Facile Synthesis of 13¹-Oxo-porphyrins Possessing Reactive 3-Vinyl or 3-Formyl Group, Protochlorophyll-a/dDerivatives by 17,18-Dehydrogenation of Chlorins

Abstract

<jats:p> Methyl protopyropheophorbides-a/d were prepared by modification of readily available chlorophyll-a. The key step was oxidation of 13<jats:sup>1</jats:sup>-oxo-chlorin to the corresponding porphyrin, and 2,3-dichloro-5,6-dicyano-p-benzoquinone was effective for 17,18-dehydrogenation. A reduction in oxidation potential of the chlorin was necessary for the oxidation. Facile oxidation was achieved by insertion of zinc as the central metal, reduction of the 13-carbonyl group and/or aggregation by high concentration. The synthetic 13<jats:sup>1</jats:sup>-oxo-porphyrins had vinyl and formyl groups at the 3-position. These groups were very reactive in the molecule and selectively converted to other functional groups. </jats:p>

Self-aggregation of Synthetic Protobacteriochlorophyll-d Derivatives¶

“…The resulting residue was purified with FCC (1.5% MeOH-CH 2 Cl 2 ) to give pure 1 (3 1 R/S 5 1/1, 45 lmol, 25.2 mg) in 67% yield; see spectral data of 1 in Ref. 23.…”

“…The resulting residue was purified with FCC (1% MeOH-CH 2 Cl 2 ) to give pure 2 (35 lmol, 19.2 mg) in 52% total yield from 5; 2: melting point 258-2608C (from CH 2 Cl 2 and hexane); VIS (THF) k max 5 637 (relative intensity, 0.01), 584 (0.05), 562 (0.08), 521 (0.05), 430 (0.53), 417 (1.00) nm; see other spectral data of 2 in Ref. 23.…”

Erythrocytes Membrane Photodestruction Sensitized Chlorophyll a Derivatives: Some Structure-Activity Regularities

“…methyl-13(1)-desoxopyropheophorbide a (15) [55] were obtained according to literature procedures. Methyl-13(1)-hydroxy-13(1)desoxo-pheophorbide a (18), [57] chlorin e 6 13(1)-N-(2-hydroxyethyl)amide-15(3),17(3)-dimethyl ester (24), [58] chlorin e 6 13(1)-morpholinylamide-15(3),17(3)-dimethyl ester (25), [58] rodin g 7 13(1)-N,N-dimethylamide-15(3),17(3)-dimethyl ester (34), [59] chlorin e 6 13(1),17(3)-N,N'-(2-hydroxyethyl)diamide-15(3),17(3)-dimethyl ester (32), [60] and chlorin e 6 13(1),15(2),17(3)-N,N',N''-(2-hydroxyethyl)triamide (33) [60] were also obtained according to the known procedures.…”

Self‐aggregation of Synthetic Protobacteriochlorophyll‐d Derivatives¶

“…Methyl protobacteriopheophorbide ‐d ( 1 ). According to reported procedures (23), Zn‐4 was transformed to 1 as follows. To a distilled acetone solution (40 mL) of Zn‐4 (3 1 R/S = 1/1, 67 μmol, 42.1 mg) was slowly added a distilled acetone solution (20 mL) of 2,3‐dichloro‐5,6‐dicyano‐benzoquinone (DDQ; 100 μmol, 27.7 mg), and the reaction mixture was stirred at room temperature.…”

“…Methyl 3 1 ‐demethyl‐protobacteriopheophorbide ‐d ( 2 ). Zinc metallation of chlorin 5 (67 μmol, 36.9 mg) gave Zn‐5 (see below), which was DDQ oxidized and zinc demetallated (see above) to afford porphyrin 8 (23). The resulting residue containing 8 without purification by FCC was dissolved in dry dichloromethane (20 mL) and reduced by t ‐BuNH 2 BH 3 (335 μmol, 29.1 mg).…”