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Synthesis 2003(3): 0413-0425
DOI: 10.1055/s-2003-37344
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis and Reactions of 1,2,3-Triazinium Salts

Michael Mättner, Hans Neunhoeffer*
Darmstadt University of Technology, Clemens Schöpf Institute of Organic Chemistry and Biochemistry, Petersenstr. 22, 64289 Darmstadt, Germany
Fax: +49(6151)166016; e-Mail: di88@hrzpub.tu-darmstadt.de;
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Publication History

Received 22 August 2002
Publication Date:
19 February 2003 (online)

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Abstract

The synthesis of monosubstituted 1,2,3-triazinium salts 7-9 and their reactivity towards C-nucleophiles is described. The nucleophilic attack at 7-9 is regioselective at position 5, isolation of dihydroproducts was possible and an unusual ring contraction was observed.

Key words

1,2,3-triazines - cations - nucleophilic additions - π-deficient heterocycles - regioselectivity

12

Ab initio calculations done with Gaussian 94 [12] with standard basic set 6-311G*, geometries were optimized on HF/6-31G* level and characterized as minima by vibrational frequency analysis (number of imaginary frequencies = zero for minima). These provided the zero-point vibrational energies (ZPEs) which were scaled for the calculation of relative energies by an empirical factor of 0.89. [13]

15

Energies for N-2 ethylated and N-2 protonated 1,2,3-triazines 7 and 8 were defined as 0 kJmol-1