Organocatalytic Asymmetric Reaction Cascade to Substituted Cyclohexylamines
作者:Jian Zhou、Benjamin List
DOI:10.1021/ja072134j
日期:2007.6.1
We report a new strategy for organocatalytic cascade reactions. Accordingly, enamine catalysis, iminium catalysis, and Bronsted acid catalysis can work in concert in a highlyenantioselective organocatalytic cascadesequence toward chiral cis-3-substituted cyclohexylamines. We found that an achiral amine in combination with a catalytic amount of a chiral Bronsted acid can accomplish an aldol additi
Regio- and Stereoselective Monoamination of Diketones without Protecting Groups
作者:Robert C. Simon、Barbara Grischek、Ferdinand Zepeck、Andreas Steinreiber、Ferdinand Belaj、Wolfgang Kroutil
DOI:10.1002/anie.201202375
日期:2012.7.2
Hitting the right target: Differentiation between two keto moieties was accomplished by a regio‐ and enantioselective bioamination employing ω‐transaminases. Using 1,5‐diketones as substrates gave access to the opticallypure 2,6‐disubstituted piperidine scaffold. The approach allowed the shortest synthesis of the alkaloid dihydropinidine, as well as its enantiomer, by choosing an appropriate ω‐transaminase
Synthesis of <i>trans</i>-3-Substituted Cyclohexylamines via Brønsted Acid Catalyzed and Substrate-Mediated Triple Organocatalytic Cascade Reaction
作者:Benjamin List、Jian Zhou
DOI:10.1055/s-2007-984877
日期:——
We report a new organocatalytic cascade reaction. A combination of the amine substrate with a catalytic amount of a Brønsted acid merges enamine and iminium catalysis with Brønsted acid catalysis in a new organocatalytic cascade reaction. We found that the aniline substrate itself in combination with a catalytic amount of PTSA·H2O can function as an aminocatalyst accomplishing an aldol condensation-conjugate reduction cascade, which terminates in a Brønsted acid catalyzed reductive amination incorporating the amine substrate into the final product. This transformation furnishes trans-3-substituted cyclohexyl amines in good yields and good diastereoselectivities.
Chemoenzymatic Synthesis of All Four Diastereomers of 2,6-Disubstituted Piperidines through Stereoselective Monoamination of 1,5-Diketones
作者:Robert C. Simon、Ferdinand Zepeck、Wolfgang Kroutil
DOI:10.1002/chem.201202793
日期:2013.2.18
evaluated for the stereoselective monoamination of designated 1,5‐diketones; excellent conversions, enantio‐ and regioselectivities were observed. The resulting amino‐ketones underwent spontaneous intramolecular ringclosure to afford Δ1‐piperideines, which served as precursors for the cis‐ and anti‐piperidine scaffold as demonstrated for the synthesis of the alkaloids dihydropinidine and epi‐dihydropinidine