鈀催化2-苯甲醯呋喃之環化合成䓬酮衍生物

Abstract

䓬酮是環庚三烯酮的結構，常存在於天然物、藥物，同時也是作為進行高階環加成反應的合成原料。本篇論文探討在䓬酮環上具有芳香環融合化合物的合成。選擇2’-溴取代苯甲醯呋喃與2’’-溴取代苯甲醯呋喃化合物4作為起始物，利用鄰位上修飾溴取代基，藉由鈀金屬催化促使分子內進行合環反應而得到七圓環的架構，其中若最終產物上含有其他溴原子存在則會被鈀金屬進一步進行脫溴反應。合成出的多芳香環呋喃䓬酮5在紫外光的照射下會放出螢光，因此藉由紫外-可見光吸收光譜與螢光放光光譜來量測此類型衍生物的光學性質。 另外嘗試用金屬催化劑或路易斯酸等進行分子內脫氫耦合反應或朔爾類型反應建構䓬酮的七環架構。因此合成2-苯甲醯呋喃化合物6與7d，然而經過系列反應測試，並沒有得到預期的產物。化合物6經NaBH4還原反應可生成對應醇化合物，在路易斯酸的催化下意外獲得二聚物，並成功養出晶體鑑定結構。

Furotropone is a structure derived from tropone. Tropone is commonly found in natural substances and drugs, and it also serves as a synthetic raw material for conducting high-order cycloaddition reactions. 2'-bromobenzoylfuran and 2''-bromobenzoylfuran 4 were chosen as starting materials. By modifying the bromo substituent at the ortho position and utilizing palladium metal catalyst, an intramolecular cyclization reaction was induced, resulting in the formation of a seven-membered ring structure. If the final product contains additional bromine atom, they are further subjected to debromination by palladium catalyst. The synthesized polycyclic aromatic compound 5 exhibits fluorescence upon irradiation with ultraviolet light. Therefore, the optical properties of such derivatives were measured using ultraviolet-visible absorption spectroscopy and fluorescence emission spectroscopy. Furthermore, we attempted to construct seven-membered ring structure of tropone through intramolecular dehydrogenative coupling or Scholl-type reactions with the use of metal catalysts or Lewis acids. Therefore, 2-benzoylfuran derivatives 6 and 7d were synthesized and subjected to the investigation. However, the expected products were not obtained after a series of screening. Compound 6 underwent reduction with NaBH4 to yield the corresponding alcohol, which proceeded a dimerization pathway under Lewis acid conditions. The molecular structure of this dimerized produced was confirmed by crystallographic analysis.