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Updated: Jul 14, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
A Rapid Aza-Bicycle Synthesis from Dendralenes and Imines
Yi-Min Fan1, Josemon George1, Jiao Yu J Wang2
1Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory 2601, Australia.
Abstract:
The diene-transmissive 2-fold Diels-Alder sequence between carbon-based dienophiles and [3]dendralenes is becoming an established method for polycarbocycle synthesis. Here, we demonstrate for the first time that imines are competent participants in intermolecular formal [4 + 2] cycloadditions with dendralenes. After a second Diels-Alder process with a carbadienophile, hexahydro- and octahydro-isoquinoline structures are formed. The formal aza-Diels-Alder reaction, which requires Lewis acid promotion, proceeds in high regio- and stereoselectivity under optimized conditions. ωB97XD/Def2-TZVP//M06-2X/6-31+G(d,p) calculations reveal a stepwise ionic mechanism for the formal aza-dienophile cycloadditions and also explain an unexpected Z → E olefin isomerization of a non-reacting C═C bond in the first formal cycloaddition.
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