A convenient synthetic route to polypyridine-esters by palladium-promoted carboalkoxylation
作者:Abdelkrim El-ghayoury、Raymond Ziessel
DOI:10.1016/s0040-4039(98)00820-x
日期:1998.6
smoothly with CO (1 atm) and n-butanol in the presence of a tertiary amine and a catalytic amount of bis(triphenylphosphine)palladiumdichloride to afford the corresponding esters. When ethanol and a disubstituted substrate are used under milder conditions, selective mono-carboalkoxylation occurs. Amidation is effected using a primaryamine as nucleophile.
Facile Synthesis of Polypyridine Esters: A Route to Functionalized Aldehydes
作者:Abdelkrim El-ghayoury、Raymond Ziessel
DOI:10.1021/jo000635g
日期:2000.11.1
synthesized and fully characterized. The principal reaction involves the palladium(0)-catalyzed carboalkoxylation of the bromo-, chloro- or triflate-substituted pyridine unit with carbon monoxide in the presence of a primary alcohol as nucleophile and a tertiary amine as base. Monofunctionalization of disubstituted compounds is realized by reaction in ethanol under mild conditions (70 degrees C, 1 atm
bipyridine‐based (25 nm) complexes towards the visible region (up to 440 nm). Moreover, the substitution of the terpyridine–tetrazolate system with different groups in the ligand series L3–L6 has a very important effect on both absorption spectra and luminescence efficiency of their lanthanidecomplexes. The tetrazole‐based ligands L1 and L3–L8 sensitize efficiently the luminescent emission of lanthanide ions in the
Facile and Multistep Synthesis of Functionalized Nitroxide Radicals Containing a Bipyridine Frame
作者:Raymond Ziessel、Abdelkrim El-ghayoury
DOI:10.1055/s-2000-8730
日期:——
The synthesis of stable bipyridine substituted nitronyl-nitroxide (NIT) or imino-nitroxide (IM) is reported. These methyl or ethynyl functionalized compounds have been prepared from the bromo-substituted analogues by a carboalkoxylation reaction catalyzed by low valent palladium(0) using carbon monoxide in the presence of a primary alcohol as nucleophile and a tertiary amine as base. In the case of the 6,6′-dibromo-2,2′-bipyridine, a quite selective mono-carboethoxylation reaction is achieved under mild conditions (70 °C, 1 atmosphere CO). Stepwise reduction of the resulting esters with sodium borohydride, followed by Swern oxidation, affords the corresponding carbaldehydes in good yield. Furthermore, these derivatives were used in a multistep protocol to prepare hybrid molecules bearing both an ethynyl group and a nitroxide free radical. The synthetic methods reported herein provide a practical methodology to the rational design of ligands bearing different kinds of functionalities.