Dérivés C-glycosyliques VIII. Synthèse de C-glycosyl-3-pyrazoles à partir d'une nitrilimine dérivée de l'anhydro-2,5-<scp>D</scp>-ribose. Compétition entre cyclo-additions dipolaires-1,3 et cyclisations non concertés
作者:J. M. J. Tronchet、Melle F. Perret
DOI:10.1002/hlca.19720550631
日期:1972.7.10
Several 3-(2,5-anhydro-ribosyl)-pyrazoles of potential medicinal interest have been synthesized by reacting alkynes or alkynylmagnesium bromides with the p-nitrophenylhydrazone of 2,5-anhydro-ribonyl bromide. From a mechanistic standpoint, it has been shown that the sugar-nitrilimine used in these studies reacts more readily as an electrophile than as a dipole. Thus, the hydrazonyl bromide gave exclusively
通过使炔烃或炔基溴化镁与2,5-脱水-核糖基溴的对硝基苯基hydr反应,已经合成了几种具有潜在医学价值的3-(2,5-脱水-核糖基)-吡唑。从机理的观点来看,已经表明,在这些研究中使用的糖-硝胺作为亲电子试剂比偶极子更容易反应。因此,当用苯基乙炔基溴化镁处理时,酰肼基溴仅给出相应的苯基乙炔基hydr,当与苯乙炔反应时,生成苯乙炔基hydr和吡唑的1:1混合物。这证明了在亚硝胺上的亲核加成比惠斯根的1,3-偶极环加成要快得多。