Energy & Fuels 1993, 7, 172-178
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Recent Advances in the Synthesis of Porphyrins with Five-Membered Exocyclic Rings Timothy D. Lash,* Desiree M. Quizon-Colquitt, Craig M. Shiner, Thanh H. Nguyen, and Zao Hu Department of Chemistry, Illinois State University, Normal, Illinois 61 761-6901 Received September 10,1992. Revised Manuscript Received November 6, 1992
New approaches to the synthesis of petroporphyrins bearing five-membered exocyclic rings are described. The key intermediates in these studies were cyclopenta[blpyrroles, which were synthesized in one step from cyclopentanone. Reaction with lead tetraacetate gave acetoxy derivatives and further acid-catalyzedcondensation with a-unsubstituted pyrroles gave a series of 6-pyrrolylcyclopenta[bl pyrroles in excellent yields. These dipyrrolic intermediates were converted into meso-pethanoporphyrins in moderate to good yields by the MacDonald condensation and the b-bilene approach, and this work has led to a new synthesis of deoxophylloerythroetioporphyrin(DPEP). Ongoing studies directed toward the synthesis of methylethanoporphyrins and fused ring "diDPEP's" are also reported.
Introduction Detailed studies of various organic-rich sediments, such as oil shales and petroleum, have revealed the presence of complex mixtures of metal10porphyrins.l-3 Porphyrins with diverse carbon skeletons have been isolated and characterized from sedimentary materials and the terms "petroporphyrins" and "geoporphyrins" have been coined to describe these compounds. Many petropprphyrins bear exocyclicrings consistingof five, six, or seven carbon atoms. Synthetic samples of cycloalkanoporphyrins are of value in corroborating petroporphyrin structures. In addition, the availability of pure porphyrin samples allows the chemical, physical, chromatographic, and spectroscopic properties of these geological compounds to be examined. Our earlier studiesP12in the petroporphyrin area were (1) (a) Baker, E. W.; Palmer, S. E. In The Porphyrins; Dolphin, D., Ed.; Academic Press: New York 1978; Vol. 1, pp 486-552. (b) Callot, H. J. In The Chlorophylls; Scheer, H., Ed.; CRC Press: Boca Raton, FL, 1991; pp 339-364. (2) (a) Filby; R. H.; Van Berkel; G. J. In Metal Complexes in Fossil Fuels. Geochemistry, Characterization, and Processing: Filby, R. H., Branthaver, J. F., Eds.; American Chemical Society: Washington, DC, 1987; pp 2-37. (b) Chicarelli, M. I.; Kaur, S.; Maxwell, J. R. Ibid. pp 40-67. (c) Ocampo, R.; Callot, H. J.; Albrecht, P. Ibid. pp 68-73. (3) (a) Callot, H. 3.; Ocampo, R.; Albrecht, P. Energy Fuels 1990,4, 635-639. (b) Verne-Mismer, J.; Ocampo, R.; Bauder, C.; Callot, H. J.; Albrecht, P. Energy Fuels 1990,4,639-643. (c) Keely, B. J.; Prowse, W. G.; Maxwell, J. R. Energy Fuels 1990,4,628-634. (d) Eckardt, C. B.; Keely, B. J.; Waring, J. R.; Chicarelli, M. I.; Maxwell, J. R. Philos. Trans. R. SOC.London B 1991,333,339-348. (e) Ocampo, R.; Bauder, C.; Callot, H. J.; Albrecht, P. Geochim. Cosmochim. Acta 1992, 56, 745-761. (4) Lash, T. D. Org. Geochem. 1989, 14, 213-225. (5) Lash, T. D.; Balasubramaniam, R. P.; Catarello, J. J.; Johnson, M. C.; May, D. A., Jr.; Bladel, K. A.; Feeley, J. M.; Hoehner, M. C.; Marron, T. G.; Nguyen, T. H.; Perun, T. J., Jr.; Quizon, D. M.; Shiner, C. M.; Watson, A. Energy Fuels 1990,4, 668-674. (6) Lash, T. D.; Bladel, K. A.; Johnson, M. C. Tetrahedron Lett. 1987, 28, 1135-1138. (7) Lash, T. D.; Bladel, K. A.; Shiner, C. M.; Zajeski, D. L.; Balasubramaniam, R. P. J. Org. Chem. 1992,57, 4809-4820. (8)Lash, T. D.; Perun, T. J., Jr. Tetrahedron Lett. 1987, 28, 62656268. (9) Lash, T. D. Tetrahedron Lett. 1988,29, 6877-6880. (10) Lash, T. D.; Johnson, M. C. Tetrahedron Lett. 1989, 30, 56975698. (11) Lash, T. D.; Balasubramaniam, R. P. Tetrahedron Lett. 1990,31, 7545-7548. (12) (a) May, D. M., Jr.; Lash, T. D. J. Org. Chem. 1992,57,4820-4828.
(b) Lash, T. D. Energy Fuels, preceding paper in this issue.
0887-0624/93/2507-0172$04.00/0
mostly directed toward the synthesis of porphyrins with six-membered, seven-membered, or larger exocyclic rings. However, the most widespread sedimentary cycloalkanoporphyrins incorporate five-membered exocyclic rings (e.g., structures 1-6, usually in the form of the nickel or
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Mr
vanadyl chelates), primarily because the chlorophylls are major biological precursors to fossil porphyrin pigments.l Deoxophylloerythroetioporphyrin (1; DPEP) was first tentatively identified by Treibs13 in the 1930s and commonly occurs as a major component of petroporphyrin extracts. The 13l-methylderivative of DPEP (2) has been extracted and characterized from Gilsonite bitumenzb and the related 132-methylcompound 3 has been isolated and (13) (a) Treibs,A.JustwLiebigsAnn.Chem. 1934,510,42. (b) Treibs, A.Angew.Chem. 1936,49,682. ThestrudureofDPEPhasbeenconfirmed by proton NMR spectroscopy and X-ray crystallography. See: Quirke, J. M. E.; Maxwell, J. R.; Eglinton, G.; Sanders, J. K. M. Tetrahedron Lett. 1980,21,2987-2990. Fookes, C. J. R.J. Chem. Soc., Chem. Commun. 1983, 1472-1473. Ekstrom, A.; Fookes, C. J. R.; Hambley, T.; Loeh, H. J.; Miller, S. A.; Taylor, J. C. Nature 1983,306,173-174. Shulga, A. M.; Serebrennikova, 0. V.; Mozzhelina, T. K. Neftekhimiya 1986,26, 309. For the structure elucidation of closely related petroporphyrins, see also: Storm, C. B.; Krane, J.; Skjetne,T.;Telnaes, N.;Branthaver, J.F.;Baker, E. W. Science 1984, 223, 1075-1076. Chicarelli, M. I.; Maxwell, J. R. Tetrahedron Lett. 1984, 25,4701-4704.
0 1993 American Chemical Society
Recent Advances in the Synthesis of Porphyrins provisionallyidentified from Julia Creek oil shale.14 Other fossil porphyrin structures include the tetrahydrobenzoDPEP 4,15the chlorophyll c derived petroporphyrin 5,16 and the bacteriopetroporphyrins 6.17 The latter series of sedimentary porphyrins were isolated from the Messel oil shale17and are believed to be molecular fossils of bacteriochlorophylls d. Due to the central importance of DPEP, the synthesis of this compound has been widely examined. A partial synthesis of DPEP from chlorophyll a has been reported,18 and this was adapted for the preparation of a 17-propyl DPEP derivativelgaand 17-desethylDPEP.lgb In addition, partial syntheses of bacteriopetroporphyrins have been described by Smith and Smith.20 The first total synthesis of DPEP was reported by Fischer and Hofmann in 1936.21 In this study, trace amounts of porphyrin (
