Synthesis 2009(2): 217-226  
DOI: 10.1055/s-0028-1083291
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Diastereoselective Synthesis of Dimethyl (4R*,4a′R*,7a′R*)-1-Aryl-6′-benzoyl-4a′-methyl-5-oxo-1,4′,4a′,5,5′,6′-hexahydrospiro[pyrazole-4,7′-pyrrolo[3,4-c]pyridazine]-3′,7a′(1′Η)-dicarboxylates

Uroš Uršič, Uroš Grošelj, Anton Meden, Jurij Svete, Branko Stanovnik*
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia
Fax: +386(1)2419220; e-Mail: branko.stanovnik@fkkt.uni-lj.si;
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Publication History

Received 3 June 2008
Publication Date:
19 December 2008 (online)

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Abstract

Methyl (Z)-2-(benzoylamino)-3-(dimethylamino)propenoate (1) reacted with trimethylenemethane (2) to produce methyl (Z)-2-[benzoyl(2-methylallyl)amino]-3-(dimethylamino)propeno­ate (3), which was then converted into pyrazole derivatives 11a-h by a consecutive exchange of the dimethylamino group with hydrazine derivates 9a-h and cyclization to the ester group. Reactions of pyrazoles 11a-g with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate (6) resulted in the diastereoselective formation of 1-aryl-6′-benzoyl-4a′-methyl-5-oxo-1,4′,4a′,5,5′,6′-hexahydrospiro[pyrazole-4,7′-pyrrolo[3,4-c]pyridazine]-3′,7a′(1′H)-dicarboxylates 12a-g. This represents a simple new pathway to novel heterocyclic systems. On the other hand, when (dimethylamino)propenoate 3 reacted with aniline hydrochloride (4), followed by the cycloaddition of 1,2,4,5-tetrazine 6, dimethyl (E)- and (Z)-4-({benzoyl[1-(methoxycarbonyl)-2-(phenylamino)vinyl]amino}methyl)-4-methyl-1,4-dihydropyridazine-3,6-dicarboxylates (7) and (8) were formed, respectively.