A Ag/P-stereogenic phosphine-complex-catalyzed 1,3-dipolarcycloaddition of azomethine ylides with electron-deficientolefins is reported. In this reaction, highly functionalized pyrrolines with a spiro-quaternary stereogenic center were obtained in good yields (up to 99%) with excellent levels of diastereo- (up to >20:1 dr) and enantioselectivities (up to >99% ee). The chirality of adducts was controlled
enantioselective strategy for the synthesis of optically pure nitro‐substituted pyrrolidines. In addition, the experimental results with regard to the carbon stereogenic center as well as the amide stereochemistry confirmed the potential of hemilabile atropisomers as chiral ligand in catalyticasymmetric [3+2] cycloaddition reaction.
Binap-Gold(I) versus Binap-Silver Trifluoroacetate Complexes as Catalysts in 1,3-Dipolar Cycloadditions of Azomethine Ylides
作者:María Martín-Rodríguez、Carmen Nájera、José M. Sansano、Abel de Cózar、Fernando P. Cossío
DOI:10.1002/chem.201101606
日期:2011.12.9
The 1,3‐dipolarcycloaddition between azomethine ylides and alkenes is efficiently catalysed by [(Sa)‐Binap‐Au(tfa)}2] (Binap=2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl; tfa=trifluoroacetyl). Maleimides, 1,2‐bis(phenylsulfonyl)ethylene, chalcone and nitrostyrene were suitable dipolarophiles even when using sterically hindered 1,3‐dipole precursors. The results obtained in these transformations improve
Asymmetric [3+2] Cycloaddition of Azomethine Ylides Catalyzed by Silver(I) Triflate with a Chiral Bipyrrolidine-Derived Phosphine Ligand
作者:Zhen-Jiang Xu、Chi-Ming Che、Xin Gu、Vanessa Lo
DOI:10.1055/s-0032-1316779
日期:——
bipyrrolidine-derived phosphine ligands L1 and L2 were synthesized. The ‘AgOTf + L1’ protocol catalyzes the asymmetric [3+2] cycloaddition of azomethineylides with alkenes to give highly substituted pyrrolidines in good yields (up to 90%) with moderate to high diastereoselectivities (up to >19:1 dr) and enantioselectivities (up to 76%). Two novel chiral bipyrrolidine-derived phosphine ligands L1 and L2 were synthesized
Silver-Catalyzed [3+3] Annulation of Glycine Imino Esters with Seyferth–Gilbert Reagent To Access Tetrahydro-1,2,4-triazinecarboxylate Esters
作者:Chi Wai Cheung、Jun-An Ma、Yin-Jun Huang、Jing Nie
DOI:10.1055/s-0039-1690894
日期:2020.7
A silver-catalyzed protocol for [3+3] annulation of glycine imino esters with Seyferth–Gilbert reagent was developed. A variety of phosphorylated tetrahydro-1,2,4-triazinecarboxylate esters were synthesized in moderate to good yields and with excellent diastereoselectivities. The dehydrogenation of a tetrahydro-1,2,4-triazine product to the corresponding triazine counterpart was also demonstrated.