Carbene Radicals in Cobalt(II)-Porphyrin-Catalysed Carbene Carbonylation Reactions; A Catalytic Approach to Ketenes
作者:Nanda D. Paul、Andrei Chirila、Hongjian Lu、X. Peter Zhang、Bas de Bruin
DOI:10.1002/chem.201301731
日期:2013.9.23
One‐pot radicals: Cobalt(III)–carbene radicals, generated by metallo‐radical activation of diazo compounds and N‐tosylhydrazone sodium salts with cobalt(II) complexes of porphyrins, readily undergo radical addition to carbon monoxide, allowing the catalytic production of ketenes. These ketenes subsequently react with various amines, alcohols and imines in one‐pot tandem transformations to produce differently
Pd-Catalyzed Carbonylation of Diazo Compounds at Atmospheric Pressure: A Catalytic Approach to Ketenes
作者:Zhenhua Zhang、Yiyang Liu、Lin Ling、Yuxue Li、Yian Dong、Mingxing Gong、Xiaokun Zhao、Yan Zhang、Jianbo Wang
DOI:10.1021/ja107351d
日期:2011.3.30
and affects the diastereoselectivity of the β-lactam products by assisting isomerization of the addition intermediate. On the other hand, the acylketenes generatedfrom the Pd-catalyzed carbonylation of α-diazoketones react with imines in a formal [4 + 2] cycloaddition manner to afford 1,3-dioxin-4-one derivatives. This straightforward carbonylation provides a new approach toward highly efficient catalytic
and recyclable coupling reagent NDTP, which could activate the carboxylic acids via acyl thiocyanide and enable the rapid amide and peptidesynthesis at very mild conditions. In addition, the methodology was compatible with Fmoc-SPPS, which may provide an alternative to peptide manufacturing.
The challenging transamidation of unactivated tertiary amides using equivalent amounts of amines has been accomplished via cooperative acid/iodide catalysis. The method provides a novel manifold to re-route the reactivity of unactivated and unreactive N,N-dialkyl amides through reactive acyl iodide intermediates, representing a powerful new activation mode of unactivated amide bonds.