Phosphine-catalyzed ring-opening

This reaction has been modified for various conditions, such as the application of microwave irradiation and the application of phosphine-containing polymer prepared from the ruthenium-catalyzed ring-opening metathesis polymerization of the norbornene. Most importantly, this reaction has been extended to the coupling of primary or secondary alkyl halides with aryl, vinyl, and even alkyl halide (or tosylate) 31,3o,3p,3y,3dd,3nn,4v,4x,6... 

Rhodium-catalyzed ring-opening isomerization and hydrogenation of [ (diphenylphosphino)oxy methyl]cyclopropane (1) formed linear products via cleavage of the C1-C2 bond by assistance of a chelating phosphine group (Scheme 2.2) [5]. 

Tokuoka, E. Kotani, S. Matsimaga, H. Ishizuka, T. Hashimoto, S. Nakajima, M. (2005) Asymmetric ring opening of meso-epoxides catalyzed by the chiral phosphine oxide BINAPO., Tetrahedron Asymmetry 16 2391-2392. 

Among the catalysts used are Lewis acids991 and phosphine-nickel complexes.992 Certain of the reverse cyclobutane ring openings can also be catalytically induced (8-40). The role of the catalyst is not certain and may be different in each case. One possibility is that the presence of the catalyst causes a forbidden reaction to become allowed, through coordination of the catalyst to the -it or a bonds of the substrate.993 In such a case the reaction would of course be a concerted 2S + 2S process. However, the available evidence is more consistent with nonconcerted mechanisms involving metal-carbon a-bonded intermediates, at least in most cases.994 For example, such an intermediate was isolated in the dimerization of nor-bornadiene, catalyzed by iridium complexes.995... 

The addition of nitriles to 3,3-dihexylcyclopropene 11 produces the corresponding allylated nitriles (Scheme 2, Eq. 5) [10]. The diallylation product 12b is isolated in the reaction with the active methylene lb (Eq. 12). The non-ring-opened products 15 are produced in the Pd-catalyzed hydrocarbonation of methyleneaziridines 14 (Scheme 2, Eq. 6) [11]. Although this reaction can proceed in the presence of Pd catalyst only, the use of phosphine monodentate ligands provides better results. 

An X ray examination of the product from the interaction of (2B,4fi,5S)-(-)-3,4-dimethyl-2-phenyl-1,3,2-oxazaphospholidine 2-oxide with an aryl Grignard reagent has demonstrated that ring opening occurs with retention of configuration at phosphorus in accord with Inch s work, but at variance with that of Koizumi, and also in stereochemical opposition to that displayed by acyclic analogues (Mislow). Acid catalyzed alcoholysis of the acyclic phosphinic amide... 

The stannylated product 272 can be induced to undergo ring-opening by treatment with MeLi, either via a transmetallation or the ate complex. This overall sequence provides the reductive ring opened product 273 with complementary regioselectivity to that obtained through nickel and phosphine-catalyzed hydro-alumination. 

Asymmetric induction by the use of chiral phosphines was explored in the palladium-catalyzed phenylation of 257 [225]. The yields and enantioselectivi-ties of the ring opened products are highly variable. For example, 300 a was obtained in 96% ee with (k)-BINAP as ligand but the yield was very poor, Eq. 203. The addition of ZnCl2 increased the yield of the ring opened product to... 

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