18- and 22-π-Electron macrocycles containing furan, pyrrole, and thiophen rings

Modifying the porphyrin core — a chemist's jigsaw

“…The introduction of heteroatoms other than nitrogen also varies the chemical properties, e.g., an oxygen causes a pronounced electronic effect in the macrocyclic system due to its electronegativity and a sulfur atom perturbs the planar structure due to its steric bulkiness. Meso-unsubstituted heteroporphyrins are accessible through the "3+1" method and have first been reported by Broadhurst (Scheme 3) [28,29]. For meso-tetraaryl heteroporphyrins the "3+1" method is not suitable and mostly Lindsey [30] conditions are used (Scheme 4a).…”

“…Both compounds 51 and 52 comprise a heterocyclic ring containing either identical or different heteroatoms. By the previous method meso-unsubstituted dithia, dioxo or mixed heteroatomporphyrins 53 are accessible [5,28,29,54]. The access to meso-aryl diheteroporphyrins was first described by Ulman [55] in 1975 (Scheme 14b).…”

A Benzodipyrrole‐Derived Sapphyrin

“…Currently, we are exploring further extensions of this theme, for instance, by targeting the replacement of the dipyrrole moiety with other aromatic and heteroaromatic subunits. 1 3 , T = 173(2) K, Z = 2, GOF on F 2 = 0.853, R 1 (I > 2s(I)) = 0.0646, wR 2 = 0.1298. The crystal was attached to glass fibers and mounted on a Bruker SMART diffractometer equipped with graphite monochromated Mo Ka (l = 0.71073 ) radiation, operating at 50 kV and 30 mA, and a CCD detector; 45 frames of two-dimensional diffraction images were collected and processed to obtain the cell parameters and orientation matrix.…”

“…The synthesis and anion-binding properties of sapphyrins have been reviewed recently. [6] The most common synthesis of sapphyrins is the so-called 3+2 approach reported by Broadhurst et al, [1] and this approach has successfully been employed to obtain a range of alkyl-and meso-substituted sapphyrins. [7][8][9][10][11][12] A less common but equally attractive approach is the so-called 4+1 approach, which relies on the use of a tetrapyrrolic precursor and formylpyrroles.…”

“…Since the first report of expanded porphyrins, namely a pentapyrrolic aromatic macrocycle referred to as sapphyrin, [1] various other oligopyrrole macrocycles including pentaphyrins, hexaphyrins, and rubyrins have been synthesized and characterized.…”