Enantioselective synthesis of planar chiral ferrocenes via palladium-catalyzed annulation with diarylethynes

• Yan-Chao Shi,
• Rong-Fei Yang,
• De-Wei Gao and
• Shu-Li You

Beilstein J. Org. Chem. 2013, 9, 1891–1896, doi:10.3762/bjoc.9.222

• ). The allylic substitution reactions of (rac)-4 had been carried out. The allylic alkylation reaction proceeded in 95% yield and 44% ee (Scheme 3, reaction 1) and the allylic amination reaction proceeded in 32% yield and 43% ee (Scheme 3, reaction 2) [69][70][71]. Although only moderate

• could be transformed readily into a P,N-ligand, which was found to be suitable for Pd-catalyzed allylic substitution reactions. Experimental General procedure for the enantioselective synthesis of planar chiral ferrocenes To a solution of alkyne 2 (0.46 mmol) in DMA (1.5 mL) was added Boc-L-Val-OH (8.7

Chiral multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita–Baylis–Hillman carbonates with maleimides

• Hong-Ping Deng,
• De Wang,
• Yin Wei and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 1098–1104, doi:10.3762/bjoc.8.121

• was shown that chiral multifunctional thiourea-phosphines were excellent catalysts for the asymmetric aza-MBH reaction, asymmetric allylic substitution of MBH adducts, and asymmetric [3 + 2] annulation of MBH carbonates with electron-deficient olefins [52][53][54][55][56]. Hence, we initially used

A practical two-step procedure for the preparation of enantiopure pyridines: Multicomponent reactions of alkoxyallenes, nitriles and carboxylic acids followed by a cyclocondensation reaction

• Christian Eidamshaus,
• Roopender Kumar,
• Mrinal K. Bera and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2011, 7, 962–975, doi:10.3762/bjoc.7.108

• and enones, as well as in palladium-catalyzed allylic substitution reactions [14][15][16][17][18][19][20]. Thus, the synthesis of specifically functionalized pyridines is of considerable interest, and many approaches toward this heterocyclic structure have been disclosed in the literature [21]. In

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

• Benan Kilbas and
• Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

• -withdrawing groups will enhance the stability of the complex [25][26]. The next step is the ionization step followed by allylic substitution. The final step is the decomplexation. Trost et al. [3] and Fiaud et al. [6] have proposed that only metal–olefin complexation anti to the leaving group will lead to the

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• transformations in the presence of ruthenium catalysts, which are able to perform regioselective allylic substitution by O-, N- and C-nucleophiles (Scheme 8a) [55] and elimination to provide a new access to dendralenes (Scheme 8b) [56]. Higher olefin–alkyne cross-metathesis This cross-metathesis reaction was

Understanding the mechanism of Pd-catalyzed allylic substitution of the cyclic difluorinated carbonates

• Jun Xu,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2008, 4, No. 18, doi:10.3762/bjoc.4.18

• , Shanghai 201620, China 10.3762/bjoc.4.18 Abstract We present a mechanistic investigation of Pd-catalyzed allylic substitution of cyclic gem-difluorinated carbonates 1 and 4, previously employed in the synthesis of 3',3'-difluoro-2'-hydroxymethyl-4',5'-unsaturated carbocyclic nucleosides in 17 steps. The

• allylic substitution, in which the regioselectivity was reversed from that of nonfluorinated substrates. This reversed regioselectivity caused by fluorine interests us greatly. Herein, we present a mechanistic investigation of Pd-catalyzed allylic substitution of cyclic gem-difluorinated carbonates

• our knowledge, the effect of gem-difluoromethylene group on Pd-catalyzed cyclic allylic substitution has never been addressed so far. The regioselectivity was totally different from those of nonfluorinated substrates [18]. Unexpected and specific regioselectivity of Pd-catalytic asymmetric reactions

A superior P-H phosphonite: Asymmetric allylic substitutions with fenchol- based palladium catalysts

• Bernd Goldfuss,
• Thomas Löschmann,
• Tina Kop-Weiershausen,
• Jörg Neudörfl and
• Frank Rominger

Beilstein J. Org. Chem. 2006, 2, No. 7, doi:10.1186/1860-5397-2-7

• -ligands (Table 1). Conclusion Besides P, N-bidentate FENOP ligands, monodentate BIFOP ligands can be employed successfully in Pd-catalyzed allylic substitution of 1-phenyl-2-propenyl acetate with dimethylmalonate. Surprisingly, the halogen phosphites BIFOP-Cl and BIFOP-Br are stable towards nucleophiles

• extrapolated energies: BIFOP-H-re: -1025.01553 H, BIFOP-H-si: -1025.01466 H. The by 0.5 kcal mol-1 slightly preferred re-addition of the NH3 model nucleophile corresponds to the experimental S-alkylation product. Pd-catalyzed allylic substitution with unsymmetrical substrates (Nu = dimethylmalonate, Nf = OAc