- Porphyrins with exocyclic rings. Part 12. Synthesis of meso,β-butano- and meso,β-pentanoporphyrins from cycloalka[b]pyrroles
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Pyrroles 5 with b-face fused seven- or eight-membered carbocyclic rings were prepared in good yields by Knorr-type condensations with cycloheptanone or cyclooctanone, respectively. Treatment with lead tetraacetate in dichloromethane afforded the labile ω-acetates 8 and subsequent acid catalyzed condensation with α-unsubstituted pyrrole-2-carboxylates yielded the related pyrrolylcycloalka[b]pyrroles 29 and 30. The α-unsubstituted pyrroles 14 and 23 were prepared by condensing α,β-unsubstituted ketones, or their β-acetoxycarbonyl precursors, with benzyl N-tosylglycinate in the presence of DBU, followed by dehydration with POCl3-pyridine and base catalyzed elimination of p-toluenesulfinic acid. Dipyrrole dibenzyl esters 29 and 30 were hydrogenolysed over 10% Pd-C to give the corresponding dicarboxylic acids. Acid catalyzed condensation with diformyldipyrrylmethane 33 under modified MacDonald '2 + 2' conditions afforded a series of four cycloalkanoporphyrins 4a-d with seven- or eight-membered exocyclic rings. Although the meso,β-butanoporphyrins 4a and 4b were isolated in good yields, poorer results were obtained for the related meso,β-pentanoporphyrin: 4c and 4d. It is proposed that the eight-membered carbocyclic ring distorts the geometry of the open-chain tetrapyrrolic intermediates and this deleterious influence results in the lower yields observed.
- Bastian, Jolie A.,Lash, Timothy D.
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p. 6299 - 6310
(2007/10/03)
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- Synthesis and properties of 5-(p-carbomethoxyphenyl)-15-(p-dimethylaminophenyl)porphyrin
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An unsymmetrically substituted 5,15-diarylporphyrin 1, with p-dimethylamino and p-carbomethoxy substituents, was synthesized via a MacDonald condensation of aryldipyrromethane precursors 6 and 12, which were prepared in good yield by three or four step pr
- Zindel,Lightner
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p. 1219 - 1223
(2007/10/02)
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- Regioselective synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates from benzyl isocyanoacetate
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A general synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates was developed based on the reaction of β-nitroacetates with benzyl isocyanoacetate. The advantage of this route over other pyrrole syntheses was the regiochemical control of the substitution pattern on the pyrrole ring.
- Ono,Katayama,Nisyiyama,Ogawa
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p. 707 - 710
(2007/10/02)
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- Synthesis of pyrroles from benzyl isocyanoacetate
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Benzyl esters of 5-unsubstituted pyrrole-2-carboxylic acids were prepared in excellent yields by the base-catalyzed condensation of benzyl isocyanoacetate with α-acetoxynitro compounds, or nitro-alkenes, in refluxing tetrahydrofuran. These pyrrolic products are important intermediates in the synthesis of porphyrins and related compounds.
- Lash,Bellettini,Bastian,Couch
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p. 170 - 172
(2007/10/02)
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- Photoinduced Electron Transfer in Porphyrin-Quinone Cyclophanes, 6. - Porphyrin-Quinone Cyclophanes with Gradually Varied Acceptor Strength: Syntheses and Characterizations
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For studying intramolecular electron-transfer reactions, three groups of double- and single-bridged porphyrin-quinone cyclophanes 1-4, 5-9, and 11-14, resp., with gradual variation of quinone acceptor strengths were synthesized.As key intermediates for bu
- Staab, Heinz A.,Weiser, Juergen,Futscher, Michael,Voit, Guido,Rueckemann, Andreas,Anders, Christine
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p. 2285 - 2302
(2007/10/02)
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- Syntheses of Methyl-devinylporphyrins Related to Protoporphyrin -IX. Initial Studies on the Mechanism of the Copper(II) Catalysed Cyclization of 1',8'-Dimethyl-a,c-biladiene Salts
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Using copper(II) catalysed cyclization of a,c-biladiene dihydrobromide salts, porphyrins related to protoporphyrin-IX dimethyl ester (8), but in which both vinyls are replaced with methyls, or where either the 2- or 4-vinyls are individually replaced with methyls, are synthesized.These compounds are required for reconstitution of the corresponding hemes into hemoproteins, to enable the study of the rotational disorder of prosthetic heme groups in reconstituted hemoproteins.By way of 13C n.m.r. spectroscopy of enriched a,c-biladienes and porphyrins, the copper(II) catalysed cyclization of 1',8'-dimethyl-a,c-biladiene dihydrobromides is shown to afford porphyrins in which one of the 1'- and 8'-methyl groups becomes the new linking meso carbon atom.
- Smith, Kevin M.,Kehres, Lisa A.
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p. 2329 - 2335
(2007/10/02)
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