Conjugated Macrocycles Related to the Porphyrins. 21. Synthesis, Spectroscopy, Electrochemistry, and Structural Characterization of Carbaporphyrins
作者:Timothy D. Lash、Michael J. Hayes、John D. Spence、Melanie A. Muckey、Gregory M. Ferrence、Lisa F. Szczepura
DOI:10.1021/jo020267b
日期:2002.7.1
albeit in low yields ranging from 5 to 8%. These hybrid bridged annulene structures have porphyrin-like electronic absorption spectra with strong Soret bands near 420 nm and a series of Q-bands through the visible region. The proton NMR spectrum confirms the presence of a strong diamagnetic ring current, and the meso-protons show up at 10 ppm, while the internal CH is shielded to approximately -7 ppm
麦当劳缩合反应的“ 3 +1”变体已被证明是合成碳卟啉的极佳方法。特别地,在TFA存在下,1,3-二烯二甲醛与三吡喃缩合,在用DDQ氧化后,以优异的产率得到一系列苯并羰基卟啉。三甲酰基环戊二烯也可提供碳卟啉产物,尽管收率低,从5%到8%。这些杂化的桥接环结构具有类似卟啉的电子吸收光谱,在420 nm附近具有很强的Soret带,并且在可见光区有一系列Q带。质子NMR光谱证实存在强反磁性环电流,中质子出现在10 ppm处,而内部CH被屏蔽到大约-7 ppm。碳卟啉用TFA进行可逆的质子化。尽管在中等浓度的TFA存在下观察到质子化物质的混合物,酸的初始添加提供了单阳离子。但是,在存在50%TFA的情况下,会生成C质子化的指示。这些指示剂通过苯并咔唑卟啉的苯并部分重新定位pi脱位途径,因此尽管它们仍然保留了强大的大环电流,但仍代表了桥接的苯并[18]环烯。已经制备了带有稠合和菲环的碳卟啉,前者在紫