Regioselective cyclic cotrimerization of alpha,beta-enones and alkynes by a nickel-aluminum catalyst system
Regioselective cyclic cotrimerization of alpha,beta-enones and alkynes by a nickel-aluminum catalyst system
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DOI：
10.1021/ja9704491
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发表时间：
1997-05-21
影响因子：
15
通讯作者：
Sato, Y
中科院分区：
文献类型：
--
作者：
Ikeda, S;Mori, N;Sato, Y
本文报道了一个环共聚的新例子。在镍-有机铝催化剂体系的存在下，R、β-烯酮1（1当量）和炔酮2（2当量）的反应顺利进行，生成相应的环加合物（式1中的反应a）。此外，在与1-炔的反应中还观察到区域选择性共聚反应。我们最近报道的nickel-catalyzed串联反应1,2,三甲基(TMSCl)和有机锡或organozinc提供产品相应的耦合(反应B eq 1)。1在此研究中,我们发现trimethylaluminum的反应(Me3Al) 2-cyclopenten-1-one (1) 1-hexyne(2),和TMSCl nickel-triphenylphosphine的存在(PPh3)催化剂在四氢呋喃在室温下给一个意想不到的循环cotrimerization加合物(n) 0,布鲁里溃疡),R”)H;同分异构体混合物)由1分子1a和2分子2a合成，总收率为48%（反应a）。据我们所知，还没有炔1与炔2共聚的例子。因此，我们开始研究在Me3Al存在的情况下，镍催化（5 mol%） 2a的化学计量量（即2等量比1a）的1a反应，以确定获得高产量加合物的最佳条件。钯络合物如Pd (acac) 2没有催化反应。共同化不需要TMSCl。Me3Al的含量可降至40 mol%。当苯酚（约为Me3Al的3倍）加入反应体系时，加合物的产率提高到86%。其它烯酮和炔也可用于这种共聚反应。4
We report here a new example of cyclic cotrimerization. The reaction of R, β-enones 1 (1 equiv) and alkynes 2 (2 equiv) proceeded smoothly in the presence of a nickel-organoaluminum catalyst system to give the corresponding cyclic adducts (reaction A in eq 1). Moreover, regioselective cotrimerization was observed in the reaction with 1-alkyne.We recently reported the nickel-catalyzed tandem reaction of 1, 2, chlorotrimethylsilane (TMSCl), and organotin or organozinc to provide the corresponding coupling products (reaction B in eq 1). 1 During this research, we found that the reaction of trimethylaluminum (Me3Al) with 2-cyclopenten-1-one (1a), 1-hexyne (2a), and TMSCl in the presence of a nickel-triphenylphosphine (PPh3) catalyst in THF at room temperature gave an unexpected cyclic cotrimerization adduct (n) 0, R) Bu, R′) H; isomer mixture) derived from one molecule of 1a and two molecules of 2a in a total yield of 48%(reaction A). To the best of our knowledge, there is no example of the cotrimerization of enone 1 with alkyne 2. 2 Therefore, we started to investigate the nickel-catalyzed (5 mol%) reaction of 1a with a stoichiometric amount of 2a (ie, 2 equiv vs 1a) in the presence of Me3Al to determine the optimum conditions for obtaining the adducts in high yield. A palladium complex such as Pd (acac) 2 did not catalyze the reaction. TMSCl was not required for cotrimerization. The amount of Me3Al could be reduced to 40 mol%. When phenol (ca. 3 equiv vs Me3Al) was added to the reaction system, the yield of the adduct increased to 86%. 3 Other enones and alkynes could also be applied to this cotrimerization. 4