Aza-Prins Cyclization on Ketones to Access Piperidines with Tetrasubstituted Carbon Stereocenters

International audienceThe aza-Prins cyclization in presence of a variety of aliphatic, aromatic, and heterocyclic ketones is disclosed. The developed method allows an access to diverse C-2 functionalized piperidines, bearing a tetrasubstituted or spiranic carbon stereocenter, in a range of 30 to 87% yields. When diastereomers were formed, the trans isomer was identified as the major product

Fractionation and Extraction Optimization of Potentially Valuable Compounds and Their Profiling in Six Varieties of Two <i>Nicotiana</i> Species

There is an increasingly urgent call to shift industrial processes from fossil fuel feedstock to sustainable bio-based resources. This change becomes of high importance considering new budget requirements for a carbon-neutral economy. Such a transformation can be driven by traditionally used plants that are able to produce large amounts of valuable biologically relevant secondary metabolites. Tobacco plants can play a leading role in providing value-added products in remote areas of the world. In this study, we propose a non-exhaustive list of compounds with potential economic interest that can be sourced from the tobacco plant. In order to optimize extraction methodologies, we first analyzed their physico-chemical properties using rapid solubility tests and high-resolution microfractionation techniques. Next, to identify an optimal extraction for a selected list of compounds, we compared 13 different extraction method–solvent combinations. We proceeded with profiling some of these compounds in a total of six varieties from Nicotiana tabacum and Nicotiana rustica species, identifying the optimal variety for each. The estimated expected yields for each of these compounds demonstrate that tobacco plants can be a superior source of valuable compounds with diverse applications beyond nicotine. Among the most interesting results, we found high variability of anatabine content between species and varieties, ranging from 287 to 1699 µg/g. In addition, we found that CGA (1305 µg/g) and rutin (7910 µg/g) content are orders of magnitude lower in the Burley variety as compared to all others