Abstract
A series of bicyclic nitroxides, (
3aR(S),6aR(S))
-1-X-1,3,3-triethyloctahydropyrrolo[3,4-c]pyrrol-2-oxyls, where X = Et or t-Bu, have been prepared from the corresponding 3,4-disubstituted bis(hydroxymethyl)pyrrolidine-1-oxyls, which are among the most stable nitroxides known. The formation of this bicyclic system occurs upon
in situ
generation of
trans
-3-(aminomethyl)-4-(((methylsulfonyl)oxy)methyl)pyrrolidin-1-oxyls by various methods. Although the resulting nitroxides have highly strained
trans
-3,7-diazabicyclo[3.3.0]octane scaffold, they demonstrate high resistance to reduction with ascorbate (k
2
~ 10
-3
–10
-4
M
-1
s
-1
). A number of bicyclic conformationally rigid spin labels have been prepared.