Annulation of β-aryl-α-nitro-α,β-enals and 2,2-dimethyl-1,3-dioxan-5-one: a one-step assembly of nitrocyclitols. Application to a short practical synthesis of (±)-7-deoxy-2-epi-pancratistatin tetraacetate
Annulation of β-aryl-α-nitro-α,β-enals and 2,2-dimethyl-1,3-dioxan-5-one: a one-step assembly of nitrocyclitols. Application to a short practical synthesis of (±)-7-deoxy-2-epi-pancratistatin tetraacetate
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。
Synthesis of highly diversified 1,2,3-triazole derivatives via domino [3 + 2] azide cycloaddition and denitration reaction sequence
In this paper, an elegant synthesis of 1,2,3-triazole derivatives via domino [3 + 2] azide cycloaddition and denitration reaction sequence under catalyst free conditions has been described. Treatment of Baylis–Hillmanadducts and their cyclic derivatives from nitroolefins with sodium azide in the absence of catalyst smoothly afforded the 1,2,3-triazole derivatives in excellent yields.
Annulation of β-aryl-α-nitro-α,β-enals and 2,2-dimethyl-1,3-dioxan-5-one: a one-step assembly of nitrocyclitols. Application to a short practical synthesis of (±)-7-deoxy-2-epi-pancratistatin tetraacetate
作者:Juan Carlos Ortiz、Lidia Ozores、Fernando Cagide-Fagín、Ricardo Alonso
DOI:10.1039/b606277f
日期:——
A novel, highly stereocontrolled formal [3 + 3] annulation of β-aryl-α-nitro-α,β-enals with the enamine derived from 2,2-dimethyl-1,3-dioxan-5-one and pyrrolidine afforded protected nitrocyclitols with five newly created stereocentres and constituted the key step in a short, gram-scale synthesis of a pancratistatin analogue.