Intramolecular [3+2]-Cycloaddition of Salicylaldehydes-Based Cyclic Azomethine Imines to Access Novel Tetrahydrochromeno[4,3-C]pyrazolo[1,2-a]pyrazol-9-ones

An efficient intramolecular [3 + 2]-cycloaddition of in situ-formed salicylaldehyde-based N,N'-cyclic azomethine imines was successfully developed to access novel tetracyclic skeleton bearing three contiguous stereogenic centres. This established protocol features high functional-group tolerance, excellent chemical yields, good diastereoselectivities, and variable reaction conditions. (C) 2021 Elsevier Ltd. All rights reserved.