J. Am. Chem. Soc. 2000, 122, 12393-12394
12393
Scheme 1. Examples of Co-Mediated [2 + 2 + 2]
Cycloaddition Reactions of Ethyne-Containing Porphyrin
Structures with 1,6-Heptadiynea
Transition-Metal-Mediated [2 + 2 + 2]
Cycloaddition Reactions with Ethyne-Containing
Porphyrin Templates: New Routes to Cofacial
Porphyrin Structures and Facially-Functionalized
(Porphinato)metal Species
James T. Fletcher and Michael J. Therien*
Department of Chemistry
UniVersity of PennsylVania
Philadelphia, PennsylVania 19104-6323
ReceiVed January 14, 2000
ReVised Manuscript ReceiVed August 21, 2000
The diverse reaction chemistry generated by the limited number
of metalloenzyme catalytic motifs arises from rigorous definition
of active-site environments by the protein matrix. Rigidly fixing
the spatial arrangement of metal ligands and the relative proximity
of electronically disparate transition-metal centers thus constitute
challenging aspects of biologically inspired catalyst design. In
this report, we exploit the finesse of metal-mediated cycloaddition
reaction chemistry to build well-defined (porphinato)metal struc-
tures.1,2 An exemplary set of such reactions is described that utilize
alkyne-elaborated porphyrinic reactants, demonstrating that such
transformations offer new opportunities for engineering catalytic,
chromophoric, and supramolecular properties of structures based
on these macrocycles.
Metal-catalyzed cross-coupling reaction schemes3,4 provide
straightforward entry into both monomeric and oligomeric por-
phyrin-based structures that feature augmented conjugation.5,6 As
such, ethyne-containing porphyrinic cycloaddition templates I-IV
were prepared readily from appropriately halogenated (porphi-
nato)zinc(II) species;4,5 Scheme 1 highlights the products formed
when I-IV are reacted with 1,6-heptadiyne in the presence of
Co2(CO)8.7
Reaction of I-III under the conditions described in Scheme 1
constitutes a powerful new route into cofacial porphyrin com-
pounds. Since the first reports of these remarkable species,8 only
minor methodological advancements have been made with respect
a Reagents and conditions: 4:1 toluene:dioxane, 100 °C. (i) I (67 µmol),
1,6-heptadiyne (670 µmol), Co2(CO)8 (134 µmol), (87%); (i) II (43 µmol),
1,6-heptadiyne (430 µmol), Co2(CO)8 (86 µmol), (85%);(iii) III (25 µmol),
1,6-heptadiyne (500 µmol), Co2(CO)8 (100 µmol), (87%);(iv) IV (64
µmol), 1,6-heptadiyne (1.28 mmol), Co2(CO)8 (128 µmol), (64%).
Experimental details available as Supporting Information.
(1) (a) Vollhardt, K. P. C. Angew. Chem., Int. Ed. Engl. 1984, 23, 539-
556. (b) Schore, N. E. Chem. ReV. 1988, 88, 1081-1119. (c) Lautens, M.;
Klute, W.; Tam, W. Chem. ReV. 1996, 96, 49-92.
(2) Chromophore syntheses have employed Diels-Alder strategies to
elaborate the macrocycles of porphyrins and related pigments (see, for
example: (a) Callott, H. J.; Johnson, A. W.; Sweeney, A. J. Chem. Soc., Perkin
Trans. 1 1973, 1424-1427. (b) Cavaleiro, J. A. S.; Neves, M. G. P. M.; Tome´,
A. C.; Silva, A. M. S.; Faustino, M. A. F.; Lacerda, P. S.; Silva, A. M. G. J.
Heterocycl. Chem. 2000 37, 527-534 and references therein).
to the conventional pyrrole and aldehyde condensation routes to
rigidly linked cofacial porphyrin structures;9 this has both limited
the range of electronic structural modifications possible in such
constructs and required considerable synthetic effort to build
related, rigid face-to-face structures that comprise more than two
porphyrin units.10
(3) (a) Heck, R. F. Acc. Chem. Res. 1979, 12, 146-151. (b) Kumada, M.
Pure Appl. Chem. 1980, 52, 669-678. (c) Negishi, E.-I.; Luo, F. T.; Frisbee,
R.; Matsushita, H. Heterocycles 1982, 18, 117-122. (d) Stille, J. K. Angew.
Chem., Int. Ed. Engl. 1986, 25, 508-524.
(4) (a) DiMagno, S. G.; Lin, V. S.-Y.; Therien, M. J. J. Am. Chem. Soc.
1993, 115, 2513-2515. (b) DiMagno, S. G.; Lin, V. S.-Y.; Therien, M. J. J.
Org. Chem. 1993, 58, 5983-5993. (c) Hyslop, A. G.; Kellett, M. A.; Iovine,
P. M.; Therien, M. J. J. Am. Chem. Soc. 1998, 120, 12676-12677.
(5) (a) Lin, V. S.-Y.; DiMagno, S. G.; Therien, M. J. Science 1994, 264,
1105-1111. (b) Lin, V. S.-Y.; Therien, M. J. Chem.-Eur. J. 1995, 1, 645-
651. (c) LeCours, S. M.; DiMagno, S. G.; Guan, H.-W.; Therien, M. J. J.
Am. Chem. Soc. 1996, 118, 11854-11864. (d) LeCours, S. M.; DiMagno, S.
G.; Therien, M. J. J. Am. Chem. Soc. 1996, 118, 11854-11864.
(6) (a) Zhou, X.; Tse, M. K.; Wan, T. S. M.; Chan, K. S. J. Org. Chem.
1996, 61, 3590-3593. (b) Jiang, B.; Yang, S.-W.; Barbini, D. C.; Jones, W.
E., Jr. Chem. Commun. 1998, 213-214. (c) Arnold, D. P.; James, D. A. J.
Org. Chem. 1997, 62, 3460-3469. (d) Blake, I. M.; Anderson, H. L.; Beljonne,
D.; Bre´das, J.-L.; Clegg, W. J. Am. Chem. Soc. 1998, 120, 10764-10765.
(7) (a) Hillard, R. L., III, Vollhardt, K. P. C. J. Am. Chem. Soc. 1977, 99,
4058-4069. (b) Chiusoli, G. P.; Costa, M.; Zhou, Z. Gazz. Chim. Ital. 1992,
122, 441-449.
Meso-to-meso ethyne-bridged I serves as a precursor to V,
which features a ligand motif closely related to the 1,2-
diporphyrylphenylene frameworks shown by Naruta to support
metal-catalyzed homogeneous oxidation of water.11 An X-ray
crystallographic structure of V‚(MeOH)2 is shown in Figure 1.
Interestingly, Osuka has reported the structure of 1,2-bis[5′-(15′-
(p-tolyl)porphinato]zinc(II)]benzene, which features coplanar
(porphinato)zinc(II) units that manifest a minimal 3.43 Å average
(9) (a) Osuka, A.; Nakajima, S.; Nagata, T.; Maruyama, K.; Toriumi, K.
Angew. Chem., Int. Ed. Engl. 1991, 30, 582-584. (b) Collman, J. P.; Tyvoll,
D. A.; Chng, L. L.; Fish, H. T. J. Org. Chem. 1995, 60, 1926-1931.
(10) (a) Wasielewski, M. R.; Niemczyk, M. P.; Svec, W. A. Tetrahedron
Lett. 1982, 23, 3215-3218. (b) Abdalmuhdi, I.; Chang, C. K. J. Org. Chem.
1985, 50, 411-413. (c) Nagata, T.; Osuka, A.; Maruyama, K. J. Am. Chem.
Soc. 1990, 112, 3054-3059.
(8) (a) Collman, J. P.; Elliott, C. M.; Halbert, T. R.; Tovrog, B. S. Proc.
Natl. Acad. Sci. U.S.A. 1977, 74, 18-22. (b) Chang, C. K.; Kuo, M.-S.; Wang,
C.-B. J. Heterocycl. Chem. 1977, 14, 943-945. (c) Kagan, N. E.; Mauzerall,
D.; Merrifield, R. B. J. Am. Chem. Soc. 1977, 99, 5484-5486.
(11) Naruta, Y.; Sasayama, M.; Sasaki, T. Angew. Chem., Int. Ed. Engl.
1994, 33, 1839-1841.
10.1021/ja0001557 CCC: $19.00 © 2000 American Chemical Society
Published on Web 11/23/2000