Selective C–C Bond Activation of 2-Aryl-1-methylenecyclopropanes Promoted by Ir(I) and Rh(I) Hydrido Complexes. Mechanism of Ring-Opening Isomerization of the Strained Molecules
摘要:
[IrH(CO)(PPh3)3] 可促进 2-苯基-1-亚甲基环丙烷在室温下开环,生成带有 2-苯基-3-丁烯基螯合配体的 Ir 复合物 [Ir{η2-CH2CH(Ph)CH=CH2-κC1}(CO)(PPh3)2] (1)。过量的 2-苯基-1-亚甲基环丙烷与[IrH(CO)(PPh3)3]在 50 °C下反应生成[Ir{η2-(o-C6H4)CH(Me)CH=CH2-κC1}(CO)(PPh3)2](2),同时生成 1-苯基-1,3-丁二烯和 2-苯基-1,3-丁二烯。2,2-二苯基-1-亚甲基环丙烷与[IrH(CO)(PPh3)3]反应,在 50 °C 时生成[Ir{η2-CH2CPh2CH=CH2-κC1}(CO)(PPh3)2](3),在 100 °C 时生成[Ir{η2-(o-C6H4)CMe(Ph)CH=CH2-κC1}(CO)(PPh3)2](4)。在 100 °C 下加热 3 的溶液也能定量生成 4。3 的 X 射线晶体学显示,围绕与 2,2-二苯基-3-丁烯基螯合配体成键的 Ir 中心,存在五配位结构。室温下,2,2-二苯基-1-亚甲基环丙烷和 2,2-二(4-氟苯基)-1-亚甲基环丙烷与[RhH(CO)(PPh3)3]反应生成[Rh{η2-CH2CAr2CH=CH2-κC1}(CO)(PPh3)2](5a:Ar = Ph,5b:Ar = C6H4-F-4)。在 50 °C下反应会导致底物开环和苯基正金属化,分别生成[Rh{η2-(o-C6H4)CMe(Ph)CH=CH2-κC1}(CO)(PPh3)2](6a)和[Rh{η2-(o-C6H3-F-4)CMe(C6H4-F-4)CH=CH2-κC1}(CO)(PPh3)2](6b)。在反应过程中观察到 1,1-二芳基-1,3-丁二烯的形成。在 50 °C下加热 5a 的溶液会生成 1,1-二苯基-1,3-丁二烯和烯丙基铑络合物 8,而不是 6a,不过在 50 °C下将过量的 2,2-二苯基-1-亚甲基环丙烷与 5a 反应会生成 60%的 6a。根据产物和反应速率对上述反应的机理进行了讨论。P(OMe)3 与 5a 的 Rh 中心配位,导致 CO 配体插入 Rh-C 键,生成 [Rh{η2-CO-CH2CPh2CH=CH2-κC1}(P(OMe)3)3] (7)。
Ruthenium-Catalyzed Hydroarylation of Methylenecyclopropanes through CH Bond Cleavage: Scope and Mechanism
作者:Lutz Ackermann、Sergei I. Kozhushkov、Dmitry S. Yufit
DOI:10.1002/chem.201200406
日期:2012.9.17
2‐diphenylmethylenecyclopropane (2), methylenespiropentane (3), bicyclopropylidene (4), (dicyclopropylmethylene)cyclopropane (5), and benzhydrylidenecyclopropane (6) through CH bond functionalization of 2‐phenylpyridine (7 a) and other arenes with directing groups were studied. The reaction was very sensitive to the substitution on the methylenecyclopropanes. Although these transformations involved (cyclopropylcarbinyl)–metal
We report here a C–H homoallylation reaction of aromaticketones with methylenecyclopropanes (MCPs) only using a catalytic amount of Fe(PMe3)4. A variety of aromaticketones and MCPs are applicable to the reaction to form ortho-homoallylated aromaticketones selectively via regioselective scission of the three-membered rings. The homoallylated products are amenable to further elaborations, providing
The first example of a hypervalent iodine(III)‐mediated oxidativefluorination of alkylsilanes by fluorideions without the use of transition metals is demonstrated. This reaction is operationally simple, scalable, and proceeds under mild reaction conditions. Mechanistic studies suggest the involvement of a single‐electron transfer resulting from the interaction of an organopentafluorosilicate and
Organic photochemistry. 77. Simultaneous capture of two distinct radical-ion intermediates generated from the EDA complexes of three-membered compounds with TCNE by photoexcitation and in the dark
作者:Tsutomu Miyashi、Masaki Kamata、Toshio Mukai
DOI:10.1021/ja00243a035
日期:1987.4
Irradiation of the electrondonor-acceptor (EDA) complexes of 2,2-diaryl-1-methylenecyclopropanes, 1,1,2,2-tetraarylcyclopropanes, 2,3-diaryloxiranes, or 2,3-diarylaziridines with tetracyanoethylene (TCNE) under aerated conditions involved oxygenation and/or the (3 + 2) cycloaddition with TCNE. The same oxygenation took place in the dark when the EDA complexes of 2,2-diaryl-1-methylenecyclopropanes
The reaction of 2,2-diphenylmethylenecyclopropane (5) with an excess of lithium and a catalytic amount of DTBB (4 mol %) in THF at −78 °C leads to the formation of dilithiated species 6–8 by reductive opening of the cyclopropane ring. Further reaction of these intermediates with different electrophiles [E = H2O, D2O, CH2CMeCH2Cl, Me3SiCl, Me3SiCH2Cl, t-BuCHO, Me2CO, Et2CO, n-Pr2CO, i-Pr2CO, t-Bu2CO