Insect sex pheromones: Palladium-catalyzed synthesis of aliphatic 1,3-enynes by reaction of 1-alkynes with alkenyl halides under phase transfer conditions
作者:Renzo Rossi、Adriano Carpita、Maria G. Quirici、Maria L. Gaudenzi
DOI:10.1016/0040-4020(82)80204-4
日期:1982.1
prepared in good yields by coupling reaction of 1-alkynes or ω-functionalized 1-alkynes halides in the presence of a catalytic amount of (PPh3)4Pd and Cul. The reactions, which were carried out underphasetransferconditions employing benzyltriethylammonium chloride as phasetransfer agent, benzene as organic solvent and diluted aq NaOH as base, occurred with 100% stereospecificity when 1-halo-1-alkenes
Enantioselective total synthesis and correction of the absolute configuration of megislactone
作者:Guo-Bao Ren、Yikang Wu
DOI:10.1016/j.tet.2008.02.054
日期:2008.5
the trans isomer of the remote double bond in a long alkyl chain was clearly revealed in 1H and 13C NMR in the presence of a lactone ring. The present work unambiguously shows that the absolute configuration of the natural compound is the antipode of the one originally reported. Some errors in the previous 1H and 13C NMR signal assignments are also corrected.
以对映纯的形式合成了标题化合物,它是来自大叶鸢尾的成分之一。C-2和C-3的立体异构中心是通过使用手性辅助剂诱导的不对称醛醇缩合而构建的,而C-4是从相应的旋光性乳酸中衍生而来的。侧链中的碳-碳双键源自纯顺式使用Suzuki偶合与碘化乙烯基碘,其中烷基硼烷是由相应的末端烯烃原位形成的。在用CAN对TBS基团进行脱保护的过程中,观察到了长链中孤立的C-C双键的先前未知的(部分)顺式至反式转化。出乎意料的是,在内酯环存在下的1 H和13 C NMR中清楚地揭示了长烷基链中远端双键的反式异构体原本无法检测到的共存现象。本工作明确地表明,天然化合物的绝对构型是最初报道的一种的对映体。以前的1 H和13 C NMR信号分配中的某些错误也已得到纠正。
Copper-Catalyzed C−P Bond Construction via Direct Coupling of Secondary Phosphines and Phosphites with Aryl and Vinyl Halides
作者:Dmitri Gelman、Lei Jiang、Stephen L. Buchwald
DOI:10.1021/ol0346640
日期:2003.6.1
halides with diaryl and dialkyl phosphines, as well as with dibutyl phosphite, is reported. This highly efficient transformation is realized through the use of copper(I) iodide as a catalyst, N,N'-dimethylethylenediamine as a ligand, and Cs(2)CO(3) as a base. A variety of sterically hindered and/or functionalized substrates were found to react under these reactionconditions to provide products in good
mainly from the halo-λ3-iodane intermediate; the substitution occurs as a bimolecular reaction with the external halideion while the elimination is a unimolecular (intramolecular) reaction. The intermediacy of the hypervalent λ3-iodane as well as of the iodate are also confirmed by UV spectroscopy. The secondary kinetic isotope effects, leaving group substituenteffects, and pressure effects on the
Pd-catalyzed Highly Regio- and Stereocontrolled Direct Alkenylation of Electron-deficient Polyfluoroarenes
作者:Fei Chen、Xingang Zhang
DOI:10.1246/cl.2011.978
日期:2011.9.5
An effective and reliable method for Pd-catalyzed highly regio- and stereocontrolled direct alkenylation of electron-deficientpolyfluoroarenes with alkenyl iodides has been developed. The advantages of this reaction are its high regio- and stereoselectivity, mild reaction temperature (70 degrees C), and the use of readily available Pd(PPh(3))(4). This approach provides a useful access to polyfluoroarylated