Asymmetric cyclopalladation

The asymmetric cyclopalladation of dimethylaminomethylferrocene takes place in the presence of an optically active carboxylic acid (e.g, A -acetylvaline), giving the cyclopalladation product 478 in 78% ee, from which optically active ferrocene derivatives were prepared[434]. 

The asymmetric aza-Claisen rearrangement of allyl imidates, (86) (87), has been shown to be catalysed by homochiral cationic palladium(II) complexes, and a series of enantiopure cyclopalladated ferrocenyl amines and imines have been... 

Overman and co-workers carried out extensive studies on Pd(II)-catalyzed asymmetric allylic rearrangement of allylic imidates to form enantioenriched allylic amides. They achieved 97 % ee as the best result by the reaction of the allylic imidate 612 using the cyclopalladated ferrocenyl oxazoline 613 having elements of planar chirality as a catalyst precursor, and discussed the mechanism of the reaction [220]. 

An interesting application of the chiral cyclopalladated complexes is palladium-promoted asymmetric Diels-Alder reactions of l-phenyl-3,4-dimethylphosphole (Scheme 4). In the original report on the Diels-Alder reaction of the phosphole reported by Nelson and co-workers, the dichloropalladium species was employed as a promoter.f In 1994, Leung showed that a chiral cyclopalladated complex was capable of promoting the Diels-Alder reaction. In this reaction, the chiral palladacycle worked as a chiral auxihary and showed almost perfect diastereoselectivity. It has been revealed that simultaneous precoordination of a diene and a dienophile to the palladium center is essential for the reaction. Thus, both dienes and dienophiles should possess Lewis basic functionahty. The diene l-phenyl-3,4-dimethylphosphole has been the only substrate examined so far, while a variety of dienophiles, such as vinylphosphine, vinyl-sulfoxide, vinylsulfide, acrylamide, vinylarsine, vinylpyridine, vinyl-pyrrole, or methylenequinuchdinone, have successfully been applied to this asymmetric Diels-Alder reaction. 

Chen K, Pullarkat SA, Li Y, Leung PH (2012) Chiral cyclopalladated complex promoted asymmetric synthesis of diest -substituted P, N-ligands via stepwise hydrophosphination and hydroamination reactions. J Chem Soc Dalton Trans 41 5391-5400... 

CF3CSCCF2 to give selective asymmetric oxidative coupling of the cyclopalladated organo groups leading to the formation of the novel... 

An asymmetrically folded dinuclear phenylhydrazonato anionic complex containing two different hydrazonato ligands of palladium containing a Pd-G(aryl) bond cis to a Pd-N(amido) bond was described. Interesting dinuclear cyclopalladated 1,2- and 1,3-bridged squarato complexes containing cyclopalladated 2,6-dimethylazobenzene have appeared. 

Insertion of other unsaturated molecules such as GO or isonitriles in this type of palladacycle affords new types of <7,77 -enylpalladium complexes where the size of the cycle is increased in one carbon atom (Scheme 79). Cyclopalladated complexes derived from ferrocene also undergo double insertion of alkynes to give Equation (56) shows an example. It has been found for these systems that asymmetrically substituted internal alkynes insert in a head-to-tail manner. ... 

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