The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

Abstract
The three-component reaction of isoquinolines, dialkyl acetylenedicarboxylates, and 5,6-unsubstituted 1,4-dihydropyridines in acetonitrile at room temperature afforded functionalized isoquinolino[1,2-f][1,6]naphthyridines in good yields and with high diastereoselectivity. More importantly, the formal [2 + 2] cycloaddition reaction of dialkyl acetylenedicarboxylates and 5,6-unsubstituted 1,4-dihydropyridines in refluxing acetonitrile gave unique 2-azabicyclo[4.2.0]octa-3,7-dienes as major products and 1,3a,4,6a-tetrahydrocyclopenta[b]pyrroles as minor products via further rearrangement.

Beilstein J. Org. Chem. 2023, 19, 982–990. doi:10.3762/bjoc.19.73

Source: Beilstein Journal of Organic Chemistry - June 29, 2023 Category: Chemistry Authors: Beilstein Journal of Organic Chemistry - Syndicated Feeds Tags: 1,4-dihydropyridine electron-withdrawing alkyne formal [2 2] cycloaddition Huisgen ' s 1,4-dipole isoquinoline isoquinolino[1,2-f][1,6]naphthyridine Full Research Paper Source Type: research