Ogoshi Sensuke, Tonomori Kei-ichi, Oka Masa-aki, Kurosawa Hideo
Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
J Am Chem Soc. 2006 May 31;128(21):7077-86. doi: 10.1021/ja060580l.
The reversible oxidative cyclization of dienes and aldehydes with nickel(0) proceeded to give eta(3):eta(1)-allylalkoxynickel complexes. The treatment of these complexes with carbon monoxide led to the formation of the corresponding lactone and/or the regeneration of a butadiene and an aldehyde concomitant with the formation of Ni(CO)(3)(PCy(3)). The scission of the nickel-oxygen bond of the allylalkoxy complexes with ZnMe(2) leading to eta(3)-allyl(methyl)nickel was very efficient to suppress the reverse reaction of the oxidative cyclization. The methylated eta(3)-allylnickel compound underwent the reductive elimination. The carbonylative coupling reaction of the eta(3)-allyl(methyl)nickel proceeded as well under a carbon monoxide atmosphere. Similarly, the addition of Me(3)SiCl to eta(3):eta(1)-allylalkoxynickel complexes was also efficient for the inhibition of the reverse reaction. The resulting eta(3)-1-siloxyethylallylnickel complex was treated with carbon monoxides followed by the addition of MeOH to give the expected hydroxyester. This method is efficient as well even for the eta(3):eta(1)-allyl(alkoxy)nickel complex containing acetone as a component, which was so prone to undergo the reverse reaction hampering its isolation. The isolation of the eta(3):eta(1)-allylalkoxynickel complex containing ketone as a component was made easier by the use of heavier butadiene and ketone, such as 2,3-dibenzyl-1,3-butadiene and benzophenone or by the use of cyclobutanone. The reaction with styrene oxide gave the eta(3):eta(1)-allylalkoxynickel containing phenylacetoaldehyde, an isomer of styrene oxide.
二烯烃与醛类在零价镍作用下进行的可逆氧化环化反应生成了η(3):η(1)-烯丙基烷氧基镍配合物。用一氧化碳处理这些配合物会导致相应内酯的形成和/或丁二烯与醛的再生，同时生成Ni(CO)₃(PCy₃)。烯丙基烷氧基配合物的镍-氧键与ZnMe₂发生断裂生成η(3)-烯丙基(甲基)镍，这对于抑制氧化环化的逆反应非常有效。甲基化的η(3)-烯丙基镍化合物会发生还原消除反应。η(3)-烯丙基(甲基)镍的羰基化偶联反应在一氧化碳气氛下也能进行。同样，向η(3):η(1)-烯丙基烷氧基镍配合物中加入Me₃SiCl对抑制逆反应也很有效。将所得的η(3)-1-硅氧基乙基烯丙基镍配合物用一氧化碳处理，然后加入MeOH得到预期的羟基酯。该方法对于含有丙酮作为组分的η(3):η(1)-烯丙基(烷氧基)镍配合物同样有效，因为该配合物极易发生逆反应，阻碍其分离。通过使用较重的丁二烯和酮，如2,3-二苄基-1,3-丁二烯和二苯甲酮，或者使用环丁酮，使得分离含有酮作为组分的η(3):η(1)-烯丙基烷氧基镍配合物变得更容易。与环氧苯乙烷反应生成了含有苯乙酮醛（环氧苯乙烷的一种异构体）的η(3):η(1)-烯丙基烷氧基镍。
