Stille coupling involving bulky groups feasible with gold cocatalyst
Gold shuttle: Bulky groups, which will not (or only very sluggishly) undergo Stille coupling with stannanes and inexpensive ligands, can be efficiently coupled using bimetallic catalysis. A gold cocatalyst serves as an efficient shuttle to convey the bulky group from tin to palladium by reducing the steric crowding in the transition-states (see scheme). Copyright
Delpozo, Juan,Carrasco, Desiree,Perez-Temprano, Monica H.,Garcia-Melchor, Max,Alvarez, Rosana,Casares, Juan A.,Espinet, Pablo
Mild and Efficient Synthesis of Diverse Organo-AuI-L Complexes in Green Solvents
An exceptionally mild and efficient method was developed for the preparation of (hetero)aryl-AuI-L complexes using ethanol or water as the reaction medium at room temperature and Ar-B(triol)K boronates as the transmetalation partner. The reaction does not need an exogeneous base or other additives, and quantitative yields can be achieved through a simple filtration as the only required purification method, which obviates considerable waste associated with alternative workup methods. A broad reaction scope was demonstrated with respect to both the L and (hetero)aryl ligands on product Au complexes. Despite the polar reaction medium, large polycyclic aromatic hydrocarbon units can be incorporated on the Au complexes in very good to excellent yields. The approach was demonstrated for the chemoselective manipulation of orthogonally protected aryl boronates to afford a new class of N-heterocyclic carbene-Au-aryl complexes. A mechanistic rationale was proposed.
Ingner, Fredric J. L.,Schmitt, Ann-Cathrin,Orthaber, Andreas,Gates, Paul J.,Pilarski, Lukasz T.
p. 2032 - 2037
(2020/03/11)
Palladium-catalyzed cross-coupling reactions of organogold(i) phosphanes with allylic electrophiles
Aryl and alkenylgold(i) phosphanes react regioselectively with allylic electrophiles such as cinnamyl and geranyl halides (bromide, chloride and acetates) under palladium catalysis in THF at 80 °C to afford the α-substitution product with moderate to high yields. When the reaction is performed with a chiral enantiopure secondary acetate, the α-substituted cross-coupling product is obtained with complete inversion of the stereochemistry.
Pena-Lopez, Miguel,Ayan-Varela, Miguel,Sarandeses, Luis A.,Sestelo, Jose Perez
p. 1686 - 1694
(2012/03/22)
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