作者:Andrew S. Kende、Michel Journet
DOI:10.1016/0040-4039(95)00470-w
日期:1995.5
Acetylenic α-diazoketones, bearing gem-dimethyl substituents in the α′ position, were found to undergo an intramolecular 1,3-dipolar cycloaddition reaction in the presence of silver(I) as catalyst. In that instance, bicyclic pyrazole derivatives were isolated in 47 to 55% yield, even in the conditions of the Arndt-Eistert reaction. The requirement for gem-dimethyl substitution in acyclic substrates is rationalized
发现在银(I)作为催化剂的存在下,在α'位置带有宝石-二甲基取代基的乙炔α-二氮杂环酮发生分子内的1,3-偶极环加成反应。在这种情况下,即使在Arndt-Eistert反应条件下,也以47%至55%的收率分离出双环吡唑衍生物。根据过渡态对构象能的空间效应,合理化了无环底物中对宝石二甲基取代的要求。