N-Heterocyclic Carbene Catalyzed Transformations of 3-Halopropenals to the Equivalents of β-Acylvinyl Anions
摘要:
3-Halopropenals 1 can behave as an alternative equivalent of beta-acylvinyl anions (I) in the presence of N-heterocyclic carbene precursor (IPr center dot HCl) and DBU to afford cyclic alpha,beta-unsaturated carbonyl derivatives, butenolides 4 and pyrazolone 6, after cyclization with 2 and 5, respectively.