Efficient synthesis of monoacyl dipyrromethanes and their use in the preparation of sterically unhindered trans-porphyrins.
Efficient synthesis of monoacyl dipyrromethanes and their use in the preparation of sterically unhindered trans-porphyrins.
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DOI：
10.1002/chin.200022096
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发表时间：
2000-01
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影响因子：
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通讯作者：
Polisetti Dharma Rao;B. Littler;and G. Richard Geier;Jonathan S. Lindsey
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文献类型：
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作者：
Polisetti Dharma Rao;B. Littler;and G. Richard Geier;Jonathan S. Lindsey
醛与在5-位带有空间上不受阻碍的芳基取代基的二吡咯甲烷的缩合通常导致低产率和衍生自酸解乱序的卟啉产物的混合物。我们已经开发了一个简洁的nonscrambling合成这样的反式卟啉，利用多克量的dipyrromethanes的可用性。该路线包括用吡啶基硫酯选择性地单酰化二吡咯甲烷，将单酰基二吡咯甲烷还原成相应的甲醇，以及甲醇的自缩合形成卟啉。单酰化过程具有广泛的范围，如通过制备一组15种不同的单酰基二吡咯甲烷在多克规模下以良好的收率所证明的。在温和的室温条件下，二吡咯甲烷甲醇的自缩合反应非常迅速（<3 min），并以16-28%的产率提供反式卟啉。通过激光解吸质谱法（LD-MS）对来自粗反应混合物的样品进行分析，结果显示在检测限（1/100）内无干扰。自缩合与一系列吸电子或释放电子的取代基以及用于结构单元应用的取代基（TMS-乙炔、乙炔、碘、酯）相容。在自缩合中不存在任何可检测的扰乱使得能够进行简单的纯化。该合成容易地在涉及最少色谱的过程中提供克量的纯的、空间上不受阻碍的反式卟啉。
The condensation of an aldehyde with a dipyrromethane bearing a sterically unhindered aryl substituent at the 5-position typically results in low yield and a mixture of porphyrin products derived from acidolytic scrambling. We have developed a concise nonscrambling synthesis of such trans-porphyrins that takes advantage of the availability of multigram quantities of dipyrromethanes. This route involves the selective monoacylation of the dipyrromethanes with a pyridyl thioester, reduction of the monoacyl dipyrromethane to the corresponding carbinol, and self-condensation of the carbinol to form the porphyrin. The monoacylation procedure has wide scope as demonstrated by the preparation of a set of 15 diverse monoacyl dipyrromethanes in good yield at the multigram scale. The dipyrromethanecarbinol self-condensation reaction is extremely rapid (<3 min) under mild room-temperature conditions and affords the trans-porphyrin in 16-28% yield. Analysis by laser-desorption mass spectrometry (LD-MS) of samples from the crude reaction mixture revealed no scrambling within the limit of detection (1 part in 100). The self-condensation is compatible with a range of electron-withdrawing or -releasing substituents as well as substituents for building block applications (TMS-ethyne, ethyne, iodo, ester). The absence of any detectable scrambling in the self-condensation enables a simple purification. The synthesis readily affords gram quantities of pure, sterically unhindered trans-porphyrins in a process involving minimal chromatography.