使用活性烷烴分子、醛類分子以及三丁基膦製備多官能性的磷兩性離子:合成多取代的呋喃[3,2-c]香豆素

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2012

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  本論文之內容主要是在探討利用簡易的酸鹼對作為催化劑,並且使用三丁基膦 (tributylphosphine) 作為 trapping reagent 製備出磷兩性離子。先將 4-羥基香豆素 (4-hydoxycoumarin) 和醛類 (aldehydes) 在吡咯啶 (pyrrolidine) 以及苯甲酸 (benzoic acid) 的催化下,做柯諾瓦諾格 (Knoevenagel) 縮合反應。三丁基膦當作親核試劑行 Michael addition 反應,即可得到具有多官能基的磷兩性離子(functionalized phosphorus zwitterions)。此磷兩性離子大部分非常穩定,可以經由簡易的管住層析純化。其反應時間大多在 2.5 小時內,其產率大部分在 88-98%。只有少數的兩個例子產率較低,分別為對苯二甲醛以及乙醛酸乙酯,50 以及 69%。反應時間為 0.5 小時和16 小時。   另一方面,將本實驗室在 2010 年開發的呋喃合成方法,應用在此磷兩性離子上,合成出多取代的呋喃[3,2-c]香豆素(Furo[3,2-c]coumarins)。磷兩性離子和醯氯 (acyl chlorides) 以及三乙基氨 (triethylamine) 進行分子內 Wittig 反應,合成出多取代的呋喃[3,2-c]香豆素(polysubstituted furo[3,2-c]coumarins)。此反應之應用即為 2010 年本實驗室開發之多取代呋喃的合成方法。此方法非常地便利且溫和,反應中可配合不同的醯氯和兩性磷分子。交叉排列組合下,可製備出非常多有趣的呋喃[3,2-c]香豆素化合物。其反應時間在0.5-17 小時;產率在 76-99%。
A novel synthetic protocol for the preparation of functional phosphorus zwitterions via organocatalytic three-component reactions of activated alkanes, aldehydes, and tributylphosphine has been successfully developed. A wide variety of functional alkanes and aldehydes can be successfully employed, and numerous corresponding phosphorus zwitterions can be generated in the presence of tributylphosphine and catalysts, such as pyrrolidine and benzoic acid, in high yields. The reaction mechanism is supposed to be via the organocatalytic Knoevenagel condensation reactions of activated alkanes and aldehydes followed by the Michael addition of tributylphosphine towards the in-situ formed Michael acceptors. Most of these phosphorus zwitterions are stable under the atmosphere and can be purified (flash-column chromatography). For example, when 4-hydroxycoumarin was treated with aldehydes (except terephthalaldehyde 93p or ethyl glyoxalate 93l) according to our developed protocol, the corresponding adducts can be provided within 0.5-2.5 h in 88-98% isolated yields. Terephthalaldehyde 93p or ethyl glyoxalate 93l had poor reactivities in our designed methodology, affording the corresponding adduct 115ap or 115al within 0.5 or 16 h in 69% or 50%, respectively. Furthermore, one type of these new phosphorus zwitterions can be further utilized as the precursors for the synthesis of functional furo[3,2-c]coumarins according to the protocols for the preparation of furans developed in our group in 2010. Various polysubstituted furo[3,2-c]coumarins were successfully synthesized starting from the corresponding phosphorus zwitterions, acid chlorides, and triethylamine via intramolecular Wittig reactions (0.5-17 h; 79-99% isolated yields).

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磷兩性離子, , 呋喃[3, 2-c]香豆素, Phosphorus zwitterion, phosphine, furo[3, 2-c]coumarin

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