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  • 學位論文

釕金屬錯合物與末端芳香炔烴及2-乙炔苯基乙烯基醚之反應研究

Reactions of Ruthenium Complexes with Terminal Aryl Alknyes and 2-Ethynylphenyl Vinyl Ethers

指導教授 : 林英智

摘要


有別於以往本實驗室較常利用其具有環戊二烯基之配位基的釕金屬錯化合物(CpRu(PPh3)2Cl),我們嘗試使用以戊二烯基為配位基之釕金屬錯化合物(C5H7Ru(PPh3)2Cl)當作催化試劑1,並搭配末端芳香基炔類2為起始物,在氮氣及室溫下,可以成功進行偶聚反應得到具有不同位向選擇性的含烯炔官能基之有機物3和4,其中以順式之產物為主要產物,產率有中等以上的表現60-70%,然而使用具有不同取代基之芳香基為取代基時,發現當芳香基上面具有鄰位取代基時,其產率的表現不甚理想,推測是在形成配位之中間體時,鄰位官能基之立體障礙,造成反應性下降,在反應溶劑的優化時,發現當溶劑為含氮異原子之溶劑,其反應效果不佳,推測是含氮之溶劑其配位性較含氧原子之溶劑強,一旦配位上釕金屬時,造成炔類無空間可進入配位中心,導致反應無法進行。接著,我們將同一反應的反應性質由催化反應提升其劑量為當量反應時,則反應進行三聚反應而產生磷鹽6,其產率亦有中等的效果59-67%,很幸運的是我們有得到磷鹽6的晶體。以不同取代基之炔類為起始物,亦可經由此反應條件而得到不同取代基的磷鹽。 第二個研究中,針對本實驗室較常利用環戊二烯基釕金屬錯化合物(CpRu(PPh3)2Cl),搭配2-乙炔苯基乙烯基醚7為起始物進行反應探討,發現當溶劑為醇類時,進行催化合環反應,而得到含氧原子之七環有機物8,並且隨著醇類不同,或修飾乙烯基上不同位置之甲基,也可以得到相對應的七環有機物。然而當溶劑由醇類改為二氯甲烷時,則催化反應不再發生,取而代之的是以當量而進行的骨架重排反應,我們發現當乙烯基上沒有甲基取代時,會斷裂原本炔基上的碳-碳參鍵,而進行重排反應,形成亞乙烯基釕金屬錯合物9a,其中經由核磁共振光譜分析,得知氫譜的偶合常數,其具有反式的雙鍵性質,對於亞乙烯基釕金屬錯合物9a的相關反應性質也一併探討,倘若乙烯基上的末端碳具有一個甲基取代時,則會斷裂乙烯基的碳-碳雙鍵與乙烯氧基的碳-氧單鍵,而進行骨架重排反應,形成釕金屬碳烯錯化合物14b,也成功地得到其晶體結構。我們也發現當乙烯基上末端碳修飾兩個甲基時,則重排反應不進行,只會形成簡單的亞乙烯基釕金屬錯合物,推測是因為對於氧原子呈現反式構型的甲基會抑制重排反應的發生,然而當乙烯基上內部碳修飾一個甲基時,則會先進行水解反應,再進行環化反應,而得到含氧原子的雙取代釕金屬碳烯錯化合物,除此之外,對於上述反應過程及機制的推導,我們也利用一系列的碳同位素取代或是氘取代的有機起始物進行相關反應,進而得知其結果,並可成功的驗證我們所假設的反應機制。

並列摘要


Herein, we report that η5-pentadienyl ruthenium complex (η5-C5H7)(PPh3)2RuCl (1) is an efficient catalyst for the synthesis of 1,4-disubstituted butenynes in THF from the dimerization of aryl alkynes with a catalyst loading as low as 1-2 mol % under mild conditions, furnishing the (Z)-butenyne as the major product in the moderate yield along with a small amount of the E isomer. When aryl group which contains the substituent in the ortho position, the catalytic procedure results seem to indicate that the steric effect affects the yields of the desired enyne product more than the electronic effect. Dimerization reactions in different solvents showed that oxygen-containing solvents such as THF, diethyl ether, and acetone are better solvents than nitrogen-containing solvents. O-containing solvents are known to have relatively weaker coordinating power than the N-containing solvents. These results possibly indicate that the process could be assisted by the weak coordination between a solvent molecule and the metal center to stabilize the active intermediate. Treatment of a phenyl alkyne with 1 and KPF6, both in stoichiometric quantities, gives a phenyl phosphonium salt 6, whose structure has been confirmed. A series of synthesis of polyaryl phosphonium salts (APS) by cyclotrimerization of various aryl alkynes are also induced by a stoichiometric amount of the ruthenium η5-pentadienyl complex (η5-C5H7)(PPh3)2RuCl (1). A mechanism consisting of continuous insertion reactions of aryl alkynes into Ru-C bonds is proposed for the formations of enynes and APSs. In second study, catalytic cyclization reactions of three 2-ethynylphenyl vinyl ether 7a, 7b-Z and 7d in various alcohol are efficiently catalyzed by [Ru]Cl to give the benzoxepine derivatives, respectively. Surprisingly, in CH2Cl2, 7a and 7b containing no methyl and one methyl substituted vinyl groups undergo different skeletal rearrangement processes involving cleavage of C≡C and C=C bonds, respectively, in their reactions with [Ru]Cl. For both 7a and 7b, the terminal triple bonds are converted to the vinylidene ligands, then different [2+2] cycloadditions of the vinyl group with either the Cα=Cβ or the Ru=Cα bonds of the vinylidene ligand are proposed to take place. In the reaction of 7a, with no methyl group, the [2+2] cycloaddition process involves the vinylidene Cα=Cβ bond leading to formation of a bicyclic carbene intermediate followed by cleavage of the original C≡C triple bond, to give the cationic γ,δ-unsaturated vinylidene complex 9a which contains the trans-form double bond detected by coupling constant in NMR spectrum. The skeletal rearrangement of 7b-Z and -E, with one terminal methyl group on the vinyl unit, is believed to proceeds via a different [2+2] cycloaddition process involving the Ru=Cα bond, followed by cleavage of the C=C double bond of the original vinyl group to afford the carbene complex 14b. The structure of 14b is determined by single crystal X-ray diffraction analysis. Thus in the reaction of [Ru]Cl with a similar aryl vinyl ether 7c containing two terminal methyl groups on the vinyl unit, only the vinylidene complex 16c is isolated with no C-C bond formation. In addition, this catalytic cyclization is inhibited by the presence of a terminal methyl group on the vinyl unit trans to the phenolic oxygen atom as in the case of 7b-E. We also found that hydrolysis of i-propenyl phenyl ether to phenol probably occurs prior to cyclization to lead the formation of carbine complex 18d. Labeling experiments using 13C and 2D isotopes lead to better discernment of the skeletal rearrangement of the enyne system.

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