利用有機膦試劑作為催化劑對 1,3-二茚酮衍生物進行 β-位醯化反應 以查耳酮香豆素衍生物與醯氯試劑製備呋喃[3,2-c]香豆素衍生物:利用三丁基膦試劑誘導之一系列碳-醯化反應/合環反應 使用催化量三乙胺與膦試劑於化學選擇性的還原/Wittig 反應以合成高官能性的呋喃分子

Abstract

第一部分，利用催化量的有機膦試劑、醯氯以及三乙胺對其 β 位置進行直接地醯化反應。此合成策略也成功應用於 α,β- 不飽和內酯與內醯胺以及各系列五員環分子。此外醯化產物亦可簡單地透過與疊氮試劑的反應製備成噠嗪衍生物。 第二部分，將查耳酮香豆素衍生物和醯氯試劑在三丁基膦的誘導下經由一系列有趣的中間體的形成而轉換成 phosphorus ylide，再透過配合的試劑進一步地製備各系列呋喃[3,2-c]香豆素衍生物。透過各種控制實驗的結果分析與探討成功地剖析此反應機制。 第三部分，將 10 mol % 氧化膦試劑透過矽烷試劑的還原，應用於早期本實驗室開發的呋喃製成方法。透過一連串試劑的調整以及物理條件的優化，成功地屏除副反應路徑的發生，結合一系列高化學選擇性的還原反應、Michael 反應、氧醯化反應以及 intramolecular Wittig 反應於此方法學。In part I, we have developed an organophosphane-catalyzed direct β-acylation of a series of conjugated systems bearing ketone, amide and ester functionalities using acyl chlorides as trapping reagents. A wide variety of highly functional ketone derivatives were generated efficiently under very mild conditions with high yields according to our protocol. Our adducts can even be utilized as important building blocks for the synthesis of functional tri/tetracyclic pyridazine derivatives.

In part II, electrophilic addition of acyl chlorides to 3- cinnamoyl-4-hydroxy -2H-chromen-2-ones and subsequent Bu3P-mediated cyclization leads to highly functionalized furo[3,2-c]coumarins. The unprecedented cyclization reaction proceeds under mild reaction conditions within short reaction times (1 min to 1 h), and can be further applied in the synthesis of alkenyl-substituted furo[3,2-c]coumarins by the treatment with carbonyl electrophiles under basic conditions.

In part III, An efficient protocol for the synthesis of highly functionalized furans via intramolecular Wittig reaction has been developed using catalytic amounts of phosphine and triethylamine in the presence of silyl chloride, which served as the promoter to activate the phosphine oxide. Reduction of the activated phosphine oxide by hydrosilane resulted in the generation of phosphine, while the decomposition of conjugate acid of Et3N resulted in the regeneration of base, both of which mediated the formation of phosphorus ylide.