Fumaric acid pyrazoline

In addition to the reactions mentioned, ethyl diazoacetate takes part in many condensations with acetylene and ethylene derivatives, when the nitrogen is retained in the molecule. Thus, with esters of fumaric acid, for example, pyrazoline tricarboxylic esters are produced ... 

The formation of spirocyclopropanes from the reaction of diazodiphenylmethane and ( )-8-phenylmenthyl esters of acrylic acid and methyl fumarate occurred with a modest level of diastereofacial selectivity (136). In contrast, diastereoselectivities of 90 10 were achieved in the cycloadditions of diazo(trimethylsilyl)methane with acrylamides 65 derived from camphor sultam as the chiral auxiliary (137) (Scheme 8.16). Interestingly, the initial cycloadducts 66 afforded the nonconjugated A -pyrazolines 67 on protodesilylation the latter were converted into optically active azaproline derivatives 68. In a related manner, acrylamide 69 was converted into A -pyrazolines 70a,b (138). The major diastereoisomer 70a was used to synthesize indolizidine 71. The key step in this synthesis involves the hydrogenolytic cleavage of the pyrazoline ring. 

In the historical introduction to this volume (Sect. 1.1), it was mentioned that Buchner studied reactions of ethyl diazoacetate with ethenedicarboxylic acid in 1888. In the following year, he discovered pyrazole, obtained from methyl diazoacetate and dimethyl acetylenedicarboxylate followed by thermolysis. Finally, in 1893 Buchner et al. synthesized 4,5-dihydro-l//-pyrazole (2-pyrazoline) from methyl diazoacetate and methyl acrylate. Von Pechmann, the discoverer of diazomethane, performed analogous reactions of fumarates and maleates (von Pechmann, 1894, von Pechmann and Burkard, 1890). ... 

The reaction of diazomethane with dimethyl fumarate was reported by Von Pechmann to give the diester of 2-pyrazoline-4,5-dicarboxylic acid 25 (21,26) product was isolated as the acid after hydrolysis. 

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