Trimethylsilyl Trifluoromethanesulfonate-Promoted Cyclocondensation of β-Ketoenamides and Subsequent Nonaflation to Pyrid-2-yl and Pyrid-4-yl Nonaflates as Flexible Precursors for Polysubstituted Pyridines
作者:Hans-Ulrich Reissig、Paul Hommes、Sarah Berlin
DOI:10.1055/s-0033-1338548
日期:——
Dedicated to Professor Ernst Schaumann on the occasion of his70thbirthday Abstract The intramolecular condensation of β-ketoenamides to 2- and/or 4-pyridone derivatives using either KOt-Bu or trimethylsilyl trifluoromethanesulfonate/Hünig’s base was investigated. Subsequent nonaflation of the cyclization products allowed a facile purification and further functionalization through Suzuki–Miyaura couplings
献给恩斯特·绍曼(Ernst Schaumann)教授70岁生日之际 抽象 研究了使用KO t -Bu或三甲基甲硅烷基三氟甲磺酸盐/Hünig碱将β-酮烯酰胺分子内缩合为2-和/或4-吡啶酮衍生物。随后环化产物不被烧蚀,可以通过Suzuki-Miyaura偶联剂轻松纯化并进一步官能化,从而产生新的高度取代的吡啶衍生物。讨论了环缩合的区域选择性对β-酮烯酰胺结构的依赖性。 研究了使用KO t -Bu或三甲基甲硅烷基三氟甲磺酸盐/Hünig碱将β-酮烯酰胺分子内缩合为2-和/或4-吡啶酮衍生物。随后环化产物不被烧蚀,可以通过Suzuki-Miyaura偶联剂轻松纯化并进一步官能化,从而产生新的高度取代的吡啶衍生物。讨论了环缩合的区域选择性对β-酮烯酰胺结构的依赖性。
Generation of Dimethyl Sulfoxide Coordinated Thermally Stable Halogen Cation Pools for C−H Halogenation
作者:Pallaba Ganjan Dalai、Kuntal Palit、Niranjan Panda
DOI:10.1002/adsc.202101291
日期:2022.3
A method to generate halogen cation pools from the reaction of 1,2-dihaloethanes (hal=Br, I) and dimethyl sulfoxide (DMSO) for C−H halogenation of arenes and heteroarenes was reported. The initial reaction of DMSO and 1,2-dihaloethane generates the sulfur ylide, which undergoes pyrolytic elimination of ethylene by affording halonium ions. These ions were accumulated and stabilized by DMSO through coordination
Valuable chiral building blocks were synthesized with excellent enantioselectivity and diastereoselectivity through tandem hydrogenation of (Z)‐β‐ketoenamides, which were in turn prepared by the direct condensation of 1,3‐diketones with acetamide (see scheme). The chiral amino alcohol products can be converted into useful γ‐aryl isobutylamines through hydrogenolysis with Pd/C. R1=aryl, heteroaryl,
A series of opticallypure β-amino ketones have been synthesized in high enantioselectivities (ee > 99%) by Rh-DuanPhos-catalyzed asymmetric hydrogenation of readily prepared β-keto enamides. Further reduction of these β-amino ketones with hydrogen and Pd/C leads to the formation of a variety of protected enantiomerically pure γ-aryl amines (ee > 99%), which are key building blocks in many bioactive
cyclization of N-acetyl enamines and intermolecular cyclocondensation of enamines and nitriles was investigated. The reaction was performed under mild conditions and gave oxazoles and imidazoles, respectively, in moderate to excellent yields. This transformation exhibits good reactivity, selectivity and functional group tolerance. The selectivity of the intra- or intermolecular reaction is dependent on the