Metal Free Sulfonylative Spirocyclization of Alkenyl and Alkynyl Amides
<i>via</i>
Insertion of Sulfur Dioxide
作者:Akshay M. Nair、Indranil Halder、Salman Khan、Chandra M. R. Volla
DOI:10.1002/adsc.201901321
日期:2020.1.7
of azaspiro[4,5]‐decanes and azaspiro[4,5]‐trienones by the radical cascade spirocyclization of N‐benzylacrylamides or N‐arylpropiolamides respectively. These reactions proceed under metal freeconditions and involve in situ generation of aryl sulfonyl radicals from DABSO and aryl diazonium salts. Furthermore, a catalystfreevisiblelight mediated protocol was developed for the sulfonylative spirocyclization
Palladium-catalyzed difunctionalization/dearomatization of <i>N</i>-benzylacrylamides with α-carbonyl alkyl bromides: facile access to azaspirocyclohexadienones
作者:Chuan-Chong Peng、Li-Jun Wu、Shao-Feng Pi
DOI:10.1039/d1ob01405f
日期:——
An efficient palladium-catalyzed difunctionalization/dearomatization of N-benzylacrylamides with α-carbonyl alkyl bromides as alkyl radical precursors has been described. Various α-carbonyl alkyl bromides, including α-bromoalkyl esters and ketones, reacted smoothly to provide important azaspirocyclohexadienones in moderate to excellent yields. In addition, mechanistic studies suggested that the reaction
azaspirocyclohexadienones. Notably, polyhaloalkanes are employed as efficient alkyl radical sources via the cleavage of C(sp3)–H bonds. This protocol undergoes a cascade radicaladdition and intramolecular cyclization/dearomatization process, and enables the easy construction of multiple chemical bonds and a spiro ring in a single reaction.