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Synthesis 2009(21): 3661-3671  
DOI: 10.1055/s-0029-1217008
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Functionalization of 4,5-Dihydrobenzo[g]indazoles Using Magnesium- or Zinc-Heterocyclic Intermediates

Christina Despotopouloua, Camille Gignouxb, Darryl McConnellb, Paul Knochel*a
a Department Chemie und Biochemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany
Fax: +49(89)218077680; e-Mail: paul.knochel@cup.uni-muenchen.de;
b Boehringer Ingelheim Austria GmbH, Medicinal Chemistry, Dr. Boehringer-Gasse 5-11, 1121 Vienna, Austria
Further Information

Publication History

Received 4 June 2009
Publication Date:
23 September 2009 (online)

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Abstract

4,5-Dihydrobenzo[g]indazoles were efficiently metallated using hindered Mg- and Zn-TMP amides. Trapping of the resulting organometallic reagents with various electrophiles furnished novel C3-substituted 4,5-dihydrobenzo[g]indazoles.

Key words

4,5-dihydrobenzo[g]indazoles - metallations - Grignard reactions - magnesium - zinc

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6

TMPMgCl˙LiCl is available from Chemetall (Frankfurt) and Aldrich.

8

i-PrMgCl˙LiCl is commercially available from Chemetall (Frankfurt).

13

The data refer to the isomeric mixture since the 1H- and 2H-benzo[g]indazoles are in equilibrium at 25 ˚C.