Synthesis 2006(9): 1513-1517  
DOI: 10.1055/s-2006-926425
PAPER
© Georg Thieme Verlag Stuttgart · New York

[4+2] Cycloaddition of Dimethyl 1,2,4,5-Tetrazine-3,6-dicarboxylate with EWG-Substituted Primary Ketene N,O-Acetals : Synthesis of Tetrafunctional Pyridazines and Pyrroles

Jörg Müller, Reinhard Troschütz*
Institut für Pharmazie und Lebensmittelchemie im Emil-Fischer-Centrum, Friedrich-Alexander-Universität, Schuhstr. 19, 91052 Erlangen, Germany
Fax: +49(9131)8522587; e-Mail: troschuetz@pharmazie.uni-erlangen.de;
Further Information

Publication History

Received 3 November 2005
Publication Date:
07 April 2006 (eFirst)

Abstract

A series of EWG-substituted primary ketene N,O-acetals were reacted with tetrazine-3,6-dicarboxylate yielding, by [4+2] cycloaddition, tetrafunctionalized pyridazines, which possess an EWG group, a primary amino function and two ester moieties. Reductive ring contraction of pyridazines gave aminopyrrole derivatives. Treatment of cyanamide with tetrazine-3,6-dicarboxylate led to a 5-amino-1,2,4-triazine derivative, which was rearranged to 4-aminoimidazole-2,5-dicarboxylic acid dimethyl ester.

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