Non-Decarboxylative Ruthenium-Catalyzed Rearrangement of 4-Alkylidene-isoxazol-5-ones to Pyrazole- and Isoxazole-4-carboxylic Acids
Camilla Loro, L. Molteni, Marta Papis, Leonardo Lo Presti, Francesca Foschi, Egle M. Beccalli, Gianluigi Broggini
Abstract
, without any additive, afforded pyrazole- and isoxazole-4-carboxylic acids, respectively. The presence of an intramolecular H-bond in these substrates was the key to divert the classical mechanism toward a ring-opening non-decarboxylative path that is expected to generate a vinyl Ru-nitrenoid intermediate, the cyclization of which affords the rearranged products. A gram scale protocol demonstrated the synthetic applicability of this transformation.
Topics & Concepts
IsoxazoleChemistryIntramolecular forcePyrazoleCatalysisRing (chemistry)Medicinal chemistryDecarboxylationRutheniumCombinatorial chemistryStereochemistryOrganic chemistrySynthetic Organic Chemistry MethodsSynthesis and Catalytic ReactionsCatalytic C–H Functionalization Methods