有機金屬釕、鉑應用於有機分子進行環化反應之研究

Organoruthenium and Platinum Mediated Intramolecular Cyclization Reactions

羅清郁(Ching-Yu Lo)

指導教授 ： 劉瑞雄

國立清華大學/理學院/化學系/博士(2006年)

https://doi.org/10.6843/NTHU.2006.00188

摘要

本論文分成五章，主要是利用過渡金屬釕及鉑催化或促進非環狀的有機小分子化合物進行環化反應。

第一章是利用釕金屬錯合物TpRuPPh3(CH3CN)Cl作為催化劑，加入三乙胺作為添加劑，將環氧炔類分子環化形成?喃架構之環化反應，並可應用在含有各式官能基的環氧炔類，且大幅地改善了文獻中產率不佳的缺點，並以同位素氘的標定反應結果，推測反應機構中生成了釕金屬丙二烯基錯合物。
第二章介紹以釕金屬錯合物TpRuPy2Cl作為催化劑，在相當溫和的條件下，將環氧乙烷化合物進行順式及反式間之異構化反應，而二者間平衡的比例，則取決於分子間的立體位向；當我們以具有手性的環氧乙烷化合物進行反應，並不會失去光學活性，說明了反應是在環氧化合物靠活化官能基的碳上進行反應，這個反應的發現，大幅地增加了環氧乙烷化合物在有機合成上的應用方式。
第三部份是以釕金屬TpRu(CH3CN)2PPh3PF6為催化劑，以甲苯為溶劑，在80 ΟC下反應12-18小時，可以催化苯環烯炔類化合物進行環化異構化反應，並經由碳鏈骨架的重排而得到indene的產物。我們並進行了一系列的同位素氘及碳13的標定反應，證實了反應生成了釕金屬丙二烯基中間體後，再經過5-endo-dig的環化反應，並包括了「亞甲基環丙烷-三亞甲基甲烷」這個重排反應。
第四章則是研究鉑金屬PtCl2催化苯環烯二炔類進行芳香化反應，經由加入氫鹵酸，生成了雙二烯基的中間產物99-Cl至99-I，並經由6π電子環化反應，得到奈的產物，利用這個方法，我們在奈的產物中直接導入了鹵素官能基，大幅地增加了產物的應用性。
第五章是以cis-2,4-dien-1-als這種烯醛類架構的分子為主，以鉑金屬PtCl2，或是鈀金屬催化劑，可以具有選擇性的環化得到2-環戊烯酮、3-環戊烯酮或是呱喃的產物，這個新的金屬催化反應，增加了cis-2,4-dien-1-als架構分子的應用價值，我們並以同位素反應，推測出了合理的反應機構。

關鍵字

有機金屬 ； 釕 ； 鉑 ； 環化反應 ； 催化反應

並列摘要

Chapter I

This chapter deals with ruthenium-catalyzed synthesis of furan epoxyalkyne functionality. Ruthenium catalyst TpRuPPh3(CH3CN)Cl effected the cyclization of epoxyalkynes to furans in the presence of Et3N. The reactions worked well for various epoxyalkynes with suitable oxygen and nitrogen functionalities with low loading of catalyst. It failed with disubstituted epoxyalkynes. The mechanism was elucidated by a deuterium labelling experiment and involved a ruthenium-vinylidenium intermediate.
Chapter II

Chapter II describes ruthenium catalyzed cis-trans isomerization of epoxide. Ruthenium catalyst TpRuPy2Cl was effective for cis-trans isomerization of various functionalized epoxides. Enantiospecific isomerization of chiral epoxides is achieved without loss of enantiopurity, and epimerization occurs only at the epoxide carbon of the activating group. The mechanism of isomerization involves cleavage of the C-O bond at the epoxide carbon of the activating group. SN2 attack of the epoxide by ruthenium is proposed as the key step. This isomerization enhances the usefulness of epoxides in organic synthesis.
Chapter III

This chapter discusses ruthenium catalyzed cycloisomerization of (o-ethynyl)styrenes. Treatment of a series of 2’,2’-disubstituted (o-ethynyl)styrenes with TpRu(CH3CN)2PPh3PF6 ( 10 mol %) in benzene (80 °C, 12-18h) efficiently gave 2-alkenyl-1H-indene derivatives. This catalytic reaction represents an atypical enyne cycloisomerization with skeletal rearrangement of starting enyne, where the C=C bond is completely cleaved and inserted by the terminal alkynyl carbon. The reaction mechanism was elucidated by a series of deuterium and 13C labeling experiments, as well as by changing the substituents at the phenyl moieties. The mechanism is proposed to involve the following key steps: 5-endo-dig cyclization of ruthenium-vinylidene intermediate, a nonclassical ion formation, and the “methylenecyclopropane-trimethylenemethane” rearrangement.
Chapter IV

Bergman type of cyclization of 1,2-bis(ethynyl)benzene via hydrohalogenation is described in this chapter. Treatment of 1,2-bis(ethynyl)benzene (91) with aqueous HX (X = Br, I) in hot 3-pentanone (100-105 °C, 2h) afforded 1,2-bis(1’-haloethenyl)benzene species 99-Br and 99-I in 98% and 95% yields, respectively. The hydrochlorination of endiyne 91 failed to proceed at elevated temperature but was implemented efficiently by PtCl2 (5 mol%) in hot 3-pentanone (100 °C, 2h) to give 1,2-bis(1’-chloroethenyl)benzene 99-Cl in 80% yield. In the presence of PtCl2 (5 mol %), these halides 99-Cl,99-Br and 99-I were subsequently converted to 1-halonaphthalenes 100-Cl,100-Br and 100-I in the mothersolution via sequential 6-p electrocyclization and dehalogenation reactions. PtCl2 (5 mol%) also effected direct haloaromatization of endiyne 91 with HX (X = Cl, Br, I) and gave 1-halonaphthalenes 100-Cl,100-Br and 100-I in 64-71% yields. Scope and regioselectivity of haloaromatization of various enediynes catalyzed by PtCl2 has investigated.
Chapter V

Last chapter describes PtCl2 (5 mol%) catalyze cycloisomerization of cis-2,4-dien-1-al. Chemselective cycloisomerization of cis-2,4-dien-1-als to 3- cyclopentenones and 4-alkylidene-3,4-dihydro-2H-pyran was achieved using PtCl2 and PdCl2(PhCN)2 respectively. In the presence of p-TSA catalyst, PtCl2 led to formation of conjugated 2-cyclopentenones. These new metal-catalyzed
reaction highlights the synthetic utility of cis-2,4-dien-1-als with the availability of various carbocyclic and oxygen heterocyclic compounds. A plausible mechanism is proposed on the basis of reaction observation and isotope-labeled experiment.

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