Calixarene-derived mono-iminophosphoranes: Highly efficient ligands for palladium- and nickel-catalysed cross-coupling
The first mono-iminophosphoranes based on a calix[4]arene skeleton have been synthesised and tested in the arylation of aryl bromides and aryl chlorides. Combining these ligands with [Pd(OAc)2] or [Ni(cod) 2] resulted in highly active Suzuki-Miyaura and Kumada-Tamao-Corriu cross-coupling catalysts, respectively. TOFs up to ca. 4×105 mol(ArBr)×mol(M)-1×h-1 were obtained in each case. The remarkable activities observed probably arise from the ligands' ability to form complexes with cavity-entrapped "MArX" moieties (endo-complexes), their highly crowded metal environment favouring formation of mono-ligated intermediates over that of less reactive bis-ligated ones. Possible supramolecular interactions within the cavity involving the receptor wall and the aromatic substrate may also significantly influence the reaction rates, notably by increasing the proportion of endo-complexes. Copyright
Staudinger reaction using 2,6-dichlorophenyl azide derivatives for robust aza-ylide formation applicable to bioconjugation in living cells
Efficient formation of water- and air-stable aza-ylides has been achieved using the Staudinger reaction between electron-deficient aromatic azides such as 2,6-dichlorophenyl azide and triarylphosphines. The reaction proceeds rapidly and has been successfully applied to chemical modification of proteins in living cells.
Meguro, Tomohiro,Terashima, Norikazu,Ito, Harumi,Koike, Yuka,Kii, Isao,Yoshida, Suguru,Hosoya, Takamitsu
supporting information
p. 7904 - 7907
(2018/07/25)
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