釕金屬錯合物與4,4-雙取代-1,6-烯炔及雙炔化合物反應之研究

Reactions of Ruthenium Cp Phosphine Complex with 4,4-Disubstituted-1,6-Enynes and Diyne

鍾佳蓓(Chia-Pei Chung)

指導教授 ： 林英智

國立臺灣大學/理學院/化學研究所/博士(2010年)

https://doi.org/10.6342/NTU.2010.03138

摘要

在本論文中，我們一開始研究九個含有末端丙炔醇以及有甲基修飾在烯基不同位置之1,6-烯炔化合物與氯配位釕金屬之三苯基磷化合物Cp(PPh3)2RuCl的化學反應。對沒有甲基取代於烯基的烯炔化合物1-3而言，其末端丙炔醇的部分與釕金屬反應後會得到釕金屬亞丙烯基錯合物6，接著再進行骨架重排而得到雙取代的釕金屬亞乙烯基錯合物7。將烯炔化合物末端丙炔醇的部份改成丙炔醚，此反應則是得到釕金屬碳烯錯化合物10為主產物，以及經由環化反應而形成的釕金屬丁二烯錯合物9為副產物。對有兩個甲基修飾在末端烯基的烯炔化合物12而言，與釕金屬的反應會因為選用的溶劑不同，而得到在一號碳位置有環戊烯取代的釕金屬碳烯錯化合物15及16或是得到釕金屬亞乙烯基錯合物17。我們假設錯化合物15和16的形成是經由末端炔基的三鍵π-配位在釕金屬的中間體，於二號碳位置進行碳碳鍵生成的環化反應而得。然而，若是中間體以釕金屬亞乙烯基錯合物形式呈現，此反應則會經由進行脫水反應形成釕金屬亞丙烯基錯合物後，再更進一步進行脫去雙甲基取代丙烯基的烯反應而得到17。對末端烯基的內部碳上修飾甲基的烯炔化合物21和22而言，與釕金屬反應則是可以得到在二號碳位置上鍵結著五環的釕金屬亞乙烯基錯合物23和24。我們推測此結果是經由釕金屬亞丙烯基形式的中間體在三號碳上進行環化反應而得。以上反應大都取決於陽離子中間體的穩定性來決定反映的方向。
另一方面，我們延伸1,6-烯炔化合物至1,6-雙炔化合物。利用四種含有末端丙炔醇和以三甲基矽保護的末端炔相連結的1,6-雙炔化合物與氯配位釕金屬之三苯基磷化合物,[Ru]-Cl ([Ru] = Cp(PPh3)2Ru),會生成兩種不同形式的錯合物。在第一種形式中，雙炔化合物只以末端丙炔醇部分與釕金屬反應而形成釕金屬亞乙烯基錯合物，釕金屬亞丙烯基錯合物，與釕金屬炔基錯合物。而第二種形式是經由1,6-雙炔化合物的兩個三鍵官能基進行碳碳鍵生成反應而得到釕金屬丙烯基碳烯錯合物。雙炔化合物30與含氯取代的釕金屬錯合物反應可同時獲得兩種形式的產物，釕金屬亞乙烯基錯合物36與釕金屬丙烯基碳烯錯合物35。形成錯合物35的反應包含了兩個炔基同時配位在金屬上進行環化反應同時伴隨著三苯基磷的遷移至1,6-雙炔配位基的一號位置碳上。利用鹽酸與五個電子配位的釕金屬丙烯基碳烯錯合物35反應可以得到含有四個電子配位的1,3-雙烯基與氯配位的金屬錯合物38。化合物31與氯配位釕金屬之三苯基磷化合物反應只會得到第一種形式的混合產物，分別為釕金屬亞丙烯基錯合物39與磷基加成之釕金屬炔基錯合物40，後者為一個三苯基磷加成在釕金屬亞丙烯基錯合物的三號碳位置上。同樣的反應加入過量的三苯基磷就可以得到單一錯合物40。然而，引入一個甲基官能基於1,6-雙炔三號碳位置的化合物32與氯配位釕金屬之三苯基磷化合物反應，會得到同樣有磷基加成在配位基上的釕金屬丙烯基碳烯錯合物41。在31和32兩種化合物的反應中可以觀察到炔基對三苯基磷有很強的結合力，使得碳磷鍵的生成有不同的位向選擇性。含有正丁基取代在丙烯醇的雙炔化合物33與釕金屬錯合物反應，可以同時獲得釕金屬亞丙烯基錯合物43與釕金屬丙烯基碳烯錯合物44。
另外我們也研究了三種含有末端丙炔醇以及有甲基修飾在烯基位置之1,6-烯炔化合物，1、3和12，與氯配位釕金屬之三苯基磷化合物Cp(PPh3)2RuCl及氯配位釕金屬之一，二-雙苯基磷乙烷化合物Cp(dppe)RuCl的化學反應。在這部分我們將注意力放在相同的1,6-烯炔化合物與配位不同磷基的釕金屬之反應性。對有兩個甲基修飾在末端烯基的烯炔化合物12而言，與Cp(PPh3)2RuCl和Cp(dppe)RuCl反應分別會得到釕金屬亞乙烯基錯合物5g和5g’。分別將5g和5g’去質子化則可得到中性釕金屬炔基錯合物46和46’。釕金屬錯合物46和46’於空氣中可與氧分子進行[2+2+2]反應而得到釕金屬醯基錯合物47和47’。尤其是錯合物46’，即使在黑暗中與氧氣反應行程47’可將時間縮短於10分鐘內完成。然而，若將1,6-烯炔化合物的丙烯基部份由雙甲基取代改成沒有甲基修飾的丙烯基，或者將氧氣換成其它有活性的碳碳雙鍵試劑，類似的化學變化並不會發生。將釕金屬炔基錯合物46e置於零度下乙醚與水的混何溶劑中與氟硼酸反應，可以得到質子化的釕金屬亞乙烯基錯合物5e。然而將錯合物46’、46e’和46h’進行相同的程序，並不會得到釕金屬亞乙烯基錯合物的產物，令人訝異的是，反而得到釕金屬烴基碳烯錯合物48’、48e’和48h’。我們假設這類反應是因為一，二-雙苯基磷乙烷的立體障礙較小，使得釕金屬炔基化合物的一號碳位置在酸性環境下容易與水分子反應而造成。
以上的化學反應機制及釕金屬錯合物結構，可藉由氘取代實驗、二維核磁共振光譜儀及X光單晶繞射分析儀來作確認及鑑定。

關鍵字

烯炔化合物 ； 釕金屬 ； 亞乙稀基 ； 亞丙烯基 ； 環化反應 ； 丙烯基碳烯 ； 乙炔基 ； 醯基 ； 氧化加成

並列摘要

We studied chemical reactions of Cp(PPh3)2RuCl with nine 1,6-enyne compounds (1-4, 8, 12, 19, 21, and 22) in which the triple bond is associated with propargylic alcohol and the olefinic group has various substituted methyl groups. For the enyne compounds 1-3 with no substituted methyl group, the reaction takes place at the propargylic alcohol first giving the allenylidene complex 6 which could undergo a skeletal rearrangement to yield the disubstituted vinylidene complex 7. By changing the propargylic alcohol to propargylic ether, the reaction gives the carbene complex 10 as the major product and the butadiene complex 9 by a cyclization reaction as the minor product. For the enyne 12 with two methyl groups at the terminal carbon of the olefinic part, formation of either of the carbene complexes 15 and 16 with a substituted cyclopentenyl ring at Cα or the vinylidene complex 17 is controlled by the use of solvent. For the formation of 15 and 16, a C-C bond-forming cyclization reaction is proposed to occur at Cβ in an intermediate where the triple bond is π-coordinated. However, for the vinylidene intermediate, the reaction may proceed by the formation of the allenylidene, which undergoes a retro-ene reaction to bring about cleavage of the dimethyl substituted allyl group giving 17. For two enynes 21 and 22 where each olefinic portion is internally substituted with one methyl group, two vinylidene complexes 23 and 24 each with a five-membered ring bonded at Cβ are isolated. The reaction proceeds via formation of an allenylidene intermediate followed by a cyclization at Cγ. Stabilization of the cationic charge by the presence of methyl subsituents clearly controls the reaction pathway to give different products.
On the other hand, reactions of the four 1,6-diynes 30 and 31−33, each with one terminal propargylic alcohol and one internal triple bond containing Me3Si groups, with [Ru]Cl ([Ru] = Cp(PPh3)2Ru) led to two types of products. In the first type, only the propargylic group is involved in the reaction leading to vinylidene, allenylidene, or acetylide complexes. A C−C bond formation of two triple bonds in 1,6-diynes gave allylcarbene products of the second type. The reaction of diyne 30 with [Ru]Cl gave both types of complexes, namely the vinylidene complex 36 and the allylcarbene complex 35. The formation of 35 proceeds by a cyclization reaction involving two triple bonds on the metal accompanied by a migration of a phosphine ligand to Cα. Addition of HCl to 35 transforms the five-electron-donor allylcarbene ligand to the four-electron-donor diene ligand along with formation of a Ru−Cl bond, giving complex 38. The reaction of 31 with [Ru]Cl yielded only the first type, giving a mixture of two cationic complexes, the allenylidene complex 39 and the phosphonium acetylide complex 40, the latter resulting from further addition of a phosphine molecule to Cγ of 39. The same reaction in the presence of excess phosphine gave 40 only. However, with an additional methyl group, the 1,6-diyne 32 reacted with [Ru]Cl to give the allylcarbene complex 41 also with a phosphonium group on the ligand. In both reactions of 31 and 32, strong affinity between alkyne and phosphine was observed, resulting in formations of P−C bonds with different regioselectivity. From the reaction of [Ru]Cl with diyne 33 containing a tert-butyl group at the propargylic carbon, both the allenylidene complex 43 and the allylcarbene complex 44 were obtained.
We also studied chemical reactions of Cp(PPh3)2RuCl and Cp(dppe)RuCl with three 1,6-enyne compounds (1, 3 and 12) in which the triple bond is associated with propargylic alcohol and the olefinic group has substituted methyl groups. Herein, we focus our attentions on the influence of substituents, PPh3 and dppe, mediated on the ruthenium center with the same 1,6-propargyl enynes. The vinylidene complexes 5g and 5g', tethering a dimethyl allyl moiety at C4 were prepared from the reaction of the 4,4-diphenylsubstituted propargylic alcohol 12 with Cp(PPh3)2RuCl and Cp(dppe)Cl in moderate to high yield, respectively. Deprotonation of 5g and 5g' yields the acetylide complexes 46 and 46', respectively. When 46 and 46’ were exposed to atmospheric condition, molecular oxygen readily reacts possibly via a [2+2+2] cyclization with the 1,6-enyne ligand of complexes 46 and 46’ to yield the acyl complexes 47 and 47’. Especially, the reaction of oxygen with the 1,6-enyne ligand in 46’ is achieved under mild condition in less than 10 min even in dark. When changed the dimethyl allyl moiety to allyl moiety or replaced O2 by other reactants containing activated C=C double bonds, this transformation would not occur. Treatment of the acetylide complex 46e with HBF4 in ether/H2O at 0 oC generated vinylidene complex 5e. However, treatment of the acetylide complexes 46’, 46e’ and 46h’ with the same procedure generated no vinylidene complex, but surprisingly, the corresponding ruthenium hydroxycarbene complexes 48’, 48e’ and 48h’ were obtained. It is suggested that the steric effect of the coordinated dppe ligand is significant in exposing the acetylide Cα atom to be attacked by a water molecule in acidic environment. These chemical reactions and their mechanisms are corroborated by structure determinations of ruthenium complexes using deuterium labeling experiments, 2D-NMR and single crystal X-ray diffraction analysis.

並列關鍵字

Enyne ； ruthenium ； vinylidene ； allenylidene ； cyclization ； allylcarbene ； phosphonium acetylide ； acetylide ； acyl ； oxidative addition

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