ON THE REACTION OF AMINOXYLS WITH DIOXIRANES

In the reactions of dimethyldioxirane (la) and methyl(trifluoromethyl) dioxirane (Ib) with 2,2,6,6-tetramethylpiperidinyl-1-oxyl (2) (TEMPO) in acetone, the corresponding methoxyamine 1-methoxy-2,2,6,6-tetrameth ylpiperidine (5) is produced in greater than or equal to 98% yield, bo th in air and under N-2, and in the absence or presence of a hydrocarb on (adamantane). Kinetic experiments show that aminoxyl 2 triggers the radical decomposition of the dioxirane, in addition to scavenging met hyl radicals derived therefrom. The reactions of an aminoxyl less pron e to oxidation, namely ,2-dihydro-2-methyl-2-phenyl-3H-indol-3-one-1-o xyl (4), with dioxiranes la and Ib in acetone have also been studied. In these cases, not only is the corresponding methoxyamine 8a produced (yield 12-16%), but quinoneimine-N-oxides 10 (yield 12-21%) and 11 (y ield 18-19%) are also formed. Furthermore, significant amounts (8-14%) of the amine 9 (the product of deoxygenation of 4) can be isolated. T hese observations provide useful information concerning the free-radic al mechanism that follows the initial attack by the aminoxyl at the di oxirane.