This invention aims at providing a catalyst for producing an optically active aldehyde or an optically active ketone, which is an optically active carbonyl compound, by carrying out selective asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, particularly a catalyst which is insoluble in a reaction mixture for obtaining optically active citronellal which is useful as a flavor or fragrance, by carrying out selective asymmetric hydrogenation of citral, geranial or neral; and a method for producing a corresponding optically active carbonyl compound. The invention relates to a catalyst for asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, which comprises a powder of at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table, or a metal-supported substance in which at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table is supported on a support, an optically active cyclic nitrogen-containing compound and an acid.
Organocatalytic Asymmetric Formal [3+3] Cycloaddition Reactions of α,β-Unsaturated Aldehydes with Nazarov Reagents
作者:Ming-Kui Zhu、Qiang Wei、Liu-Zhu Gong
DOI:10.1002/adsc.200800174
日期:2008.6.9
An organocatalyticasymmetricformal [3+3] cycloaddition reaction of α,β-unsaturated aldehydes with Nazarov reagents promoted by prolinol derivatives afforded, after oxidation, 3,4-dihydropyranones in good yields with high enantioselectivities of up to 97% ee.
2.1 Die bekannten Verfahren zur Herstellung homochiraler Aminoalkohole der Formel I
worin R¹, R², R³ und * die in der Beschreibung angegebene Bedeutung aufweisen, durch Umsetzung der entsprechenden Säure mit metallorganischen Verbindungen sind entweder aufwendig, ergeben eine geringe Ausbeute oder auch nur geringe Enantiomerenreinheit. Das neue Verfahren soll diese Nachteile vermeiden.
2.2 Erfindungsgemäß werden N-silylierte Aminosäuresilylester der Formel II
worin R¹, R², R⁴ und * die in der Beschreibung angegebene Bedeutung haben, mit metallorganischen Verbindungen, insbesondere Grignard-Reagenzien in hoher Ausbeute und Enantiomerenreinheit umgesetzt.
2.3 Chirale Katalysatoren in der enantioselektiven Reduktion unsymmetrischer Ketone.
A practical enantioselective synthesis of .alpha.,.alpha.-diaryl-2-pyrrolidinemethanol. Preparation and chemistry of the corresponding oxazaborolidines
作者:David J. Mathre、Todd K. Jones、Lyndon C. Xavier、Thomas J. Blacklock、Robert A. Reamer、Julie J. Mohan、E. Tracy Turner Jones、Karst Hoogsteen、Mary W. Baum、E. J. J. Grabowski
DOI:10.1021/jo00002a049
日期:1991.1
A practical two-step enantioselective synthesis of alpha,alpha-diaryl-2-pyrrolidinemethanols (1) from proline, based on the addition of aryl Grignard reagents to proline-N-carboxanhydride (3), is reported. An investigation into the chemistry of the corresponding B-alkyl- and B-aryloxazaborolidines (2) led to the development of a reliable procedure for their preparation.
Chiral Pyridoxal-Catalyzed Asymmetric Biomimetic Transamination of α-Keto Acids
A series of chiral pyridoxals 8 and 9 have been developed from commercially available pyridoxine and (S)-alpha,alpha-diarylprolinols. The pyridoxals exhibited good catalytic activity in an asymmetric transamination of alpha-keto acids with 2,2-diphenylglycine (7f) as the amine source to give various alpha-amino acids in 29-85% yields with 53-80% ee's. The current asymmetric transamination has successfully mimicked a complete biological transamination process characterized by two half-transaminations, a small chiral pyridoxal molecule acting as the catalyst, and enantioselective control.