Bromination of Isoquinoline, Quinoline, Quinazoline and Quinoxaline in Strong Acid

William Dalby Brown; Alex Haahr Gouliaev

doi:10.1055/s-2002-19314

PAPER

Bromination of Isoquinoline, Quinoline, Quinazoline and Quinoxaline in Strong Acid

William Dalby Brown^a, Alex Haahr Gouliaev*^b
^a Department of Chemistry, University of Copenhagen, Copenhagen, 2100, Denmark
^b Nuevolution A/S, Copenhagen, 2100, Denmark
Fax: +4570200986; e-Mail: ahg@nuevolution.com;

Abstract

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Abstract

Bromination of benzazines and benzodiazines most often gives a mixture of products. In this paper, we show that isoquinoline (1) may be regioselectively monobrominated in concentrated H₂SO₄ using NBS or in CF₃SO₃H using N,N’-dibromoisocyanuric acid (DBI) to give 5-bromoisoquinoline (2). The bromination was found to be highly sensitive to the choice of brominating agent, acid, temperature and concentration. Quinoline, quinazoline and quinoxaline may be brominated likewise, although with the strong regioselectivity reserved to isoquinoline.

Key words

bromination - electrophilic aromatic substitution - regioselective - benzazines - benzodiazines

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References

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