A New Catalytic Activity of Antimony(III) Chloride in Palladium(0)-Catalyzed Conjugate Addition of Aromatics to .alpha.,.beta.-Unsaturated Ketones and Aldehydes with Sodium Tetraphenylborate and Arylboronic Acids
摘要:
A remarkable catalytic effect of antimony(III) chloride is disclosed in palladium(0)-catalyzed conjugate addition of aromatics to alpha,beta-unsaturated ketones and aldehydes with sodium tetraphenylborate and arylboronic acids in acetic acid at 25 degrees C. Several other metal chlorides such as AlCl3, SnCl4, AsCl3, TiCl4, FeCl3, MoCl5, and CeCl3 are also effective in some cases, but SbCl3 is the salt of choice. Two key steps are proposed for this reaction: one is the oxidative addition of a C-B bond to Pd(0) forming an arylpalladium species, and the other is the formation of an antimony enolate derived from the initial coordination of SbCl3 to the carbonyl oxygen of an organopalladium intermediate.
Substitution of allylic alcohols to form a carboncarbonbond is accomplished by a simple reaction of the allylic alcohol itself with an enoxysilane, catalyzed by [Ir(cod)(PPh3)2]X which is activated by H2 molecule. The anion part X of the complexes plays an important role to enhance the rate and product yields of the reactions. The efficacy of the catalyst increases with switching X in the order of