Cyclopropanes Diphosphine

Larsen, J., Rasmussen, B.S., Hazell, R.G. and Skrydstrup, T, (2004) Preparation of a novel diphosphine-palladium macrocyclic complex possessing a molecular recognition site. Oxidative addition studies. Chem, Commun., 202-203 Braunstein, P., Clerc, G. and Morise, X. (2003) Cyclopropanation and Diels-Alder reactions catalyzed by the first heterobimetallic complexes with bridging phosphinooxazoline ligands. New J. Chem., 27,68-72 Braunstein, P., Clerc, G., Morise, X., Welter, R. and Mantovani, G. (2003) Phosphinooxazolines as assembling ligands in heterometallic complexes. Dalton Trans., 1601-1605. 

The rhodium-catalyzed successive C-C/C-O bond cleavage reaction of a cyclobutanone 77 containing a phenoxymethyl side chain was affected by the employed bidentate diphosphine ligand (Scheme 3.44) [53]. In the presence of [Rh(nbd)(dppe)]PF 5 (nbd, norborna-2,5-diene dppe, l,2-bis(diphenylphos-phino)ethane) (5 mol%) and diphenylacetylene (20 mol%), cyclobutanone 77 was transformed into the alkenoic ester 78 in 88% yield via C-C bond cleavage, P-oxygen elimination, and reductive elimination. In contrast, the [Rh(nbd)(dppp)]PFg-catalyzed (dppp, l,3-bis(diphenylphosphino)propane) reaction afforded cyclopentanone 79 in 81% yield through a rhodacyclohexanone species that was formed by 6-endo cyclization. The reaction of the cyclobutanone 77 catalyzed by [Rh(nbd)(dppb)]PFg (dppb, l,4-bis(diphenylphosphino)butane) led to exclusive formation of cyclopropane 80 via decarbonylation. 

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