Nitrones. 6. Reactions of Nitrones with Cyclic Phosphonates. Influence of the Phosphonate Ring Size upon the Course of the Reaction

Article abstract of DOI:10.1021/jo00345a035

Nitrones, 5,5-dimethyl-Δ¹-pyrroline N-oxide (5), and 3,4-dihydroisoquinoline N-oxide (6) were reacted with the five-membered cyclic phosphonates 2-<(ethoxycarbonyl)methyl>-2-oxo-4,5-dimethyl-1,3,2-dioxaphospholane (1) and 2-(cyanomethyl)-2-oxo-4,5-dimethyl-1,3,2-dioxaphospholane (2) and with the six-membered cyclic phosphonates 2-<(ethoxycarbonyl)methyl>-2-oxo-5,5-dimethyl-1,3,2-dioxaphosphorinane (3) and 2-(cyanomethyl)-2-oxo-5,5-dimethyl-1,3,2-dioxaphosphorinane (4).The reactions of the five-membered phosphonates gave aziridines as products, except that of 6 and 2.The reactions of the six-membered phosphonates gave exclusively or predominantly enamines.The reactions of C-phenyl-N-methylnitrone (7) with 2 gave only trans-1-methyl-2-cyano-3-phenylaziridine (22).Cyclic phosphates 2-hydroxy-2-oxo-4,5-dimethyl-1,3,2-dioxaphospholane (20) and 2-hydroxy-2-oxo-5,5-dimethyl-1,3,2-dioxaphosphorinane (21) were isolated as byproducts from the reactions of the corresponding phosphonates.