meso‐Trifluoromethyl‐Substituted Expanded Porphyrins

Abstract

A series of meso-trifluoromethyl-substituted expanded porphyrins, including N-fused [24]pentaphyrin 3, [28]hexaphyrin 4, [32]heptaphyrin 5, [46]decaphyrin 6, and [56]dodecaphyrin 7, were synthesized by means of an acid-catalyzed one-pot condensation reaction of 2-(2,2,2-trifluoro-1-hydroxyethyl)pyrrole (1) as the first examples bearing meso-alkyl substituents. Besides these products, porphyrin 2 and two calix[5]phyrins 8 and 9 were also obtained. [28]Hexaphyrin 4 was quantitatively oxidized to [26]hexaphyrin 14 with MnO(2). These expanded porphyrins have been characterized by mass spectrometry, (1)H and (19)F NMR spectroscopy, and UV/Vis spectroscopy. The single-crystal structures have been determined for 3, 4, 6, 7, and 14. The N-fused [24]pentaphyrin 3 displays a distorted structure containing a tricyclic fused moiety that is similar to those of meso-aryl-substituted counterparts, whereas 8 and 9 are indicated to take roughly planar conformations with an inverted pyrrole opposite to the sp(3)-hybridized meso-carbon atom. Both [28]- and [26]hexaphyrins 4 and 14 have figure-of-eight structures. Solid-state structures of the decaphyrin 6 and dodecaphyrin 7 are remarkable, exhibiting a crescent conformation and an intramolecular two-pitch helical conformation, respectively.

meso-Trifluoromethyl-substituted Subporphyrin from Ring-splitting Reaction of meso-Trifluoromethyl-substituted [32]Heptaphyrin(1.1.1.1.1.1.1)

“…The conformation of meso-tetrakis(perfluoroalkyl)porphyrin and their metal complexes have been often discussed. 10,13 While the crystal structure of 8 has been elusive, we have confirmed a severely ruffled structure for 8 by preliminary crystal structural analysis (SI), 15 which is consistent with its characteristic absorption spectrum. In summary, we isolated meso-trifluoromethyl-substituted B(III) subporphyrin 1 from the ring-splitting reaction of the corresponding [32]heptaphyrin.…”

“…This idea came from recent findings that expanded porphyrins sometimes undergo unique skeletal rearrangements upon metallation or heating, 7,8 which are probably aided by transannular ³-electron interac- 2 to produce B(III) meso-pentafluorophenyl subporphyrin. 9 It was thus thought that similar subporphyrin-extrusion from meso-trifluoromethyl [32]heptaphyrin 5 may occur upon suitable metallation, since 5 is known to take a figure-eight conformation, 10 being suitable for the transannular interaction at the hinge-position.…”

Figure‐Eight‐Strukturen, Möbius‐Bänder und mehr: Konformation und Aromatizität von Porphyrinoiden

“…[208,209] Beim Versuch, ein vollständig meso-substituiertes Pentaphyrin herzustellen, erhielt man lediglich die N-anellierten Systeme 27def-H und 28def-H 3 . [120,162,210,211] Diese Reaktion ließ sich verallgemeinern, denn später wurden auch N-invertierte Pentaphyrine zu einer Reihe von einfach und doppelt anellierten Makrocyclen umgesetzt. [164,212] 27def-H und 28def-H 3 sind zwei Oxidationsstufen des gleichen N-anellierten Pentaphyrins.…”

“…Ein anderes Dodecaphyrin, das CF 3 -substituierte 106c-H 8 , wurde kristallographisch untersucht und besaß einige besondere Strukturmerkmale. [211] Abbildung 17. Dreidimensionale Strukturen ausgewählter n-Phyrine(1 n ) nach Röntgenstrukturdaten.…”

A Stable Organic π‐Radical of a Zinc(II)–Copper(I)–Zinc(II) Complex of Decaphyrin

“…These spectral data indicate 46p-aromatic character for 6. [7,10] In the next step,w et ested metalation of 6 with Cu-(OAc) 2 ·H 2 Ointhe presence of sodium acetate in amixture of methanol and ethyl acetate at room temperature for 2h.T o our delight, we obtained ad ecaphyrin Zn-Cu-Zn trimetal complex, 7,in72% yield by simple direct recrystallization of the crude reaction mixture.H R-ESI-TOF-MS spectroscopy of 7 indicated the parent ion peak at m/z = 2620.8885 (calcd for C 110 H 20 N 10 F 50 63 Cu 1 64 Zn 2 [M] À :2620.8958). Thestructure of 7 was determined by X-ray crystallographic analysis to be essentially the same as that of 6 except the presence of the Cu ion coordinated by the pyrroles Ea nd J ( Figure 2).…”