxyphenyl)-4,7-dihydroxy-4,7-dihydro[2.2]paracyclophane (3) results in 4,7-dihydro-7,8-di(2-methoxyphenyl)[2.2]paracyclophane-4-one (8) , a planar chiral cyclohexadienone of the [2.2]paracyclophane series with a para -semiquinoid substructure. X-Ray investigations of compounds 3, 4 and 8 were performed. [source]

Enantioselective Preparation of 2-Aminomethyl Carboxylic Acid Derivatives: Solving the ,2 -Amino Acid Problem with the Chiral Auxiliary 4-Isopropyl-5,5-diphenyloxazolidin-2-one (DIOZ).

HELVETICA CHIMICA ACTA, Issue 6 2003
Preliminary Communication
Multigram amounts of suitably protected ,2 -amino acids with 17 of the 20 proteinogenic side chains are prepared by diastereoselective reactions of Li, B, or Ti enolates of the corresponding 3-acyl-4-isopropyl-5,5-diphenyloxazolidin-2-ones (acyl-DIOZ; 1) with appropriate electrophiles (amidomethylation, hydroxyalkylation, (benzyloxycarbonyl)methylation) in yields of 55,90% and with diastereoselectivities of 80 to >97% (Scheme). The primary products 2,8 thus obtained are converted to protected ,2 -amino acids by standard procedures (Table,1). Many of the DIOZ derivatives are highly crystalline compounds (31 X-ray crystal structures in Table,2). The chiral auxiliary DIOZ, readily prepared in either enantiomeric form, is recovered with high yield. [source]