β,γ-trans-selective γ-butyrolactone formation via homoenolate cross-annulation of enals and aldehydes catalyzed by sterically hindered N-heterocyclic carbene

Highly sterically hindered N-heterocyclic carbenes (NHCs), can be readily prepared from the corresponding anilines, and serve as organocatalysts in NHC-catalyzed homoenolate cross-annulation of alpha,beta-enals and aryl aldehydes. This catalysis enables the convergent construction of beta,gamma-trans-disubstituted gamma-butyrolactones that are an important class of molecules in synthetic and medicinal chemistry. The steric features of N-aryl substituents contribute to the selectivity and electronic ones affected the efficiency of this reaction, which proceeds with high diastereoselectivity and affords a variety of beta,gamma-diaryl-gamma-butyr-olactones in up to 91% yield with up to 1:99 dr. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study demonstrates the use of highly sterically hindered N-heterocyclic carbenes as catalysts in the cross-annulation reaction of alpha,beta-enals and aryl aldehydes, leading to the convergent construction of beta,gamma-trans-disubstituted gamma-butyrolactones.