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Mechanism of Cyclopropanation Reactions Mediated by (5,10,15,20-Tetra-P- Tolylporphyrinato)Osmium(II) Complexes Christopher G

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Mechanism of Cyclopropanation Reactions Mediated by (5,10,15,20-Tetra-P- Tolylporphyrinato)Osmium(II) Complexes Christopher G View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Digital Repository @ Iowa State University Chemistry Publications Chemistry 10-2001 Mechanism of Cyclopropanation Reactions Mediated by (5,10,15,20-Tetra-p- tolylporphyrinato)osmium(II) Complexes Christopher G. Hamaker Illinois State University Jean-Pierre Djukic Universite Louis Pasteur Daniel A. Smith Goshen College L. Keith Woo Iowa State University, [email protected] Follow this and additional works at: http://lib.dr.iastate.edu/chem_pubs Part of the Chemistry Commons The ompc lete bibliographic information for this item can be found at http://lib.dr.iastate.edu/ chem_pubs/757. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Chemistry at Iowa State University Digital Repository. It has been accepted for inclusion in Chemistry Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Mechanism of Cyclopropanation Reactions Mediated by (5,10,15,20-Tetra-p-tolylporphyrinato)osmium(II) Complexes Abstract Catalytic systems derived from [Os(TTP)]2 or Fe(TTP) (TTP = 5,10,15,20-tetra-p-tolylporphyrinato) are extremely efficient at converting styrenes and diazo reagents to cyclopropanes in high yields and high stereoselectivity. A number of mechanistic studies have been undertaken to elucidate the catalytic pathway. A mono(carbene) complex, (TTP)OsCHCO2Et, has been isolated but is not the catalytically active species. An electron-withdrawing ligand trans to the carbene in (TTP)OsCHCO2Et activates the carbon fragment toward transfer to an olefin. Labeling studies with (TTP)OsCHX and N2CHY and substrate reactivity profiles are consistent with a trans-osmium(II) bis(carbene) species as the active catalyst. Disciplines Chemistry Comments Reprinted (adapted) with permission from Organometallics 20 (2001): 5189, doi:10.1021/om010787h. Copyright 2001 American Chemical Society. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/chem_pubs/757 Organometallics 2001, 20, 5189-5199 5189 Mechanism of Cyclopropanation Reactions Mediated by (5,10,15,20-Tetra-p-tolylporphyrinato)osmium(II) Complexes Christopher G. Hamaker,† Jean-Pierre Djukic,‡ Daniel A. Smith,§ and L. Keith Woo*,| Department of Chemistry, Campus Box 4160, Illinois State University, Normal, Illinois 61790-4160, Laboratoire de Syntheses Metallo-induitessUMR 7513 CNRS, Universite Louis Pasteur, 4, rue Blaise Pascal, 67070 Strasbourg, France, Department of Chemistry, Goshen College, Goshen, Indiana 46526, and Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111 Received August 29, 2001 Catalytic systems derived from [Os(TTP)]2 or Fe(TTP) (TTP ) 5,10,15,20-tetra-p- tolylporphyrinato) are extremely efficient at converting styrenes and diazo reagents to cyclopropanes in high yields and high stereoselectivity. A number of mechanistic studies have been undertaken to elucidate the catalytic pathway. A mono(carbene) complex, (TTP)- OsdCHCO2Et, has been isolated but is not the catalytically active species. An electron- withdrawing ligand trans to the carbene in (TTP)OsdCHCO2Et activates the carbon fragment toward transfer to an olefin. Labeling studies with (TTP)OsdCHX and N2CHY and substrate reactivity profiles are consistent with a trans-osmium(II) bis(carbene) species as the active catalyst. Introduction tained only in rare cases as being a metal-carbene, metal-diazoalkyl, or metal-ylide complex. Due to the On the basis of the volume of publications, one can transient nature of these intermediates, spectroscopic place cyclopropanation of alkenes with diazoalkanes, detection has been achieved in few cases.3 Recent carbon-hydrogen bond insertion, and olefin formation spectroscopic studies of (porphyrinato)rhodium(III)- among the most studied metal-mediated organic trans- catalyzed cyclopropanation reactions provided evidence 1 formations. Although a good understanding of the for the formation of a (porphyrinato)rhodium-diazo- factors influencing the stereochemistry and chemose- alkyl complex when the former complex was treated lectivity has been obtained from systematic studies, the with ethyl diazoacetate at low temperature.4 During the nature of the actual intermediates involved in these course of our work in this area, Simonneaux,5 Che,6 and processes, often called “carbenoids,” is still the subject Nishiyama7 reported evidence for the involvement of of speculation. Most of the above-mentioned transfor- ruthenium carbene complexes in catalytic cyclopropa- mations involve interaction of the diazoalkane reagent nation studies. 2 with the active metal center of the catalyst. The nature In our recent reports we described the efficiency of of the resulting organometallic species has been ascer- osmium(II) porphyrin complexes, such as (TTP)OsLL′ 8 (L ) L′ ) py, 1a;L) py, L′ ) CO, 1b) and [Os(TTP)]2 † Illinois State University. ‡ Universite Louis Pasteur. § Goshen College. (3) (a) Callot, H. J.; Schaeffer, E. J. Chem. Soc., Chem. Commun. | Iowa State University. 1978, 937. (b) Callot, H. J.; Schaeffer, E. New J. Chem. 1980, 4, 311. (1) Key references: (a) Doyle, M. P. Chem. Rev. 1986, 86, 919. (b) (c) Callot, H. J.; Metz, F.; Piechocki, C. Tetrahedron 1982, 38, 2365. Doyle, M. P. Recl. Trav. Chim. Pays-Bas 1991, 110, 305. (c) Tomilov, (d) Collman, J. P.; Rose, E.; Venburg, G. D. J. Chem. Soc., Chem. Yu. V.; Dokichev, V. A.; Dzemilev, U. M.; Nefedov, O. M. Russ. Chem. Commun. 1993, 934. (e) Venburg, G. D. Ph.D. Thesis, Stanford Rev. (Engl. Transl.) 1993, 62, 799. (d) Doyle, M. P. In Catalytic University, 1990. (f) Park, S.-B.; Nishiyama, H.; Itoh, Y.; Itoh, K. J. Asymmetric Synthesis; Ojima, I., Ed.; VCH: New York, 1993; pp 63- Chem. Soc., Chem. Commun. 1994, 1315. (g) Pfeiffer, J.; Nieger, M.; 99. (e) Ye, T.; McKervey, M. A. Chem. Rev. 1994, 94, 1091. Do¨tz, K. H. Eur. J. Org. Chem. 1998, 1011, 1. (h) Straub, B. F.; (2) For examples using rhodium, see: (a) Doyle, M. P.; Bagheri, V.; Hofmann, P. Angew. Chem., Int. Ed. 2001, 40, 1288. Wandless, T. J.; Harn, N. K.; Brinker, D. A.; Eagle, C. T.; Loh, L.-L. J. (4) (a) Maxwell, J.; Kodadek, T. Organometallics 1991, 10,4.(b) Am. Chem. Soc. 1990, 112, 1906. (b) Maxwell, J. L.; O’Malley, S.; Maxwell, J. L.; Brown, K. C.; Bartley, D.; Kodadek, T. Science 1992, Brown, K. C.; Kodadek, T. Organometallics 1992, 11, 645. (c) Doyle, 256, 1544. (c) O’Malley, S.; Kodadek, T. Organometallics 1992, 11, M. P.; Zhou, Q.-L.; Simonson, S. H.; Lynch, V. Synlett 1996, 697. (d) 2299. (d) Bartley, D. W.; Kodadek, T. J. Am. Chem. Soc. 1993, 115, Davies, H. M. L.; Bruzinski, P. R.; Lake, D. H.; Kong, N.; Fall, M. J. J. 1656. Am. Chem. Soc. 1996, 118, 6897. For examples using copper, see: (e) (5) Galardon, E.; Le Maux, P.; Simonneaux, G. Tetrahedron 2000, Fritschi, H.; Leutenegger, U.; Phaltz, A. Helv. Chim. Acta 1988, 71, 56, 615. 1553. (f) Pe´rez, P. J.; Brookhart, M.; Templeton, J. L. Organometallics (6) Che, C.-M.; Huang, J.-S.; Lee, F.-W.; Li, Y.; Lai, T.-S.; Kwong, 1993, 12, 261. (g) Bedekar, A. V.; Andersson, P. G. Tetrahedron Lett. H.-L.; Teng, P.-F.; Lee, W.-S.; Lo, W.-C.; Peng, S.-M.; Zhou, Z.-Y. J. 1996, 27, 4073. For examples using other metals, see: (h) Fukuda, T.; Am. Chem. Soc. 2001, 123, 4119. Katsuki, T. Synlett 1995, 825. (i) Nishiyawa, H.; Itoh, Y.; Sugawara, (7) Park, S.-B.; Sakata, N.; Nishiyama, H. Chem. Eur. J. 1996, 2, Y.; Matsumoto, H.; Aoki, K.; Itoh, K. Bull. Chem. Soc. Jpn. 1995, 68, 303. 1247. (j) Navarro, R.; Urriolabeitia, E. P.; Cativiela, C.; Diaz-de- (8) Abbreviations used: TTP ) dianion of meso-tetra-p-tolylporphy- Villegas, M. D.; Lo´pez, M. P.; Alonso, E. J. Mol. Catal. A: Chem. 1996, rin; py ) pyridine; THF ) tetrahydrofuran; EDA ) ethyl diazoacetate; 105, 111. (k) Fukada, T.; Katsuki, T. Tetrahedron 1997, 53, 7201. Mes ) 1,3,5-trimethylphenyl; Por ) generic porphyrinato dianion. 10.1021/om010787h CCC: $20.00 © 2001 American Chemical Society Publication on Web 10/26/2001 5190 Organometallics, Vol. 20, No. 24, 2001 Hamaker et al. (2), and iron (II) porphyrin complexes, Fe(TTP) (3), for similar to the preparation of other diazo reagents.2a Propyl the catalysis of olefin formation from diazoalkanes and acetoacetate was made by acetoacetylation of 1-propanol with for the stereoselective cyclopropanation of alkenes with 2,2,6-trimethyl-4H-1,3-dioxin-4-one (diketene-acetone adduct) 16 diazoalkanes.9 We demonstrated that neutral mono- in refluxing xylenes. A literature procedure was used in the preparation of trans-â-deuteriostyrene.17 Bis[(5,10,15,20-tetra- (alkylidene) species form upon treatment of [Os(TTP)]2 p-tolylporphyrinato)osmium(II)], [Os(TTP)]2, was prepared by diazoalkanes. Two examples of these mono(alkyli- from (TTP)Os(py) , according to a published procedure.18 The dene) complexes have been characterized by X-ray 2 bis(pyridine) complex, (TTP)Os(py)2, was prepared from either 10 19 crystallography. These isolable mono(alkylidene) com- (TTP)Os(CO)(py) or (TTP)OsO2 by using reported methods. plexes can act as catalysts or stoichiometric reagents Literature procedures were used to prepare (TTP)OsdCHCO2- 9a in cyclopropanation reactions. Preliminary studies Et (4a), (TTP)OsdC(p-tolyl)2 (4b), and (TTP)OsdCHTMS 10 showed that (TTP)OsdCH(CO2Et) (4a), used stoichio- (4c). Authentic samples of ethyl 2-(4-methylphenyl)cyclopro- metrically or catalytically, can promote stereoselectively panecarboxylic acid ester (5d) and ethyl 2-(4-(trifluoromethyl)- the cyclopropanation of styrene, giving similar yields phenyl)cyclopropanecarboxylic acid ester (5f) were gifts from of products in both cases. However, mono(alkylidene) Thomas Kodadek of the University of Texas at Austin. d complexes react slowly with alkenes compared to the (TTP)Os CH(Mes) (4d).
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