Decapitation of dihydroporphyrazinediol derivatives: synthesis and X-ray structure of a novel seco-porphyrazine

Luk’yanets

et al. 2003

Chemistry A European J

Benzene- or 2,3-naphthalene-ring-expanded tetraazachlorins (TACs), tetraazabacteriochlorins (TABCs), and tetraazaisobacteriochlorins (TAiBCs) have been synthesized by using tetramethylsuccinonitrile as a source of hydrogenated sites. The derived compounds were characterized by using NMR spectroscopy, X-ray crystallography, electronic and magnetic circular dichroism (MCD) spectroscopy, and electrochemical and spectroelectrochemical methods. X-ray analysis revealed that the benzene-fused TAiBC deviates slightly from planarity at the hydrogenated sites as a result of the presence of sp(3) carbons, which prefer a nonplanar tetrahedral conformation. The spectral data were analyzed by using a band deconvolution technique. In the electronic absorption spectra of TAC and TABC species, the Q band splits into two intense components and smaller splittings were observed for the 2,3-naphthalene-fused derivatives relative to the benzo-fused species. In contrast, in the case of TAiBCs, the Q band splitting was apparently not observed in absorption spectra, as expected from the C(2v) molecular symmetry. However, MCD signals of the Q band in TAiBCs showed Faraday B terms, implying that the accidental degeneracy of the LUMO and LUMO+1 was broken even for adjacently ring-fused species. Relative molecular orbital energies were estimated by using cyclic and differential pulse voltammetry. The first reduction potentials were close for TACs and TABCs, although those of TAiBCs shifted to more negative potentials. In contrast, although TABCs and TAiBCs exhibited similar first oxidation potentials, those of TACs appeared at more positive potentials. These properties were reproduced and rationalized by molecular orbital and configuration interaction calculations within the framework of the ZINDO/S Hamiltonian. DFT-level frequency calculations have succeeded in reproducing the IR spectra for low-symmetry tetraazaporphyrin (TAP) derivatives for the first time. The relationship between structures and spectral features is discussed.

Section: Introductionmentioning

confidence: 99%

Synthesis and Spectroscopic and Electrochemical Studies of Novel Benzo‐ or 2,3‐Naphtho‐Fused Tetraazachlorins, Bacteriochlorins, and Isobacteriochlorins

Fukuda

Luk’yanets

et al. 2003

Chemistry A European J

“…The only previous attempt [3] to prepare hydrogenated tetraazaporphine (or porphyrazine, TAP) derivatives by catalytic hydrogenation of alkyl-substituted MgTAP in the presence of Pd black gave the corresponding TAC derivative (but not TABC as the authors stated). Recently, Hoffman and co-workers [4] described the synthesis of dihydroporphyrazinediol by reacting unsymmetrical TAP with osmium tetroxide. This diol was subjected to reaction with nickel acetate in the presence of dioxygen to give the novel secoporphyrazine.…”

Section: Introductionmentioning

confidence: 99%

New synthesis of tetraazachlorins and tetraazabacteriochlorins by Diels–Alder reaction of tetraazaporphine

J. Porphyrins Phthalocyanines

Korolyova

Tok

et al. 2000

The use of the Diels–Alder reaction of unsubstituted tetraazaporphine as dienophile with some dienes of the anthracene series for the synthesis of novel substituted tetraazachlorins, tetraazabacteriochlorins and tetraazaisobacteriochlorins is reported. The condensation of tetraazaporphine with anthracene, 9,10-dimethyl- or 2,6-di(tert-butyl)anthracene in boiling chlorobenzene gives novel dibenzobarreleno-substituted tetraazachlorins 3–5 in yields of up to 71%. When AlCl3 was used as catalyst in the reaction of tetraazaporphine with 2,6-di(tert-butyl) anthracene, the corresponding cis- and trans-dibenzobarreleno-substituted tetraazabacteriochlorins 6a and 6b were obtained. The reaction of tetraazaporphine with the more active diene 2,3-benzanthracene at 130°C gives mainly benzonaphtho[2,3-b]barreleno-substituted tetraazachlorin 7, while the same reaction conducted at 220°C led to a mixture of cis- and trans isomers of tetraazabacteriochlorins 8a and 8b and tetraazaisobacteriochlorins 9a and 9b. The products were characterized using elemental analysis data and mass, 1H NMR and visible spectra. The effect of hydrogenation of one or two double bonds of the tetraazaporphine macrocycle on the electronic absorption spectra is discussed.

“…The high reactivity of the quasi-isolated C β =C β double bond in the TAP macrocycle was used by Nie et al [30] for the synthesis of cis-dihydroxy-TACs (78, 79) via the OsO 4 mediated dihydroxylation of TAP 80 and 81, respectively (Scheme 15). Interestingly, diol 78 underwent nickel-mediated air oxidation and subsequent loss of two β-carbons of one pyrrole ring to give seco-TAP (82); diol 79 produced a higher yield of 82 when reacted in air under similar conditions.…”

Section: Transformation Of Tetraaza-por Phines Into Hydrotetraaza-pormentioning

confidence: 99%

Design and synthesis of tetraazachlorins, tetraazabacteriochlorins and tetraazaisobacteriochlorins

J. Porphyrins Phthalocyanines

Luk’yanets

2009

Three approaches to the synthesis of reduced derivatives of tetraazaporphine such as tetraazachlorin, tetraazabacteriochlorin, and tetraazaisobacteriochlorin are reviewed. The fi rst synthesis of alkyl-substituted tetraazachlorins was achieved by the catalytic hydrogenation of magnesium complexes of tetraazaporphines. Two other synthesis approaches for reduced tetraazaporphines based on the mixed condensation of the precursors with different hydrogenation levels and β-β addition reactions have been developed in the last decade. The use of tetramethylsuccinonitrile as the saturated component in the mixed condensation with derivatives of aromatic and heteroaromatic dicarboxylic acids enable the synthesis of oxidation-resistant benzo-; 1,2-and 2,3-naphtho-; pyrazino-; 2,3-and 3,4-pyridinofused tetraazachlorins, tetraazabacteriochlorins, and tetraazaisobacteriochlorins. Fullerene conjugates of reduced tetraazaporphine derivatives were obtained using 1,2-dicyanofullerene as the source of the hydrogenated sites. Tetraazaporphine can act as dienophile in Diels-Alder reaction with dienes of the anthracene and cyclopentadiene series and also as dipolarophile in 1,3-dipolar cycloadditions with azomethine ylides and nitrones. In addition, the effect of the reduction of peripheral double bonds in tetraazaporphine macrocycle alone, and in combination with annelation of benzene or heterocyclic rings on the absorption spectra is discussed.