Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, USA.
J Org Chem. 2012 Mar 2;77(5):2368-81. doi: 10.1021/jo2026977. Epub 2012 Feb 10.
A "2 + 2" strategy for synthesizing adj-dicarbaporphyrinoid systems has been developed. In a model study, an azulenylmethylpyrrole dialdehyde was condensed with a dipyrrylmethane in the presence of HCl, followed by oxidation with ferric chloride, to give a modest yield of an azuliporphyrin. Fulvene aldehydes were prepared by reacting an indene-derived enamine with azulene aldehydes in the presence of Bu(2)BOTf, and azulene dialdehydes similarly reacted to give fulvene dialdehydes. The dialdehydes were condensed with dipyrrylmethanes in TFA/dichloromethane to afford good to excellent yields of dicarbaporphyrinoids with adjacent indene and azulene subunits. These 22-carbaazuliporphyrins exhibited significant diatropic character, and this property was magnified upon protonation. These characteristics are attributed to tropylium-containing resonance contributors that possess 18π electron delocalization pathways. Protonation studies demonstrated that C-protonation readily occurred at the interior indene carbon, but deuterium exchange also occurred at the internal azulene CH as well as at the meso-positions with TFA-d. Reaction of a carbaazuliporphyrin with silver(I) acetate in methanol or ethanol solutions also gave unusual nonaromatic dialkoxy derivatives.
已经开发出一种“2+2”策略来合成 adj-二碳卟啉系统。在模型研究中，用盐酸将薁基甲基吡咯二醛与二吡咯甲烷缩合，然后用三氯化铁氧化，得到中等产率的薁卟啉。富烯醛是通过在 Bu(2)BOTf 的存在下，使来源于茚的烯胺与薁醛反应制备的，类似地，薁二醛反应得到富烯二醛。将这些二醛在 TFA/二氯甲烷中与二吡咯甲烷缩合，得到邻位有茚环和薁环的二碳卟啉衍生物，产率良好至优秀。这些 22-碳薁卟啉表现出显著的反磁各向异性特征，质子化后这种性质会增强。这些特性归因于含有薁鎓的共振贡献物，它们具有 18π 电子离域途径。质子化研究表明，C-质子化容易在内部茚环碳上发生，但氘交换也发生在内部薁 CH 以及 TFA-d 的均三甲苯位置上。在甲醇或乙醇溶液中，碳卟啉与醋酸银反应也得到了不寻常的非芳香性二烷氧基衍生物。
