The reactivity of sulfur-centred radicals towards TMIO (1,1,3,3-tetramethyl-2,3-dihydroisoindol-2-yloxyl). A new type of radical fragmentation reaction
F. Aldabbagh et al., The reactivity of sulfur-centred radicals towards TMIO (1,1,3,3-tetramethyl-2,3-dihydroisoindol-2-yloxyl). A new type of radical fragmentation reaction, AUST J CHEM, 54(5), 2001, pp. 313-318
The thiyl radicals derived from 2-mercaptoethanol and thiophenol were found
to undergo a complex series of reactions with 1,1,3,3-tetramethyl-2,3-dihy
droisoindol-2-yloxyl (TMIO). Thus, treatment of 2-mercaptoethanol with di-t
-butyl peroxyoxalate (DTBPO) in the presence of TMIO produced two N-S compo
unds-a sulfoxamide and a sufonamide-not the expected N-O-S adduct. The reac
tion between thiophenol and TMIO, which proceeded at a reasonable rate in t
he absence of DTBPO, produced 1,1,3,3-tetramethyl-2,3-dihydroisoindolin and
its corresponding phenylsulfoxamide, diphenyl disulfide, phenylsulfinic ac
id, and 1, 1,3,3-tetramethyl-2,3-dihydroisoindol-2-ylphenylsulfonate (the a
dduct of TMIO and the phenylsulfonyl radical). The mechanism of formation o
f these products, and the use of TMIO for trapping S-centred radicals, are
discussed. A new radical fragmentation process, which appears to be general
for aminoxyl adducts of electron-rich systems, is described.