利用一價銠金屬催化1,6-烯炔環化反應以及進行苄位烷基銠之1,4-轉移

Abstract

本論文探討利用1,6-烯炔起始物進行銠金屬催化串聯合環反應。在此反應設計中，我們著重研究1,6-烯炔起始物16與苯硼酸試劑S-3b進行反應。反應機構如下:首先銠催化劑與苯硼酸試劑S-3b進行轉移金屬化後，和起始物16上反應性較好的三鍵進行選擇性1,2-加成後，馬上進行分子內環化反應形成苄位烷基銠中間體。銠金屬從苄位sp3碳進行1,4-轉移至另一個苄位sp3碳上及最後進行β-甲氧基消去反應，形成苯乙烯產物17。This thesis investigates a rhodium-catalyzed cascade reaction employing a 1,6-enyne as the starting material. Through systematic experimentations, our focus lay on a cascade reaction invovling the 1,6-enyne 16 and 4-methoxyphenylboronic acid S-3b. The proposed reaction mechanism entails initial transmetalation of S-3b with the rhodium catalyst. The resulting arylrhodium intermediate undergoes regioselective 1,2-addion to the alkyne moiety of the substrate. Subsequent intramolecular cyclization affords a benzylic all rhodium species, which undergoes a 1,4-shift to the benzylic position before B-methoxy elimination, yielding the desired product 17.