Oxokohlenstoffe und verwandte Verbindungen; 21. Mitteilung.<sup>1</sup>Diels-Alder Reaktion von 3-Halogeno-3-cyclobuten-1,2-dionen mit 1,1′-Bi-1-cycloalkenylen: Synthese dicycloalkano-anellierter Dihydrobenzocyclobutendione und Benzocyclobutendione
作者:Arthur H. Schmidt、Christian Künz、Marianne Malmbak、Jörg Zylla
DOI:10.1055/s-1994-25490
日期:——
Oxocarbons and Related Compounds; Part 21.1 Diels-Alder Reactions of 3-Halogeno-3-cyclobutene-1,2-diones with 1,1′-Bi-1-cycloalkenyls. Synthesis of Dicycloalkano-annulated Dihydrobenzocyclobutenediones and Benzocyclobutenediones On controlled heating to 100°C, 3-chloro-3-cyclobutene-1,2-diones (5a) reacted with 1,1′-bi-1-cyclohexenyl (6) and 1, 1′-bi-1-cyclopentenyl (13) to give the dicycloalkano-annulated dihydrobenzocyclobutenediones 7 and 16, respectively. Treatment of carbon tetrachloride solutions of 7 and 16 with bromine at reflux temperature afforded the corresponding benzocyclobutenediones 9 and 17. Surprisingly, the reaction of 5a with 1,1′-bi-1-cycloheptenyl (14) and 1,1′-bi-1-cyclooctenyl (15) gave directly the benzocyclobutenediones 20 and 21. The hitherto unknown 3-bromo-3-cyclobutene-1,2-dione (5c) was prepared by treatment of 3-hydroxy-3-cyclobutene-1,2-dione (5b) with oxalic dibromide in 76% yield. Its reaction with the dienes 6, 13, 14 has been investigated.
Multimetallic Ni- and Pd-Catalyzed Cross-Electrophile Coupling To Form Highly Substituted 1,3-Dienes
作者:Astrid M. Olivares、Daniel J. Weix
DOI:10.1021/jacs.7b13601
日期:2018.2.21
synthesis of highly substituted 1,3-dienes from the coupling of vinyl bromides with vinyl triflates is reported for the first time. The coupling is catalyzed by a combination of (5,5'-bis(trifluoromethyl)-2,2'-bipyridine)NiBr2 and (1,3-bis(diphenylphosphino)propane)PdCl2 in the presence of a zinc reductant. This method affords tetra- and penta-substituted 1,3-dienes that would otherwise be difficult
Ligand-Free Iron-Catalyzed Carbon (sp<sup>2</sup>)–Carbon (sp<sup>2</sup>) Oxidative Homo-Coupling of Alkenyllithiums
作者:Zhuliang Zhong、Zhi-Yong Wang、Shao-Fei Ni、Li Dang、Hung Kay Lee、Xiao-Shui Peng、Henry N. C. Wong
DOI:10.1021/acs.orglett.8b03893
日期:2019.2.1
and hexa-substituted 1,3-butadienes. This one-pot procedure involves lithium–iodine exchange to generate the corresponding vinyllithium intermediates. A subsequent iron-catalyzed ligand-free oxidativehomo-coupling eventually led to the formation of 1,3-butadienes in acceptable to excellent isolated yields.
bromides. The reaction proceeds efficiently when a combination of a highly substituted bromoalkene and a hydrazone derived from a ketone are employed, pointing to the convenience of a stericallyencumbered environment. This unprecedented process allows for the stereocontrolled preparation of highly substituted dienes and polyenes.
A fluoroustetraarylporphyrin has been prepared in a single reaction step starting from commercially available 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin [TPP(OH)4]. The new compound was successfully employed as a sensitizer in photooxygenationreactions carried out under homogeneous conditions, showing activity comparable to the standard 5,10,15,20-tetraphenylporphyrin (TPP) sensitizer. Photooxygenation