N-Heterocyclic Carbene (NHC)-Catalyzed/Lewis Acid Mediated Conjugate Umpolung of Alkynyl Aldehydes for the Synthesis of Butenolides: A Formal [3+2] Annulation
作者:Jing Qi、Xingang Xie、Runfeng Han、Donghui Ma、Juan Yang、Xuegong She
DOI:10.1002/chem.201204386
日期:2013.3.25
Reverse to success! A new formal [3+2] annulation reaction combining alkynyl aldehydes and β,γ‐unsaturated α‐ketoesters has been disclosed by using a NHC‐catalyzed/Lewis acid mediated strategy. This cooperative catalysis strategy first allows the “allenolate” intermediate as a nucleophilic synthon at the β‐position to react with activated electrophilic reagents by an addition reaction as the key CC