Stepwise mechanism of formal 1, 5-sigmatropic rearrangement of dimethyl 3, 3-dialkyl-3H-pyrazole-4, 5-dicarboxylates

MW Majchrzak, E Jefferson…

文献索引：Majchrzak, Michael W.; Jefferson, Elizabeth; Warkentin, John Journal of the American Chemical Society, 1990 , vol. 112, # 6 p. 2449 - 2451

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被引用次数: 15

摘要

Compounds 1 (Scheme II) were prepared by in situ cycloaddition of the appropriate diazoalkanes to dimethyl acetylenedicarboxylate. The diazoalkanes were generated by photolysis of oxadiazolines." Pyrazoles la and lb were isolated before thermolysis in benzene at 160 OC (sealed tube) whereas IC and Id rearranged in the medium in which they were formed. Thermolysis of la afforded 2a (-83%), 3a (-9%), and several