Enantioselective palladium catalyzed

Campos, K.R., Klapers, A., Waldman, J.H., Dormer, P.G., Chen, C.Y. (2006) Enantioselective, Palladium-Catalyzed a-Arylation of N-Boc-pyrrolidine. Journal of the American Chemical Society, 128, 3538-3539. 

A detailed study of the mechanism of the enantioselective palladium catalyzed hydrosilylation of styrene with trichlorosilane was carried out with combined QM/MM ab initio molecular dynamics simulations. A number of fundamental mechanistic questions have been addressed, including the main features of the catalytic cycle, as well as the specific nature of the regioselectivity and enatioselectivity. 

Deerenberg, S., Schrekker, H.S., van Strijdonck, G.P.F., Kamer, P.C.J., van Leeuwen, P.W.N.M., Fraanje, J, and Goubitz, K. (2000) New chiral phosphine-phosphite hgands in the enantioselective palladium-catalyzed allylic alkylation. 

T. Hayashi and M. Kumada, Asymmetric Coupling Reactions, in J. D. Morrison, ed., Asymmetric Synthesis, Vol. 5, Chap. 5, Academic Press, New York, 1985 J. C. Fiaud, Mechanisms in Stereo-Differentiating Metal-Catalyzed Reactions. Enantioselective Palladium-Catalyzed Allylation, in A. F. Noels, M. Graziani, and A. J. Hubert, eds., Metal Promoted Selectivity in Organic Synthesis, p. 107, Kluwer Academic, Dordrecht, 1991. 

Novel, chiral thiophene- (e.g. 122) and benzo[/>]thiophene-based phosphines have been prepared and evaluated as ligands in an enantioselective palladium-catalyzed allylation reaction <02SL2083>. 

He, X. C. Wang, B. Yu, G. L. Bai, D. L. Studies on the asymmetric synthesis of huperzine A. Part 2 highly enantioselective palladium-catalyzed bicycloannulation of the beta-keto-ester using new chiral ferrocenylphosphine ligands. Tetrahedron-Asymmetry, 2001, 12(23) 3213-3216. 

Allylic Substitution Use of 2-[(45)-4-( 1,1 -dimethylethyl)-4,5-dihydro-2-oxazolyl]-6-methylpyridine(l) for enantioselective palladium-catalyzed allylic substitution has been reported. 

Tietze LF, Ila H, Bell HP. Enantioselective palladium-catalyzed transformations. Chem. Rev. 2004 104 3453-3516. 

Larock, R. C., Zenner, J. M. Enantioselective, Palladium-Catalyzed Hetero- and Carboannulation of Allenes Using Functionally-Substituted Aryl and Vinylic Iodides. J. Org. Chem. 1995, 60, 482-483. 

Fiaud, J. C. Mechanisms in stereo-differentiating metal-catalyzed reactions. Enantioselective palladium-catalyzed allylation. Catal. Metal Compl. 1991, 12, 107-131. 

Helmchen, G. Enantioselective palladium-catalyzed allylic substitutions with asymmetric chiral ligands. J. Organomet. Chem. 1999, 576, 203-214. 

Enantioselective palladium-catalyzed transformations in syntheses and reactions of heterocycles 04CRV3453. 

The use of a chiral bisoxazoline ligand 109 for the enantioselective palladium-catalyzed annelation of allenes has been reported by Larock and Zenner (an example is given in Scheme 32) [82]. Even though the alkene insertion step here is followed by an intramolecular nucleophihc attack of the amine functionality... 

Ripa, L. and Hallberg, A. (1997) Intramolecular enantioselective palladium-catalyzed Heck arylation of cyclic enamides. J. Org. Chem., 62, 595-602. 

The same year, Hayashi and colleagues described an enantioselective palladium-catalyzed intramolecular carbonylative coupling of aryl and alkenyl triflates [29]. Enantiomerically enriched cyclopentenones were prepared in high yields... 

Gambs, C. Chaloupka, S. Consigho, G Togni, A. Ligand electronic effect in enantioselective palladium-catalyzed copolymerization of carbon monoxide and propene. Angew. Chem., Int. Ed. 2000, 39, 2486-2488. 

Mechanism in Stereo-Differentiating Metal-Catalyzed Reactions. Enantioselective Palladium-Catalyzed Allylation. 

Enantioselective Palladium-Catalyzed Allylic Substitutions with Asymmetric Chiral Ligands. 

Scheme 23 Enantioselective palladium-catalyzed ring expansion of /ert-cyclopropanols and tert-cyclobutanols...

Scheme 31 Enantioselective palladium-catalyzed [4-1-3] cycloaddition involving ACPs...

The total synthesis of L-showdomycin was realized efficiently in 10 synthetic steps by using this efficient enantioselective palladium-catalyzed allylic alkylation (eq 70). ... 

E. Enantioselective Palladium-catalyzed Carbocyclization of a Nitroacetate for the Eigoline Skeleton... 

Scheme 5.9 Diastereoselective and/or enantioselective palladium-catalyzed allylic alkylation of cyclohexanone through the magnesium or lithium enolate.

Scheme 5.11 Regioselective, diastereoselective, and enantioselective palladium-catalyzed allylic alkylation of acylsilanes through thar lithium enolates.

Scheme 5.12 Enantioselective palladium-catalyzed allylic alkylation of tertiary amides 32 through their lithium enolates.

Scheme 5.15 Diastereoselective and/or enantioselective palladium-catalyzed allylation of 5-valerolactone through the lithium enolate 46.

Scheme 5.43 Enantioselective palladium-catalyzed decarboxylative allylic alkylation under ring opening of bicyclic racemic ketone 130.

Buchwald and coworkers elaborated a protocol for the enantioselective palladium-catalyzed arylation of ketones 143 with various aryl bromides. 

Scheme 5.47 Enantioselective palladium-catalyzed enolate arylation of racemic aminomethylene ketones 143 mediated by chiral ligands 144.

Scheme 5.50 Enantioselective palladium-catalyzed arylation of enolates derived from racemic oxindoles 152, mediated by the axially chiral and P-stereogenic ligand 153.

Campos KR, Klapars A, Waldman JH, Dormer PG, Chen C-yi. Enantioselective, palladium-catalyzed a-arylation of Al-Boc-pyrrolidine. J. Am. Chem. Soc. 2006 128(11) 3538-3539. 

Recent studies revealed that (2S)-tocopherols have no antioxidant effect in biological systems because they are not accepted as substrates by the a-tocopherol transfer protein (TTP), which is responsible for the transport of vitamin E into the tissue. As a result, the enantioselective synthesis of the a-tocopherol became attractive, and several groups have reported on its asymmetric synthesis. In addition, Tietze and co-workers reported on an enantioselective palladium-catalyzed total synthesis of vitamin E by employing a domino Wacker-Heck reaction (Scheme 21.15). ° In their study, reaction of 64 with methyl acrylate in CH2CI2 with catalytic amounts of Pd(TFA)2 (TEA = trifluoroacetate), the chiral ligand (5,5)-Bn-BOXAX 65, and p-benzoquinone afforded the desired chroman 66 with 96% ee in 84% yield. The enantioselective cascade reaction described therein provided the efficient construction of the chroman firamework of vitamin E 67 with concomitant introduction of part of the side chain in high yields and high enantioselectivities. 

Tietze LF, Stecker F, Zinngrebe J, Sommer KM. Enantioselective palladium-catalyzed total synthesis of vitamin E by employing a domino Wacker-Heck reaction. Chem. Eur. J. 2006 12(34) 8770-8776. 

Interestingly, investigations have also been focused on the enantioselective palladium-catalyzed nucleophilic fluo-rination of Pd(II)-allyl species by a judicious choice of the allylic living group, the fluoride source and the ligand. A... 

---