Brønsted acid-catalyzed stereoselective [4+3] cycloadditions of ortho-hydroxybenzyl alcohols with N,N'-cyclic azomethine imines.

The first [4+3] cycloaddition of ortho-hydroxybenzyl alcohols has been established by making use of N,N'-cyclic azomethine imines as suitable 1,3-dipoles under Brønsted acid catalysis. By using this strategy, biologically important seven-membered heterocyclic scaffolds have been constructed in good yields and excellent diastereoselectivities (up to 92% yield, most >95 : 5 dr).