Base-Mediated Reaction of the Bestmann−Ohira Reagent with Nitroalkenes for the Regioselective Synthesis of Phosphonylpyrazoles
作者:R. Muruganantham、Shaikh M. Mobin、Irishi N. N. Namboothiri
DOI:10.1021/ol070107s
日期:2007.3.1
(Bestmann-Ohira reagent), with conjugated nitroalkenes provides regioisomerically pure phosphonylpyrazoles in moderate to good yield. These pyrazoles are formed in one pot via spontaneous elimination of the nitro group. However, nitropyrazoles could be synthesized by the same strategy using alpha-bromonitroalkenes. The methodology works for the synthesis of phosphonylpyrazoles fused to other carbo-
Phosphonylpyrazoles from Bestmann−Ohira Reagent and Nitroalkenes: Synthesis and Dynamic NMR Studies
作者:Rajendran Muruganantham、Irishi Namboothiri
DOI:10.1021/jo902595e
日期:2010.4.2
also included Morita−Baylis−Hillman adducts of conjugated nitroalkenes with various electrophiles. Detailed dynamicNMRstudies were performed on the prototropic tautomerism exhibited by the phosphonylpyrazoles using CDCl3 and DMSO-d6 as solvents and 1H and 31P as the probe nuclei. These studies unraveled the existence of two tautomers in solution with a small energy difference but considerable barrier
1-重氮-2-氧代丙基膦酸二乙酯(Bestmann-Ohira试剂)作为硝基烯与环加成伙伴的应用已得到广泛研究。Bestmann-Ohira试剂与各种硝基烯烃(例如,碳环或杂环的一部分的β-取代的,α,β-二取代的和硝基乙烯)进行的碱介导反应通过室温下的一锅区域选择性反应提供了官能化的磷酸ny唑。高产。这些反应中使用的取代硝基烯烃还包括共轭硝基烯烃与各种亲电试剂的森田-贝利斯-希尔曼加合物。使用CDCl 3和DMSO- d 6作为溶剂,对膦酰基吡唑显示的质子互变异构进行了详细的动态NMR研究。1 H和31 P作为探针核。这些研究揭示了溶液中两种互变异构体的存在,它们的能量差很小,但对互变具有很大的障碍。