Chiral diimine-based catalysts

F. Aziridination of Alkenes with Chiral Diimine-based Catalysts. 119... 

ILL. Zhen and K. R. Conser, Asymmetric Alkene Aziridination and Readily Available Chiral Diimine-Based Catalysts, J. Am. Chem. Soc., 115(1993)5326. 

Li Z, Conser KR, Jacobsen EN. Asymmetric alkene aziridination with readily available chiral diimine-based catalysts. 7. Aw. Chem. Soc. 1993 115(12) 5326-5327. 

Discussion Point DPS The previously unexpected observation of side-chain branches in diimine-nickel catalyzed polyethylene formation is explained by the reaction scheme represented in Figure 15. Propose related chain migration schemes which explain i) the chain straightening , i.e. the incorporation of propylene methyl substituents into the backbone of polypropylene chains produced by these catalysts, ii) the 2,co-concatenation of higher a-olefins by some Ni-based catalysts, and Hi) the introduction of stereoerrors in isotactic polypropylene by chain-migration of chiral ansa-zirconocene catalysts. 

Platinum complexes show none of the catalytic activity found in palladium and nickel complexes. This chemical inertness makes platinum a useful model for the more active catalysts. There has been a suggestion that platinum complexes of chiral a-diimines might lead to stereoselective olefin polymerization. Chiral camphor-based ligands have been employed in palladium complexes for ethylene polymerization, but there was no mention of stereoselectivity in hexene polymerizations. 

Schmid, M., Eberhardt, R., Klinga, M et aL (2001) New C y- and chiral C2-symmetric olefin polymerization catalysts based on nickel(II) and palladium(II) diimine complexes bearing 2,6-diphenyl aniline, moieties Synthesis, structural characterization, and first insight into polymerization poperties. Organometallics, 20,2321 2330. 

---