Superacid-Promoted Reactions of α-Ketoamides and Related Systems
作者:Kiran Kumar Solingapuram Sai、Pierre M. Esteves、Eduardo Tanoue da Penha、Douglas A. Klumpp
DOI:10.1021/jo801208m
日期:2008.9.1
The superacid-promoted reactions of alpha-hydroxy and alpha-ketoamides have been studied. Ionization of these compounds leads to varied aryl-substituted oxyindole products. In some cases, electrocyclization can lead to substituted fluorene products. Dicationic, superelectrophilic intermediates are proposed as intermediates leading to the products from alpha-hydroxy and alpha-ketoamides.
Preparation of 3,3-Diaryloxindoles by Superacid-Induced Condensations of Isatins and Aromatics with a Combinatorial Approach
作者:Douglas A. Klumpp、Ka Yeun Yeung、G. K. Surya Prakash、George A. Olah
DOI:10.1021/jo980588g
日期:1998.6.1
3,3-Diaryloxidoles are prepared in high yields (62-99%) by reaction of isatin or substituted isatins with aromatics in triflic acid. The reaction shows a significant dependence on acid strength which suggests the formation of diprotonated, superelectrophilic intermediates. Reaction of isatin, benzene, and acid systems of varying strength (composed of CF3SO3H and CF3CO2H) showed that the acid strength must be more acidic than H-0 = -11.5 for complete conversion to product. Reaction of isatins with mixtures of aromatics allows for the preparation of libraries of 3,3-diaryloxindole products by combinatorial synthesis.