釕金屬誘發含異原子有機烯炔化合物之環化反應的研究

Study on Intramolecular Cyclization of Organic Hetero-Containing Enynes Induced by Ruthenium Metal Complexes

羅濟賢(Ji-Xian Lo)

指導教授 ： 林英智

國立臺灣大學/理學院/化學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.00436

摘要

本篇論文探討藉由釕金屬錯合物誘發含異原子1,8-烯炔化合物進行分子內環化反應而形成含氧雜環產物。利用釕金屬錯合物[Ru]Cl ([Ru] = Cp(PPh3)2Ru)與尾端烯類官能基有甲基取代的化合物1反應，可得到含氧七環的釕金屬亞乙烯基錯合物3。此反應經由亞丙二烯中間體接著由親電性加成環化在Cγ上，並且是一溫和的反應過程。因為在乙烯上有甲基取代，因此環化所形成的中間體有三級碳陽離子的生成而穩定此過程。利用金屬錯合物3在乙腈中加熱或將[Ru]NCCH3+和化合物1在氯仿下加熱，皆可產生環化烯炔產物6。此外，相同的反應在氯仿及甲醇的共溶劑環境下，經由甲氧基親核加成而得到二次環化有機產物7a。另一方面，使用末端烯類官能基有兩甲基取代的化合物2a與[Ru]Cl進行反應，得到以反式為主要產物的錯合物8，。將[Ru]NCCH3+和化合物2a在氯仿加熱可生成11a (反式：順式＝2/1)。推測此反應機制是經由六元環椅式過渡態，而使得立體障礙為主要的選擇性因素。因此，使用含有較大的五環取代基化合物2b，可使得異構體比例大大的增加為10：1.8。在溶劑為甲醇的環境下，化合物2a可產生相對應的雙環化合物12和錯合物13。錯合物3和8加入甲醇鈉可分別得到相對應的乙炔基錯合物4和9。此外，將錯合物3和8加入烷基化試劑可分別得到相對應的亞乙烯基錯合物5a-b和10.

關鍵字

釕金屬 ； 催化 ； 雜環 ； 烯炔 ； 亞乙烯基

並列摘要

The intramolecular cyclization of 1,8-enyne containing hetero-atom mediated by ruthenium complex, leading to the formation of the oxygen heterocycle is described. In the [Ru]Cl-induced ([Ru] = Cp(PPh3)2Ru) reactions of enyne 1, with an internal methyl group on the olefinic group, the vinylidene complex 3 containing an oxepane moiety, bonded at Cβ is isolated. The reaction proceeds via the formation of an allenylidene intermediate followed by a cyclization at Cγ under mild condition. Stabilization of the cationic charge by the presence of methyl substituents clearly controls the reaction pathway. The reaction of 3 with NaOMe produces the acetylide complex 4. The alkylation of 4 by allyl bromide and methyl iodide as alkylation reagents induced the formation of 5a and 5b, respectively. Heating complex 3 in CH3CN or treatment of 1 with [Ru]NCCH3+ in CHCl3 at 50 °C gave the organic enyne 6 as the cyclized product. Furthermore, the same reaction in CHCl3/MeOH leads to the organic product 7a by tandem cyclization, formed possibly via sequential allenylidene/vinylidene cyclization followed by a nucleophilic addition of a methoxide.
In the reaction of [Ru]Cl with enyne 2a, containing two terminal methyl groups on the olefinic parts, the vinylidene complex 8 with a new oxane ring is obtained as a mixture of two diastereoisomers and the anti-isomer is the major product. Mild thermolysis of 2a in CHCl3 at 50 °C in the presence of [Ru]NCCH3+ gave 11a (anti-11a/syn-11a = 2/1). The proposed mechanism is via the formation of a six-membered ring chair-like transition state with the most bulkiest group in the pseudoequatorial position to reduce the 1,3 diaxial interactions. Hence, in the reaction of propargylic alcohol 2b, the isomer ratio was greatly improved to 10:1.8 due to the steric effect of the bulkier cyclopentyl tether. Treatment of 2a with [Ru]NCCH3+ in MeOH afforded two products, the hexahydro isochromene compound 12 with a methoxide group and the carbene complex 13, both containing a newly formed bicyclic ring. The same reaction of 2b in MeOH afforded no corresponding bicyclic ring products, but 11b was obtained. Similarly, the reaction of 8 with NaOMe produces the acetylide complex 9 and alkylation of 9 by allyl bromide as alkylation reagent gives 10.

並列關鍵字

Ruthenium ； catalysis ； heterocycle ； enyne ； vinylidene.

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