The first catalytic inverse-electron demand hetero-Diels–Alder reaction of nitroso alkenes using pyrrolidine as an organocatalyst
作者:Tobias C. Wabnitz、Steen Saaby、Karl Anker Jørgensen
DOI:10.1039/b316518c
日期:——
The first catalytic inverse-electron demand hetero-Diels-Alderreaction of nitroso alkenes has been developed. Nitroso alkenes were generated in situ from alpha-halooximes and underwent [4 + 2]-cycloadditions with enamines as dienophiles formed from aldehydes and pyrrolidine (10 mol%) as an organocatalyst. The presence of a suitable heterogeneous buffer system was found to be essential and best results
Preparation of 3-(Fluoroalkyl)-2-azadienes and Its Application in the Synthesis of (Fluoroalkyl)isoquinoline and -pyridine Derivatives
作者:Francisco Palacios、Concepción Alonso、Marta Rodríguez、Eduardo Martínez de Marigorta、Gloria Rubiales
DOI:10.1002/ejoc.200400770
日期:2005.5
A method for the preparation of 3-(fluoroalkyl)-substituted 2-azabutadienes 5 by aza-Wittig reaction of N-vinylic 3-(fluoroalkyl)phosphazenes 4 and aldehydes is reported. Thermal 6π-electrocyclization of these azadienes gives 3-(fluoroalkyl)-substituted isoquinolines 6. Also [4+2] cycloaddition of these heterodienes 5 with enamine 8 gives fluoroalkyl-substituted pyridine derivatives 10–16. However,
Aza-Wittig reaction of fluoroalkylated N-vinylic phosphazenes with carbonyl compounds. Usefulness of 2-azadienes for the preparation of fluoroalkyl pyridine derivatives
A method for the preparation of 3-fluoroalkyl substituted 2-aza-butadienes 6 by aza-Wittig reaction of 3-fluoroalkyl-N-vinylic phosphazenes 4 and aldehydes 5 is reported. [4+2] Cycloaddition reaction of these heterodienes 6 with enamines 9 gives fluoroalkyl substituted pyridine 15, 16, 24–27 and isoquinoline 12–14, 20 derivatives.
A new strategy to construct allylamines through reductive alkenylation of secondary amides with enamines is reported. The method features the use of trifluoromethanesulfonic anhydride as an activation reagent of amides, and enamines as unconventional alkenylation reagents. In this manner, enamines serve as surrogates of alkene carbanions instead of the classical enolates equivalents. A possible mechanism
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.