Palladium-Catalyzed Cross-Coupling Reactions of Carboxylic Anhydrides with Organozinc Reagents
作者:Donghui Wang、Zhaoguo Zhang
DOI:10.1021/ol035801w
日期:2003.11.1
[reaction: see text] Negishi-type cross-coupling reaction was effected by employing organozincs and anhydrides or mixedanhydrides that formed in situ fromsodiumsalts of the corresponding acids and ethyl chloroformate under the catalysis of palladium(0). A general method for preparing symmetrical/unsymmetrical ketones was developed.
Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
The title compounds (3) have been prepared and their chemical properties studied. With iodine they give aryloxymethyl aryloxyacetates (4) through the intermediacy of aryloxyacetyl hypoiodites and α-iodoanisoles. The former are unstable but have been trapped with pyridine to give N-iodopyridinium aryloxyacetates, whereas the latter are stable and react independently with compounds (3) to afford the
Transformation of lignin model compounds to<i>N</i>-substituted aromatics<i>via</i>Beckmann rearrangement
作者:Yinling Wang、Yiman Du、Jianghua He、Yuetao Zhang
DOI:10.1039/c8gc00920a
日期:——
Here we present the highly effective cleavage of C–C bonds in lignin modelcompounds for the production of N-substituted aromatics in up to 96% total yield, including benzonitriles and amides, via oxime formation followed by Beckmann rearrangement (BR). The amides could be further hydrolyzed to anilines (>92% yield) and carboxylic acids (>90% yield), respectively. In addition, the employment of a substrate