The carbonyldicobalt-mediated alkyne/allene/CO cocyclization gives 4-alkylidenecyclopentenones as the major [2+2+1] cycloadducts. The regio- and stereoselectivities depend mainly on the substitution pattern of both the alkyne and the allenic moieties, which can be rationalized using the Magnus mechanism. However, contrary to this model, and in agreement with more recent mechanistic studies, our results
Assembly of Tetrahydroquinolines and 2-Benzazepines by Pd-Catalyzed Cycloadditions Involving the Activation of C(sp<sup>3</sup>)–H Bonds
作者:Xandro Vidal、José Luis Mascareñas、Moisés Gulías
DOI:10.1021/acs.orglett.1c01594
日期:2021.7.16
Cycloadditionreactions are among the most practical strategies to assemble cyclic products; however, they usually require the presence of reactive functional groups in the reactants. Here, we report a palladium-catalyzed formal (4 + 2) cycloaddition that involves the activation of C(sp3)–H bonds and provides a direct, unconventional entry to tetrahydroquinoline skeletons. The reaction utilizes amidotolyl
作者:Mohammed Ahmar、Jean-Jacques Barieux、Bernard Cazes、Jacques Gore
DOI:10.1016/s0040-4020(01)89984-1
日期:1987.1
palladium-catalyzed coupling reaction of allenes, vinyl or aryl halides and stabilized carbanions is described : π-allyl palladium complexes are formed by addition of a vinyl or an aryl-palladium complex to an allenic hydrocarbon and trapped by the sodium enolate of diethyl malonate giving rise with good yields to β-butadienyl or β-styryl malonates. With monoalkyi allenes, the reaction is regiospecific with attack
描述了丙烯,乙烯基或芳基卤化物和稳定化碳负离子的钯催化偶联反应:π-烯丙基钯配合物是通过将乙烯基或芳基-钯配合物添加到烯丙烃中形成的,并被丙二酸二乙酯的烯醇化钠捕获β-丁二烯基或β-苯乙烯基丙二酸酯的收率高。对于单烷基亚丙基,该反应是区域特异性的,亲核试剂攻击中间的π-烯丙基配合物的未取代的碳,并且在许多情况下具有高度立体选择性,主要形成二烯的三取代双键的E构型。使用NOE差光谱法通过1 H NMR证明了该构型。
Catalytic osmylation of allenic compounds. Synthesis of α-hydroxyketo amino acid precursors
Osmium tetroxyde-catalyzed dihydroxylation of alleniccompounds in the presence of N-Methylmorpholine Oxide leads to α-ketols. Regioselectivity of this oxidation procedure with allenic α-amino acidprecursors is greatly influenced by the nature and the remoteness of the protected aminoacid group.
Design and synthesis of polymerizable cumulated double bond system. -Living coordination polymerization of alkylallenes by π-allylnickel catalyst-
作者:Takeshi Endo、Koji Takagi、Ikuyoshi Tomita
DOI:10.1016/s0040-4020(97)00956-3
日期:1997.11
The coordination polymerization of monoalkylallenes (2a; 1,2-nonadiene, 2b; 1,2-heptadiene, 2c; cyclohexylallene, 2d; t-butylallene) was carried out by [(pi-allyl)NiOCOCF3](2) (1). The polymerization was found to proceed through a living process without any side reactions to yield soluble polymers in high yields, where the resulting polymers had predictable molecular weights and narrow molecular weight distributions. The coordination polymerization of dialkylallene (2e; 3-methyl-1,2-nonadiene, 2f; 2,3-nonadiene) was also carried out to obtain soluble polymers, although the polymerization rate of 2f was found to be considerably low compared with those of monoalkylallenes. (C) 1997 Elsevier Science Ltd.