Novel electrophilic ipso acylation - Detosylation reaction of pyrroles
A pyrrole and two pyrroloindoles that are substituted with a p-toluenesulfonyl group undergo an ipso acylation - detosylation reaction with acid chlorides and aluminum chloride to afford the corresponding acyl-substituted pyrroles and pyrroloindoles.
Pelkey, Erin T.,Gribble, Gordon W.
p. 1338 - 1342
(2007/10/03)
Pyrrole chemistry. XXVIII. Substitution reactions of 1-(phenylsulfonyl)pyrrole and some derivatives
The preparative value of the 1-(phenylsulfonyl) N-blocking and directing group for the synthesis of 3-acylpyrroles has been further evaluated.Acetylation and benzoylation are strongly regiospecific and give good yields.However, the regiospecificity is not general and other substitution reactions give mixtures of 2- and 3-substitution or even mostly 2-substitution.Friedel and Crafts tert-butylation gives 3-tert-butyl-1-(phenylsulfonyl)pyrrole and provides a useful route to tert-butylpyrrole, but ethylation and isopropylation give mixtures.Acylations of 2- and 3-alkyl-1-(phenylsulfonyl)pyrroles show little evidence of useful regiospecificity.