Synthesis of a Phlorin from a Meso‐Fused Anthriporphyrin by a Diels–Alder Strategy

Abstract

An anthracene-containing meso-fused carbaporphyrin, which has extended π-conjugation pathways as compared to the corresponding naphthalene-containing carbaporphyrin, has been synthesized. The weak global aromaticity of the anthriporphyrin also allowed its use as the diene for a Diels-Alder reaction with dimethyl acetylenedicarboxylate (DMAD). The resulting phlorin contains an interesting bicyclic structure. Moreover, to the best of our knowledge, this phlorin is the first Diels-Alder adduct of a diene forming part of the global π-conjugation pathway of an aromatic porphyrinoid.

Reversible π-system switching of thiophene-fused thiahexaphyrins by solvent and oxidation/reduction

“…The spectrum of 6 in CH 2 Cl 2 also displays a weak Soret-like band at 487 nm and a broad Q-like band at 712 nm. These features are analogous to those of nonaromatic 20 , 21 and phlorin-type porphyrinoids, 22 which are consistent with the dominant nature of their cross-conjugated π-networks. In addition, as observed in the 1 H NMR spectra, the absorption spectra of 5 also exhibit the remarkable solvent effect (Fig.…”

Polycyclic Aromatic Hydrocarbon‐/Heterocycle‐Embedded Porphyrinoids

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 Cho and co-workers reported the synthesis of thia-2,9anthriporphyrin 22 as shown in Scheme 4. [22] The precursor, 5-(2-formylanthracene-9-yl)thiophene-2-carbaldehyde 24 was synthesised by reacting of 9-bromo-2-anthraldehyde 23 with (5- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 formylthiophen-2-yl)boronic acid 18 in the presence of Pd(0) catalyst in DMF/H 2 O under Suzuki coupling conditions. The 9thienylanthracenediols 25 were synthesized by treating 24 with appropriate aryl bromides under Grignard reaction conditions.…”

“…Cho and co‐workers reported the synthesis of thia‐2,9‐anthriporphyrin 22 as shown in Scheme . The precursor, 5‐(2‐formylanthracene‐9‐yl)thiophene‐2‐carbaldehyde 24 was synthesised by reacting of 9‐bromo‐2‐anthraldehyde 23 with (5‐formylthiophen‐2‐yl)boronic acid 18 in the presence of Pd(0) catalyst in DMF/H 2 O under Suzuki coupling conditions.…”

Synthesis of a Phlorin from a Meso‐Fused Anthriporphyrin by a Diels–Alder Strategy

“…[27] Thus,t he free bases 4 and 5 were treated with palladium(II) acetate according to Scheme 1. After chromatographic purification of the products,the inner NH and CH signals disappeared, and no dramatic chemical-shift changes were observed in the 1 HNMR spectra of complexes Pd-4 and Pd-5,t hus confirming the metal coordination without major skeletal modifications.T he high-resolution mass spectrum (HRMS) of phlorin 5 has ab ase peak at m/z 942.1741 (calcd for C 56 H 40 N 2 O 4 SPd [M] + :9 42.1744), thus further confirming the formation of mononuclear complex Pd-5.The structure of Pd-4 was further supported by single-crystal X-ray diffraction [16] (see Figures S10 and S11) and HRMS measurements.T he "NNCS" (nitrogen-nitrogen-carbon-sulfur) mixed donors in the core of carbaporphyrin 4 afforded ad iamagnetic square-planar complex through coordination to palladium(II).…”

“…Thestructure of the anthriporphyrin 4 was unambiguously elucidated by X-ray crystallographic analysis after crystal growth from CH 2 Cl 2 /n-hexane ( Figure 2). [16] Theatoms of the anthracene moiety deviate from the mean plane of the macrocycle defined by C5, C10, C15, and C19 by ab road range of distances (0.05-1.42 ;s ee also Figure S8 in the Supporting Information). Thenear-planar anthracene moiety (composed of rings A, B, and C) is tilted by 31.468 8 from the mean plane (see Figure S9) to avoid steric repulsion between H2 and H21.…”