Indole oxidation

[moracca]

Hey. I was recently cruising around pubmed, and came across this article: here. In short, they use chloroperoxidase to oxidize indole. I was at first interested by this as it might make an easier synth for the 4-HO-X trypts, however after raeding the article a bit more, i found that the hydroxy group is added onto the carbon right next to the Nitrogen on the indole ring (position 2 if we count N as position one, and count counterclockwise). My question is this: what determines where the hydroxy funtional group is added onto the ring? Is there any way to force it somewhere else? and what if there was the ethylamine group on carbon 3 already? would the HO group still go on position 2? or somewhere else? I have a very very basic understanding of organic chem, and i know a small amount about orth, para, and meta directors if we were talking about a benzene ring, however i dont really know what makes this oxidation reaction tick, so if anyone could enlighten me, it would be much appreciated. Thanks so much!

//moracca

 

[EN21]

Indole is very sensitive towards oxidation and it occurs either in position 2 (as in this article) to form an amide or in position 3 where it can form a 3,3-disubstituted compound with the double bond between the indole N and position 2 (loss of the indole NH.)
All those oxidations do not yield in any useful (4-or 5 position) substitution pattern.
It ia a pity, but 4 or 5-hxdroxylated indoles can not be synthesized from normal indole by plane oxidation.