A reversal of the standard regiochemistry of the Skraup−Doebner−Von Miller quinoline synthesis was observed when anilines were condensed with γ-aryl-β,γ-unsaturatedα-ketoesters in refluxing TFA. The reaction is proposed to involve 1,2-addition of the anilines to γ-aryl-β,γ-unsaturatedα-ketoesters to form Schiff's base adducts, followed by cyclization and oxidation. The products were unambiguously
Stereoselective Synthesis of Highly Functionalized Nitrocyclopropanes through the Organocatalyic Michael‐Addition‐Initiated Cyclization of Bromonitromethane and β,γ‐Unsaturated α‐Ketoesters
A highly diastereo‐ and enantioselective cyclopropanation of β,γ‐unsaturated α‐ketoesters with bromonitromethane has been successfully developed through a domino Michael‐addition/intramolecular‐alkylation strategy. Acceptable yields (up to 89 %) and enantioselectivities (up to 96 % ee) have been obtained.
Oxabenzomorphane: Synthese von 4-Phenyl-tetrahydropyran-2-carbonsäuren
作者:Fritz Eiden、Walter Winkler
DOI:10.1002/ardp.19863190806
日期:——
Durch [4+2]‐Cycloaddition der Enamine 6a–6f mit den Benzylidenbrenztraubensäureestern 7a–7g entstehen die 6‐Amino‐4‐phenyl‐dihydropyran‐2‐carbonsäureester 8a–8p. Aus 8d wird durch Hydrolyse, Wasserabspaltung und katalytische Hydrierung die 4‐Phenyl‐tetrahydropyran‐2‐carbonsäure 12a gewonnen.
Reactions of pyruvates: organocatalytic synthesis of functionalized dihydropyrans in one pot and further transformations to functionalized carbocycles and heterocycles
作者:Pandurang V. Chouthaiwale、Fujie Tanaka
DOI:10.1039/c4cc06035k
日期:——
Concise cascade reactions of pyruvates with aldehydes that generate functionalized dihydropyran derivatives in one pot have been developed. The products, dihydropyrans, were further concisely transformed to various functionalized molecules.
High enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters catalyzed by bifunctional thioureas
作者:Swapna Konda、John C.-G. Zhao
DOI:10.1016/j.tetlet.2014.07.112
日期:2014.9
A highly enantioselective Michael addition of malonates to β,γ-unsaturatedα-ketoesters was achieved using cinchona alkaloid-derived thioureas as the bifunctional catalyst. The corresponding Michael addition products were obtained in excellent yields (90–99%) and ee values (up to >99% ee) using a quinidine-derived thiourea as the catalyst under neat conditions. The opposite enantiomer may be obtained