Highly enantioselective ene-type spiro-cyclization of allyl propargyl ethers catalyzed by cationic palladium(II) complexes with a new type of PN-ligand bearing achiral gem-dimethyl oxazoline

Highly enantioselective spiro cyclization of 1,6-enynes catalyzed by cationic skewphos rhodium(i) complex

A cationic rhodium(I) complex having a skewphos ligand is shown to be a highly enantioselective catalyst for asymmetric carbocyclization of 1,6-enynes with tri-substituted olefins to control quaternary stereogenic centers of spiro-rings.

A highly efficient asymmetric Suzuki–Miyaura coupling reaction catalyzed by cationic chiral palladium(ii) complexes

Cationic chiral palladium(ii) complexes are shown to catalyze the asymmetric coupling reaction of aryl boronates and aryl halides within a short period of time in good yield and enantioselectivity.

Rhodium Complex-Catalyzed Cycloisomerization of Allenenes: Exo and Endo Cyclization Depending on the Auxiliary Ligands

In the presence of a catalytic amount of a rhodium(I) complex, allenenes undergo cycloisomerization reactions resulting in the selective formation of exo-alkylidenecarbocycles and heterocycles. In the catalytic system of rhodium complexes with triaryl phosphites, cyclic 1,4- or 1,5-dienes are formed in good to excellent yields in the formal exo-cyclization mode via the metallacycle intermediate having an exo-alkylidene moiety. In this cycloisomerization, (E)- and (Z)-allenenes are transformed stereospecifically to the corresponding cyclic (E)- and (Z)-1,4-dienes, respectively. On the other hand, the reactions under carbon monoxide atmosphere exclusively afford seven-membered-ring products through an endo-mode cyclization. The unusual cyclization involves an allylic C-H activation process. The allenene bearing a silicon substituent at the olefinic terminus incorporates carbon monoxide to give the corresponding [2+2+1] cycloaddition product. This result apparently indicates that the catalysis of the rhodium complex is explained in terms of the oxidative cyclization of an allenene to furnish the key exo-alkylidene metallacycle intermediate at the first stage of the catalysis.