syn-Selective Direct Asymmetric Cross-Aldol Reaction
نویسندگان
چکیده
منابع مشابه
Direct asymmetric aldol-Tishchenko reaction of aliphatic ketones catalyzed by syn-aminoalcohol-Yb(III) complexes.
The asymmetric direct aldol condensation of aldehydes with ethyl- and propylketones is catalyzed by syn-alpha-aminoalcohol-Yb(OTf)3 complexes, yielding the anti-1,3-diol monoesters with high diastereocontrol and good enantioselectivity. Three adjacent stereogenic centers are created in a simultaneous aldol condensation and Evans-Tishchenko reduction in an acyclic system.
متن کاملUnexpected syn hydride migration in the non-aldol aldol reaction.
[structure: see text] Non-aldol aldol rearrangement of the epoxy silyl ether 13b afforded the expected anti methyl ketone 14, while the diastereomeric epoxy silyl ether 13a afforded the syn methyl ketone 8b via an unprecedented syn hydride migration. Calculations suggest that this unusual reaction proceeds via the carbocation, which cannot easily rotate due to steric hindrance.
متن کاملThe small peptide-catalyzed direct asymmetric aldol reaction in water.
Simple modular di- and tripeptides with a primary amine at the N-terminus catalyze the aqueous asymmetric aldol reaction between unmodified ketones and aldehydes to furnish the corresponding beta-hydroxy ketones with up to 86% ee in water and 99% ee in aqueous media.
متن کاملsyn-Selective asymmetric cross-aldol reactions between aldehydes and glyoxylic acid derivatives catalyzed by an axially chiral amino sulfonamide.
syn-Selective asymmetric cross-aldol reactions of aldehydes with tert-butyl glyoxylate and glyoxamide were realized by the use of an axially chiral amino sulfonamide (S)-1. The cross-aldol products obtained are densely functionalized and readily converted to synthetically useful and important chiral building blocks such as γ-lactone and γ-lactam.
متن کاملWater-compatible organocatalysts for direct asymmetric syn-aldol reactions of dihydroxyacetone and aldehydes.
A novel organocatalyst was developed that effectively catalyzed the reactions of unprotected or protected dihydroxyacetone with a variety of aldehydes to provide syn-aldol products with good yields and ee values up to >99%. Significantly, this amide catalyst was effective with a variety of nonaromatic aldehyde acceptors that had proven difficult in the presence of other catalysts. Reactions of ...
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ژورنال
عنوان ژورنال: Synfacts
سال: 2007
ISSN: 1861-1958,1861-194X
DOI: 10.1055/s-2007-968351