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I’m happy to share two recent papers on our ketenyl anion chemistry: In @jacs.acspublications.org, we report the isolation of the long-elusive pyridylketenyl🔥 anion, an ideal precursor for N-fused heterocycles. Congrats to Stephan for taming this challenging species. doi.org/10.1021/jacs...

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The Pyridylketenyl Anion: Entry to Diverse N-Heterocycles The pyridylketene has previously been isolated via matrix isolation and demonstrated potential in the synthesis of N-heterocycles. Herein, we report the synthesis and isolation of the pyridylketenyl anion through conventional synthetic methods, involving metalation and subsequent carbonylation of the readily available 2-pyridyl ylide. Quantum chemical calculations reveal extensive delocalization of the negative charge across the entire molecular framework, resulting in multiple nucleophilic sites that are best described by a series of resonance structures. IR spectroscopic and X-ray diffraction data corroborate this electronic structure, indicating a markedly compressed C–C–C–O moiety. The pronounced charge delocalization enables diverse reactivities and promotes cyclization pathways involving the pyridine nitrogen. Accordingly, the pyridylketenyl anion serves as a versatile precursor for the construction of heterocycles featuring triazolone, quinolizine, and indolizine motifs, underscoring its broad applicability as a building block in heterocycle synthesis. https://doi.org/10.1021/jacs.6c03327