title: N-heterocyclic carbene (NHC)-catalyzed/Lewis acid mediated conjugate umpolung of alkynyl aldehydes for the synthesis of butenolides: a formal [3+2] annulation.
abstract: 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 C-C bond-forming step.
authors: State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu, 730000, PR China.
authors: Jing
authors: J
authors: Qi
authors: Xingang
authors: X
authors: Xie
authors: Runfeng
authors: R
authors: Han
authors: Donghui
authors: D
authors: Ma
authors: Juan
authors: J
authors: Yang
authors: Xuegong
authors: X
authors: She