. The general structure is R1R2C=NR3+O- where R3 is different from H. A nitrone is 1,3-dipole in 1,3-dipolar cycloadditions. It reacts with alkenes to an isoxazolidine: » One example of this reaction type is the reaction of various Baylis-Hillman adducts with C-Phenyl-N-methylnitrone forming an isoxazolidine in which R1 is phenyl, R2 is hydrogen and R3 is a methyl group . Nitrones react with terminal alkynes and a copper salt to beta-lactam. This reaction is also called the The Kinugasa reactio… (More on Nitrone)