Exploring the Reactivity of Substituted [(Allyloxy)methyl]phosphonates in Cycloaddition and Coupling Reactions

This paper describes the versatility of substituted [(allyl­oxy)methyl]phosphonates to open the way to the synthesis of original phosphonated molecules with heterocyclic architectures. In 1,3-dipolar cycloaddition reactions with nitrile oxides, nitrile imines, and nitrones, these [(allyloxy)methyl]phosphonates react as dipolarophiles to give, regioselectively, the corresponding isoxazolines, pyrazolines, and isoxazolidines. Transition-metal-catalyzed reactions, including inter- or intramolecular Heck coupling, provided access to cinnamyl- and indenyl-linked moieties and phosphonated benzo-fused oxacycles, respectively. Additionally, ring-closing metathesis reactions enabled the synthesis of 2,5-dihydrofurans with the phosphonate group at the anomeric position. In this work, 51 novel phosphorylated heterocyclic compounds, which may find significance in the pharmaceutical and agrochemical fields, were prepared.