Evolutionary metabolomics of specialized metabolism diversification in the genus Nicotiana highlights N-acylnornicotine innovations.

Specialized metabolite (SM) diversification is a core process to plants' adaptation to diverse ecological niches. Here, we implemented a computational mass spectrometry-based metabolomics approach to exploring SM diversification in tissues of 20 species covering Nicotiana phylogenetics sections. To markedly increase metabolite annotation, we created a large in silico fragmentation database, comprising >1 million structures, and scripts for connecting class prediction to consensus substructures. Together, the approach provides an unprecedented cartography of SM diversity and section-specific innovations in this genus. As a case study and in combination with nuclear magnetic resonance and mass spectrometry imaging, we explored the distribution of N-acylnornicotines, alkaloids predicted to be specific to Repandae allopolyploids, and revealed their prevalence in the genus, albeit at much lower magnitude, as well as a greater structural diversity than previously thought. Together, the data integration approaches provided here should act as a resource for future research in plant SM evolution.

Synthesis of Non-natural Aza-Iridoids via Ynamides and Molecular Networking-Based Tracing of Their In Planta Bioconversion.

A synthesis of new-to-nature aza-iridoids via ynamides is presented. ZrCl4 proved to be the best acid to perform this transformation. Various ynamides were accommodated, and seco-iridoids could be obtained as well. Aza-iridoids were infiltrated into leaves of Scrophularia Nodosa, an iridoid-producing plant species. High-resolution mass spectrometry coupled to computational metabolomic approaches was employed for the detection of aza-iridoid bioconversion products.

Copper-Catalyzed Synthesis of Terminal vs. Fluorine-Substituted N-Allenamides via Addition of Diazo Compounds to Terminal Ynamides.

A copper-mediated coupling reaction between ynamides and diazo-compounds to produce N-allenamides is reported for the first time. This method enables facile and rapid access to terminal N-allenamides by using commercially available TMS-diazomethane with wide functional group compatibility on the nitrogen. Furthermore, the ubiquity of molecules containing a fluorine moiety in medicine, in agricultural, and material science requires the continuous search of new building blocks, including this unique surrogate. The CuI/diazo protocol was successfully applied to the synthesis of fluorine-substituted N-allenamides. DFT calculations provided insights in the mechanism involved.