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Synlett 2008(18): 2846-2850  
DOI: 10.1055/s-0028-1083537
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Novel Extensions of the tert-Amino Effect: Formation of Phenanthridines and Diarene-Fused Azocines from ortho-ortho′-Functionalized Biaryls

Ágnes Polonka-Bálinta, Caterina Saracenoa, Krisztina Ludányib, Attila Bényeic, Péter Mátyus*a
a Department of Organic Chemistry, Semmelweis University, Hõgyes Endre u. 7., 1092 Budapest, Hungary
Fax: +36(1)2170851; e-Mail: peter.matyus@szerves.sote.hu;
b Department of Pharmacy, Semmelweis University, Hõgyes Endre u. 7., 1092 Budapest, Hungary
c Institute of Physical Chemistry, University of Debrecen, Egyetem tér 1., 4010 Debrecen, Hungary
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Publication History

Received 27 June 2008
Publication Date:
15 October 2008 (online)

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Abstract

Phenanthridines and azocines fused to two benzene rings or one benzene and one pyridazinone ring, which are otherwise difficult to access, were prepared via two new extensions of the tert-amino effect. The synthetic pathway includes three steps: i) Suzuki reaction of an ortho-functionalized phenylboronic acid with ortho-disubstituted benzenes or pyridazinones; ii) the Knoevenagel condensation reaction of the biaryl aldehydes formed with active methylene compounds to obtain vinyl derivatives or, through their cyclization, phenanthridines via a tert-amino effect; and iii) thermal isomerization of vinyl or phenanthridinium compounds to fused azocines via another type of tert-amino effect.

Key words

tert-amino effect - dibenzazocines - pyridazinobenzazocines - nonbonding interactions - Suzuki reaction