Silver-Promoted Direct Phosphorylation of Bulky C(sp<sup>2</sup>)–H Bond to Build Fully Substituted β-Phosphonodehydroamino Acids
作者:Hao-Qiang Cao、Hao-Nan Liu、Zhe-Yuan Liu、Baokun Qiao、Fa-Guang Zhang、Jun-An Ma
DOI:10.1021/acs.orglett.0c02229
日期:2020.8.21
A general and practical cross-dehydrogenative coupling protocol between readily available trisubstituted α,β-dehydro α-amino carboxylic esters and H-phosphites is described. This C(sp2)–H phosphorylation reaction proceeds with absolute Z-selectivity promoted by silver salt in a radical relay manner. The bulky tetrasubstituted β-phosphonodehydroamino acids were obtained in grams and added new modules
Ni(<scp>ii</scp>)-Catalyzed vinylic C–H functionalization of 2-acetamido-3-arylacrylates to access isotetronic acids
作者:Biswajit Roy、Eshani Das、Avijit Roy、Dipakranjan Mal
DOI:10.1039/d0ob00557f
日期:——
reaction for the synthesis of 4-aryl-substituted isotetronic acids from 2-acetamido-3-arylacrylates via vinylic C-H functionalization is reported. The reaction proceeds through heteroatom guided electrophilic insertion of nickel to the vinylic double bond followed by annulation with dibromomethane. This unconventional route features cascade steps, sole product formation, multiple functional group tolerance
Practical Enantioselective Hydrogenation of α-Aryl- and α-Carboxyamidoethylenes by Rhodium(I)-{1,2-Bis[(<i>o</i>-<i>tert</i>-butoxyphenyl)(phenyl)phosphino]ethane}
作者:Barbara Mohar、Michel Stephan
DOI:10.1002/adsc.201200780
日期:——
The rhodium(I)-1,2-bis[(o-tert-butoxyphenyl)(phenyl)phosphino]ethane} [Rh(I)-(t-Bu-SMS-Phos)] catalyst system displayed prime efficiency in the hydrogenation of large series of α-amidostyrenes and α-amidoacrylates. Up to >99.9% enantiomeric excesses coupled with very high reaction rates were attained operating routinely under 1–10 bar of hydrogen at 22 °C in methanol. Examples include industrial substrates
cyclization of N-acetyl enamines and intermolecular cyclocondensation of enamines and nitriles was investigated. The reaction was performed under mild conditions and gave oxazoles and imidazoles, respectively, in moderate to excellent yields. This transformation exhibits good reactivity, selectivity and functional group tolerance. The selectivity of the intra- or intermolecular reaction is dependent on the
Highly Enantioselective Hydrogenation of α-Dehydroamino Esters and Itaconates with Triphosphorous Bidentate Ligands and the Unprecedented Solvent Effect Thereof
作者:Weicheng Zhang、Xumu Zhang
DOI:10.1021/jo0622429
日期:2007.2.1
coordination in a Pd(II) complex of a phosphine-phosphoramidite ligand 1, which showed excellent enantioselectivity (up to 99.4% ee) in Rh-catalyzed hydrogenation of α-dehydroamino esters in acetone. A dramatic solvent effect was found in the hydrogenation of itaconates, which induces opposite chiralities of the product with the same catalytic system by the use of different solvents (e.g., 99.6% ee (R) in TFE