Lash T D, Werner T M, Thompson M L, Manley J M
Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, USA.
J Org Chem. 2001 May 4;66(9):3152-9. doi: 10.1021/jo010066s.
Porphyrins with fused aromatic rings are under detailed investigation due to their unique spectroscopic properties. To gain more insights into the effects due to ring annealation on the porphyrin chromophore, a series of fluoranthoporphyrins have been synthesized. Reaction of 3-nitrofluoranthene with isocyanoacetate esters in the presence of a phosphazene base afforded good yields of the fluorantho[2,3-c]pyrrole esters 8. Cleavage of the ester moiety with KOH in ethylene glycol afforded the parent heterocycle 9, and this condensed with 2 equiv of acetoxymethylpyrroles 10 in refluxing acetic acid-2-propanol to afford tripyrranes 11. Following cleavage of the tert-butyl ester protective groups with TFA, "3 + 1" condensation with pyrrole dialdehyde 12 gave the fluoranthoporphyrins 13 in good overall yields. In addition, reaction of tripyrrane 11 with acenaphthopyrrole dialdehyde 16 gave the mixed acenaphthofluoranthoporphyrin 17 in excellent yields. A difluoranthoporphyrin 18 was also prepared via a "2 + 2" MacDonald condensation. Reaction of fluoranthopyrrole 8a with dimethoxymethane in the presence of p-toluenesulfonic acid gave the symmetrical dipyrrylmethane 19, and following ester saponification, this was condensed with a dipyrrylmethane dialdehyde to afford the adj-difluoranthoporphyrin 18. The UV--vis spectra for these fluoranthoporphyrins gave a series of three broadened absorptions in the Soret band region, although the Q-bands were little effected by ring fusion. The nickel(II), copper(II), and zinc chelates were more unusual, showing strong absorptions near 600 nm. Difluoranthoporphyrin 18 showed many of the same spectroscopic features, although the presence of two ring fusions gave rise to an increase in the spectroscopic shifts. The mixed system 17 gave spectra that showed larger red shifts due to the acenaphthylene unit combined with the features due to the fluoranthene rings. This work further demonstrates the utility of aromatic ring fusion in altering the properties of porphyrinoid systems.
具有稠合芳环的卟啉因其独特的光谱性质而受到详细研究。为了更深入了解环退火对卟啉发色团的影响，已合成了一系列荧蒽卟啉。3-硝基荧蒽与异氰基乙酸酯在磷腈碱存在下反应，以良好的产率得到荧蒽并[2,3-c]吡咯酯8。用氢氧化钾在乙二醇中裂解酯部分得到母体杂环9，其与2当量的乙酰氧基甲基吡咯10在回流的乙酸-2-丙醇中缩合得到三吡咯11。用三氟乙酸裂解叔丁酯保护基后，与吡咯二醛12进行“3 + 1”缩合，以良好的总产率得到荧蒽卟啉13。此外，三吡咯11与苊并吡咯二醛16反应，以优异的产率得到混合的苊并荧蒽卟啉17。还通过“2 + 2”麦克唐纳缩合制备了二荧蒽卟啉18。荧蒽吡咯8a与二甲氧基甲烷在对甲苯磺酸存在下反应得到对称的二吡咯甲烷19，酯皂化后，其与二吡咯甲烷二醛缩合得到邻位二荧蒽卟啉18。这些荧蒽卟啉的紫外-可见光谱在Soret带区域给出了一系列三个变宽的吸收峰，尽管Q带受环稠合的影响很小。镍（II）、铜（II）和锌螯合物更不寻常，在600 nm附近显示出强吸收。二荧蒽卟啉18显示出许多相同的光谱特征，尽管两个环稠合的存在导致光谱位移增加。混合体系17给出的光谱显示出由于苊烯单元导致的更大红移以及荧蒽环的特征。这项工作进一步证明了芳环稠合在改变卟啉类体系性质方面的实用性。
