Stereoselective Synthesis of Polycycles Containing an Aziridine Group: Intramolecular aza‐Diels–Alder Reactions of Unactivated 2H‐Azirines with Unactivated Dienes

Abstract

Vinyl azide with a pendent diene can undergo thermal decomposition to a related azirine intermediate, which was used immediately in an intramolecular aza-Diels-Alder reaction to furnish an aziridine-containing trans-fused tricyclic core structure with excellent stereoselectivity. The method provides a facile entry to complex polycyclic alkaliods which can be further elaborated by ring-opening reactions and ring expansion of the aziridine moiety, as well as by dihydroxylation of the alkene group.

Facile Multicomponent Polymerizations toward Unconventional Luminescent Polymers with Readily Openable Small Heterocycles

“…The presence of large numbers of small-ring heterocycles in a polymer backbone is very likely to endow the corresponding polymeric material with a variety of new interesting properties and advanced functionalities. ,− For example, the ring strain of these small cyclic units in polymer chains may enable the polymer to be transformed into new forms or structures with distinctive properties and performance in response to external stimuli. , On the other hand, the introduction of numerous heteroatoms could bring the resulting polymers with intriguing biological activities or photophysical properties and potential applications in biomedical science, advanced optics, smart sensing materials, etc. − For instance, some nonconjugated but heteroatom-rich natural products like starch, cellulose, protein, etc., and synthetic polymers including poly­(amidoamine)­s, polysiloxanes, poly­(maleic anhydride), etc., , have been reported to show clusteroluminescence. They can emit visible light upon UV excitation in the condensed state even without any classic conjugated structures.…”

Facile Multicomponent Polymerization and Postpolymerization Modification via an Effective Meldrum's Acid‐Based Three‐Component Reaction

“…During the multicomponent polymerization, two different heterocycles of Meldrum's acid and indole were incorporated into the polymer chain directly from simple monomers, and the resultant polymer structures are inaccessible by other synthetic approaches. The presence of large numbers of heterocycles in polymer chains is likely to endow the polymers with new interesting properties [ 22,42–44 ] . Especially, the indole moieties in polymer backbones endow polymers many useful applications, such as electrochemical devices, [ 45 ] DNA detection [ 46 ] and antibacterial materials.…”

Visible-Light Promoted Selective Imination of Unactivated C–H Bonds via Copper-nitrene Intermediates for the Synthesis of 2H-Azirines

“…Generally, the aliphatic moieties with tertiary carbons ( 2e – 2m ) to form C–N bond outperformed secondary carbons ( 2a – 2d ) under standard conditions. It was worth noticing that alkenes ( 2d , 2g ) including terpene ( 2h ) were tolerated well to give excellent yields of the product (up to 82%), which demonstrated the potential application of the strategy in synthesis of complex compounds through inter/intramolecular cyclization reactions . The good yields of the reaction performed at both microscale and gram scale identified the potential application of the method in organic synthesis ( 2i ).…”