Pd(II)-catalyzed cascade Wacker-Heck reaction: chemoselective coupling of two electron-deficient reactants.
A novel palladium(II)-catalyzed oxy-carbopalladation process was developed allowing for the orchestrated union of hydroxy ynones with ethyl acrylate, two electron-deficient reactants. With beta-hydroxy ynones, this cascade Wacker-Heck process gave access to highly functionalized tri- or tetrasubstituted dihydropyranones featuring an unusual dienic system. For diastereomerically pure and for enantioenriched beta-hydroxyynones, these reactions proceed without affecting the stereochemical integrity of the existing stereocenters. In addition, tetrasubstituted furanones can be prepared when alpha-hydroxyynones and ethyl acrylate are used as starting materials. The dihydropyranones and furanones obtained upon cyclization are novel compounds, but structurally related carbohydrate derivatives featuring a similar dienic system have been used as starting materials for the construction of polyannulated products, suggesting that these cascade Pd(II)-mediated oxidative heterocyclizations are of value for various synthetic applications.
Silva
Franck
F
Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK.
Reiter
Maud
M
Mills-Webb
Rebecca
R
Sawicki
Marcin
M
Klär
Daniel
D
Bensel
Nicolas
N
Wagner
Alain
A
Gouverneur
Véronique
V