含雙環丙烷釕金屬亞丙烯基錯合物之反應的研究

Abstract

釕金屬錯合物和帶有雙環丙基的丙炔醇化合物，在六氟磷酸鉀的存在下，進行反應生成帶有雙環丙基的釕金屬丙烯基錯合物2。藉由2與催化量鹵鹽之反應可得到帶有五員環的亞乙烯基錯合物3。此擴環反應是藉由鹵鹽在2之三員環上的親核加成，接著以鹵鹽作為離去基並伴隨著碳碳單鍵之生成。 錯合物2亦可在水的存在下與氟硼酸進行反應並生成帶有七員環的烷氧基碳烯錯合物4。此反應之機制係先進行開環反應接著進行分子內合環反應並伴隨著碳氧鍵的生成。此外，將4進一步地進行去質子化可輕易地得到中性錯合物5。 有鑑於以上所述的兩個實驗結果，我們將2與鹵鹽並同時有氟硼酸的存在的條件下進行反應。根據所使用的反應溶劑之不同，我們可得到兩種不同的反應產物並且都具有良好的產率。當使用的溶劑為四氫呋喃時，我們可得到帶有五員環之釕金屬亞乙烯基錯合物6並同時伴隨著碳碘鍵之生成。有趣的是，當使用的溶劑為二氯甲烷時，我們得到的是帶有雙3-碘丙基之釕金屬亞乙烯基錯合物7並伴隨著氫氣加成反應的發生，我們推測由鹵鹽與氟硼酸反應而得之類硼烷物種HBX2為參與此反應之還原劑。若將7與作為鹼之吡啶反應可得到帶有五員環之釕金屬亞乙烯基錯合物8，此反應之機制係藉由連續性的去質子化及分子內合環反應兩個步驟所完成。在氟硼酸的催化下，錯合物3可與甲醇溶劑分子進行加成反應得到9並伴隨著開環反應的發生。錯合物2之三號碳可被格里納試劑如烯丙基溴化鎂攻打而形成中性的乙炔基錯合物10，此外藉由10的質子化可產生亞乙烯基錯合物11，並可再經由自發性的分子內歧化反應而得到亞乙烯基錯合物12。 我們也探討了錯合物2與各種不同胺類之間的反應。根據胺類本身的立障大小而有不同的反應結果。若錯合物2分別與三乙基胺及吡啶反應可使三員環開環並得到帶正電性的乙炔基錯合物13及14。若使用的是乙基胺，則會先在錯合物2之三號碳上進行親核加成反應，接著藉由逆烯反應而得到釕金屬碳烯錯合物15。此外，錯合物2與2-乙炔基吡啶在六氟磷酸銨的存在下可反應生成特別的帶有雙陽離子及九員環的亞乙烯基錯合物16。此反應途徑為先進行開環反應而後再進行9-endo-dig的合環反應。為了在鄰近三員環之碳上引進親核中心，我們首先先將化合物1藉由酸的催化得到開環產物1,3-烯炔17，接著藉由將17進行環氧化反應而得到化合物18。在六氟磷酸銨的存在下，18與[Ru]Cl在甲醇溶劑中可反應生成帶有五員環之烷氧基碳烯錯合物19，不幸的是，我們並沒有得到任何三員環之開環產物。

The ruthenium allenylidene complex tethering two cyclopropyl rings [Ru]=C=C=C(C3H5)2 (2, [Ru] = Cp(PPh3)2Ru) is synthesized from the reaction of [Ru]Cl with dicyclopropyl propargylic alcohol 1 in the presence of NH4PF6 in CH2Cl2. Treatment of 2 with a catalytic amount of sodium iodide affords the ruthenium vinylidene complex 3 with concomitant formation of a five-membered ring. This ring expansion reaction proceeds via a nucleophilic attack of iodide anion on the cyclopropyl ring of 2, followed by a subsequent C-C bond formation with the iodide serving as a leaving group. Complex 2 was treated with acid HBF4 in the presence of water to yield the seven-membered ring alkoxy carbene complex 4 with concomitant formation of a C-O bond. This reaction proceeds via a ring opening process followed by an intramolecular cyclization with a C-O bond formation. Furthermore, deprotonation of 4 easily generated the neutral complex 5. Reactions of 2 with iodide are explored in the presence of HBF4. Depending on the choice of solvent, two different products are obtained in good yields. The ruthenium vinylidene complex 6 bearing a five-membered ring is obtained via a ring opening of two cyclopropyl rings with the formation of a C-I bond in THF. Interestingly, the ruthenium vinylidene complex 7 tethering two linear 3-iodopropyl groups is obtained in CH2Cl2. HBI2, formed via the reaction of iodide anion with HBF4, is proposed to be the reducing agent. Treatment of 7 with base, such as pyridine, afforded the five-membered ring ruthenium vinylidene complex 8. This reaction proceeds via a deprotonation followed by an intramolecular cyclization process. Addition of MeOH to complex 3 is accompanied with a ring opening in the presence of HBF4 giving complex 9. Grignard reagents such as allylmagnesium bromide attacks on C3 of 2 to give the neutral acetylide complex 10, furthermore, protonation of 10 affords the vinylidene complex 11, which undergoes an intriguing intramolecular metathesis reaction to generate the vinylidene complex 12. Reactions of 2 with various nucleophilic amines as nucleophiles were also investigated. Ring opening reactions of the cyclopropyl group of 2 by bulky amines, such as triethylamine and pyridine, lead to the cationic ruthenium acetylide complexes 13 and 14, respectively. On contrary, if a primary amine, such as ethylamine, was used, the ruthenium carbene complex 15 was obtained via nucleophilic attack of the amine on C3 of 2 followed by a retro-ene process. In addition, the dicationic cyclic vinylidene complex 16 containing a nine-membered ring is obtained from the reaction of 2 with 2-ethynylpyridine in the presence of NH4PF6 in acetonitrile. This reaction proceeds via a ring-opening process followed by a 9-endo-dig cyclization. To introduce a nucleophilic center proximal to cyclopropyl ring, we synthesized compound 18 from epoxidation of 1,3-enyne 17, which is the ring opening product of 1 catalyzed by acid. The reaction of 18 with [Ru]Cl in the presence of NH4PF6 in MeOH yields the alkoxy carbene complex 19 with a five-membered ring. Unfortunately, the product from the ring opening of the cyclopropyl ring is not obtained.