Cyclization Reactions of Ruthenium Vinylidene Complexes with Terminal Aromatic Alkynes Containing Aldehyde, Ketone, and Ester Functionality

在本篇論文中，我們致力於研究半三明治釕金屬錯合物與含有羰基的芳香環末端炔有機化合物之間的反應並探討其中新穎有趣的化學。文中製備了一系列含有醛、酮、酯官能基的有機化合物(1a-c and 6)與釕金屬錯合物((η5-C5H5)(PPh3)2Ru-Cl)進行反應，進而探討不同的羰基取代對反應之影響。我們獲得了不同形式的環化產物，其中包含了六員環的含氧釕碳烯環錯合物(2)、含苯並呋喃的釕碳烯錯合物(3)、以及釕呋喃錯合物(11c和12a-c)。 以含有醛基的芳香環末端炔有機化合物1a與釕金屬錯合物進行反應，末端的炔基會先與釕金屬錯合物形成亞乙烯基錯合物的中間體II，再進行分子內的環合反應以得到六員環的釕金屬碳烯錯合物。藉著將有機化合物中的醛基官能基改變為酮基1b-c，則可得到以五員環的釕金屬碳烯錯合物3為主產物以及六員環的釕金屬碳烯錯合物2為副產物。其中所發生的反應是先經過一個三鍵的π配位釕金屬錯合物中間體並接著發生在Cβ碳上的環合反應，而這樣的反應過程主要是受到酮基官能基的取代而控制了反應途徑得到不同的產物。當我們更進一步將有機物上的取代基改變為酯基6時，釕金屬亞乙烯基錯合物7是可以被單離的。並且進一步的對釕金屬錯合物7在Cβ碳上進行去質子化反應與多種不同的烷基化反應，而得到釕金屬錯合物9a-c。接著將錯合物9利用鹼的去質子反應所引發的環化反應，可觀察到兩種不同的反應途徑而得到兩種不同的產物。在第一種反應途徑中，會經由一個形式上甲醇的脫去以及伴隨著一個sp2-sp2碳碳單鍵的形成而得到釕金屬錯合物12。在此反應過程中會經過兩個連續的分子內環合反應以及一個釕金屬亞乙烯基中間體V的過程。在第二種反應途徑中，釕金屬錯合物9c則是進行在Cα碳上的分子內環合反應並且伴隨著[1,3]苄基轉移，而得到釕金屬錯合物11c。而這兩種不同的反應途徑，可以藉著使用不同當量的鹼來控制。為了更進一步的了解上述的這些化學反應與其中的反應機制，我們除了使用NMR光譜鑑定之外也藉由兩顆釕金屬錯合物的X-ray晶體結構來證實我們的反應。Terminal arylalkynes containing aldehyde, ketone, and ester functionality (1a-c and 6), were reacted with [Ru]-Cl ([Ru] = (η5-C5H5)(PPh3)2Ru) to investigate the specific influence of different carbonyl groups. Dissimilar types of hetrocyclic complexes were obtained, including a six-membered ring alkoxycarbene complex 2 from 1, an isobenzofuran carbene complex 3 from 1, or furan complexes 11c and 12a-c from 6, respectively. For the o-alkynyl benzaldehyde 1a, the reaction with [Ru]-Cl takes place at the terminal alkyne first giving the vinylidene-intermediate II which could undergo an intramolecular cyclization to yield the six-membered ring carbene complex 2a. By changing the aldehyde gourp to a ketone group, the reaction gives the five-membered ring carbene complex 3 as the major product and the six-membered ring complex 2 as the minor product. The reaction proceeds via formation of a π-coordinated intermediate followed by a cyclization at Cβ. The presence of ketone group clearly controls the reaction pathway to give different products. For the ethynylbenzoate compound 6, the vinylidene complex 7 is isolated, and then deprotonation followed by alkylation with various haloacetates yield complex 9. Base induced cyclization of complex 9 leads to two types of products. In the first type, formation of complex 12, through a formal methanol elimination accompanied with one sp2-sp2 C-C bond formation, is via a tandem intramolecular cyclization and a vinylidene intermediate V. The intramolecular cyclization at Cα of complex 9c accompanied with a [1,3]-benzyl group migration process to yield complex 11c is the second type reaction. These two types of reaction pathways could be controlled by the amount of base used in the reaction. Better understanding of these chemical reactions and their mechanisms involved are corroborated by structure determination of the two ruthenium complexes using single crystal X-ray diffraction analysis