Hydroxylation and bromination of indolines and tetrahydroquinoline in superacids

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HYDROXYLATION AND BROMINATION OF INDOLINES AND TETRAHYDROQUINOLINE IN SUPERACIDS C. Berrier, J. C. Jacquesy*, M. P. Jouannetaud and A. Renoux Laboratoire de Chimie XII, U.A. C.N.R.S. no 489, “SynthBse et RBactivit6 de Produits Naturels”, Facultk des Sciences 40, Avenue du Recteur Pineau, 86022 Poitiers (France)

In superacid are monohydroxylated

SbFS-HF,

indolines 1 and IJ, and tetrahydroquinoline

by hydrogen

SUBSTRATE

peroxide

and monobrominated

by bromine.

HYDROXYLATION

BROMINATION

position

position - %

- %

III

42

@cjz 5&f It k Ir

39@-f

I$

44

0 o-3

22

0 00

27

N

N I

I:

-III

H

In the reaction ions with the electrophile stitution

occurs

deactivating

conditions (protonated

ortho or para

protonated

these substrates hydrogen

to the alkyl group which

nitrogen.

are reacting

peroxide

as ammonium

H302+ or 'Br+'). Subis winning

out over the

41

The brominating drance

than H302+

agent appears

(ortho/F -

to be more sensitive

ratio of Br-derivatives

to steric

< ortho/para

hin-

ratio of OH-

derivatives). For a given higher

reaction

the observed

in the tetrahydroquinoline

the result of the Mills-Nixon

ortho/para

than in the indoline

effect

substitution

ratio

is

series and this might

(o/p -- ratio of hydroxylation

be

is the same

on III and on o-toluidine).

OH

0 NH2 + a In superacids, or degradation reactive

hNH2+HoaNH2 428

21%

protonation

and electrophilic

in usual conditions.

protects

substitution

the nitrogen occurs

group from oxidation

at positions

normally

un-