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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
One-step route to tricyclic fused 1,2,3,4-tetrahydroisoquinoline systems via the Castagnoli-Cushman protocol
Aleksandar Pashev1,2, Nikola Burdzhiev1, Elena Stanoeva1
1Sofia University "St. Kliment Ohridski", Faculty of Chemistry and Pharmacy, 1, James Bourchier ave., 1164 Sofia, Bulgaria.
Abstract:
The Castagnoli-Cushman reaction of 3,4-dihydroisoquinolines with glutaric anhydride, its oxygen and sulfur analogues was investigated as a one-step approach to the benzo[a]quinolizidine system and its heterocyclic analogs. An extension towards the pyrrolo[2,1-a]isoquinoline system was achieved with the use of succinic anhydride. The results are evidence of an unexplored method for the access of the aforementioned tricyclic annelated systems incorporating a bridgehead nitrogen atom. The structures and relative configurations of the new compounds were established by means of 1D and 2D NMR techniques. The reactions between 1-methyldihydroisoquinoline and glutaric, diglycolic and succinic anhydrides yielded unexpected isoquinoline derivatives containing an exocyclic double bond. The compounds prepared bear the potential to become building blocks for future synthetic bioactive molecules.
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