Key points are not available for this paper at this time.
Enantioselectivity through H bonding: An unprecedented 4+3 annulation of enals with o-quinone methides catalyzed by N-heterocyclic carbenes (NHCs) to give benzo-ε-lactones is described. High to excellent enantioselectivity was achieved by using a chiral triazolium NHC having a free OH group, which participates in a hydrogen-bonding interaction with the substrate.
Lv et al. (Mon,) studied this question.