Isomerization and Sulfodeprotonation in the Reaction of 1,6-Oxidoannulene, 1,6-Iminoannulene, Their Isomers 1-Naphthol and 1-Aminonaphthalene, and 11-Oxo-1,6-methanoannulene with SO3

Article abstract of DOI:10.1021/jo00363a030

The reactions of 1-naphthol (3), 1-aminonaphthalene (10), and 1,6-oxido- (1), 1,6-imino- (2), and 11-oxo-1,6-methano<10>annulene (15) with SO3 in aprotic solvents have been studied.With 3 the initial product is 1-naphthyl hydrogen sulfate (4), which is slowly converted into the 1-naphthol-2- (5) and -4-sulfonic acid (6) via O-desulfonation and C-sulfonation on using is less than or equal to 1 equiv of SO3, but via C-sulfonation and O-desulfonation if the SO3 is in a large excess.It is suggested that on using is less than or equal to 1 equiv of SO3 the conversion of 4 into the 2-sulfonic acid 5 proceeds intramolecularly.The annulene 1 with SO3 in dioxane initially yields 1-naphthol and its hydrogen sulfate (4), which at temperatures >-30 deg C undergo ring sulfonation (vide supra).The nitrogen-containing substrates behave quite similarly to their oxygen analogues in that both 10 and 2 yield 10-2-SO3H, 10-4-SO3H, and 10-2,4-(SO3H)2.With 2, the initial product is the N-sulfonic acid 9.The ketone 15 undergoes ring substition with formation of the 2-sulfonic and 2,7-disulfonic acids.Mechanisms have been presented to rationalize the skeletal rearrangements of the annulenes 1 and 2.