Carbostannylation of alkynes catalyzed by an iminophosphine-palladium complex
Carbostannylation of alkynes catalyzed by an iminophosphine-palladium complex
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DOI：
10.1021/ja974206k
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发表时间：
1998-04-01
影响因子：
15
通讯作者：
Hiyama, T
中科院分区：
文献类型：
--
作者：
Shirakawa, E;Yoshida, H;Hiyama, T
炔的碳化产生顺式取代的烯基金属，并且是立体选择性烯烃合成的最有用的反应之一，因为所得的烯基金属可以进一步转化为各种取代的乙烯。特别是碳铜化、2锆催化碳铝化3和镍催化碳锌化4由于其广泛的适用性而具有很高的合成潜力。尽管烯基锡烷是各种烯属目标的有用合成前体，但尚未发表有关过渡金属催化的炔碳锡烷基化的报告。6-8在这里，我们报告了钯催化的碳锡烷基化的炔使用炔基锡烷。我们已经报道了三丁基（苯乙炔基）锡（2a）与N-（2-（二苯基膦基）亚苄基）-2-苯乙胺（1）配位的钯（0）配合物氧化加成，所得氧化加成物（3）参与钯催化的2a与芳基碘偶联的催化循环（方案1）。9我们设想钯配合物3应该与炔反应得到锡羰基化产物。用[PdCl（π-C3 H5）] 2-1（5mol%Pd）的1：2混合物在乙炔气氛（1atm）下在THF中于50 ℃处理2a 2小时，通过排他的合成加成以81%的收率11得到作为单一异构体的三丁基[（Z）-2-（苯乙炔基）乙烯基]锡（5a）10（方案2）。使用三苯基膦（2当量于钯）代替1在延长的时间内（43小时）仅得到48%的5a产率。Pd（0）-1，3-双（二苯基膦基）丙烷
Carbometalation of alkynes generates cis-substituted alkenylmetals and is one of the most useful reactions for stereoselective olefin synthesis, since the resulting alkenylmetals can be transformed further to variously substituted ethylenes. 1 In particular, carbocupration, 2 zirconium-catalyzed carboalumination3 and nickelcatalyzed carbozincation4 have high synthetic potential due to wide applicability. Although alkenylstannanes are useful synthetic precursors for various olefinic targets, 5 no report has been published on the transition-metal-catalyzed carbostannylation of alkynes. 6-8 Here, we report the palladium-catalyzed carbostannylation of alkynes using alkynylstannanes. We have already reported that tributyl (phenylethynyl) tin (2a) adds oxidatively to a palladium (0) complex coordinated by N-(2-(diphenylphosphino) benzylidene)-2-phenylethylamine (1) and that the resulting oxidative adduct (3) is involved in the catalytic cycle of the palladium-catalyzed coupling of 2a with aryl iodides (Scheme 1). 9 We envisaged that palladium complex 3 should react with alkynes to give carbostannylation products. This turned out to be the case.Treatment of 2a with a 1: 2 mixture of [PdCl (π-C3H5)] 2-1 (5 mol% of Pd) under an acetylene atmosphere (1 atm) in THF at 50 C for 2 h gave tributyl [(Z)-2-(phenylethynyl) ethenyl] tin (5a) 10 in 81% yield11 as a single isomer through an exclusive synaddition (Scheme 2). The use of triphenylphosphine (2 equiv to palladium) in place of 1 gave only 48% yield of 5a in a prolonged period (43 h). A Pd (0)-1, 3-bis (diphenylphosphino) propane