Chemistry and catalysis advances in organometallic chemistry and catalysis
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169 Zr Cl Cl Si Zr Cl Cl Zr Cl Cl Si Si – CH
2 =CH
2 Ru-I or Ru-II Scheme 12.28 R Me + Cat. = [Mo(CO) 6 ]/XC
6 H 4 OH cat.
Me – Me
Me Fe R Fe Scheme 12.29 R = Fc, Ph, n-C 6 H 13 , CH 2 CH 2 OAc, 4-R -C 6 H
(R = Me, MeO, Ph, Ac, CF 3 , CN); X
= F, Cl. cat.
Me – Me
Cat. = [Mo(CO) 6 ]/ClC 6 H 4 OH Me R 2 R 2 R 2 R 2 R 1 R 1 R 1 R 1 R 1 Ru R 1 R 1 R 1 R 1 R 1 Ru R 2 R 2 R 2 R 2 R 2 R 2 R 2 R 2 R 1 R 1 R 1 R 1 R 1 Ru 2 Scheme 12.30 R 1 , R 2 = H, Me. 12.5 CONCLUSIONS AND OUTLOOK Olefin metathesis reaction catalyzed by well-defined metal (mainly ruthenium and molybdenum) carbene complexes is increasingly being applied in organic and organometallic synthesis [37]. Ruthenium, molybdenum, and tungsten carbene complexes appeared to be widely compatible with functional groups present in metallocenes. The application of these complexes as catalysts for olefin metathesis in metal coordination spheres resulted in the synthesis of a considerable number of novel metallocene derivatives. This methodology appeared to be compatible even with the very sensitive metallocenes functional groups such as nickelocene or the group 4 bent metallocenes. In this review, we have shown that olefin metathesis has been successfully used to synthesize derivatives of 18 VE ferrocenes, ruthenocenes, 20 VE nickelocenes, and 16 VE group 4 bent metallocene dichlorides. This method has also been used for the preparation of polymers bearing metallocenes as parts of the polymer chain or side groups. We consider this method as a major advantage in synthetic organometallic chemistry that will probably open up a variety of entries to novel metallocene derivatives. Further development in this field depends on possibilities of practical applications of these products, for example, as components of active catalytic systems or ligands. REFERENCES 1. Ivin, K. J.; Mol, J. C. Olefin Metathesis and Metathesis Polymerization; Academic Press: San Diego, 1997. 2. Bauer, E. B.; G ł adysz, J. A. In Handbook of Metathesis; Grubbs, R. H., Ed.; Wiley-VCH Verlag GmbH: Weinheim, Germany, 2003; Vol. 2 ; Chapter 2.11. 3. Albagli, D.; Bazan, G.; Wrighton, M. S.; Schrock, R. R. J. Am. Chem. Soc. 1992, 114 , 4150. 4. Watson, K. J.; Zhu, J.; Nguyen, S. T.; Mirkin, C. A.. J. Am. Chem. Soc. 1999, 121 , 462. 5. Ren, L.; Zhang, J.; Hardy, C. G.; Ma, S.; Tang, C. Macromol. Rapid Commun. 2012, 33 , 510. 6. Stanton, C. E.; Lee, T. R.; Grubbs, R. H.; Lewis, N. S.; Pudelski, J. K.; Callstrom, M. R.; Erickson, M. S.; McLaughlin, M. L.
7. Heo, R. W.; Somoza, F. B.; Lee, T. R. J. Am. Chem. Soc. 1998, 120 , 1621. 8. Buretea, M. A.; Tilley, T. D. Organometallics 1997, 16 , 1507. 9. Arisandy, C.; Cowley, A. R.; Barlow, S. J. Organomet. Chem. 2004, 689 , 775. 10. Gamble, A. S.; Patton, J. T.; Boncella, J. M. Macromol. Chem. Rapid Commun. 1993, 13 , 109. 11. Weychardt, H.; Plenio, H. Organometallics 2008, 27 , 1479. 170 SYNTHESIS OF METALLOCENES VIA METATHESIS IN METAL COORDINATION SPHERES 12. Garro-H´elion, F.; Guib´e, F. Chem. Commun. 1996, 641. 13. Rutjes, F. P. J. T.; Schoemaker, H. E. Tetrahedron Lett. 1997, 38 , 677. 14. Locke, A. J.; Jones, C.; Richards, C. J. J. Organomet. Chem. 2001, 637–639 , 669. 15. Ogasawara, M.; Nagano, T.; Hayashi, T. J. Am. Chem. Soc. 2002, 124 , 9068. 16. Ogasawara, M.; Nagano, T.; Hayashi, T. Organometallics 2003, 22 , 1174. 17. (a) Ogasawara, M.; Watanabe, S.; Fan, L.; Nakajima, K.; Takahashi, T. Organometallics 2006, 25 , 5201; (b) Ogasawara, M.; Watanabe, S.; Nakajima, K.; Takahashi, T. Pure Appl. Chem. 2008, 80 , 1109. 18. Ogasawara, M.; Watanabe, S.; Nakajima K.; Takahashi, T. J. Am. Chem. Soc. 2010, 132 , 2136. 19. Ogasawara, M.; Watanabe, S.; Nakajima, K.; Takahashi, T. Organometallics 2008, 27 , 6565. 20. Jolly, P. W. Comprehensive Organometallic Chemistry, Vol. 6, Chapter 37.8 ; Pergamon Press: Oxford, 1982. 21. Buchowicz, W.; Jerzykiewicz, L. B.; Krasi´nska, A.; Losi, S.; Pietrzykowski, A.; Zanello, P. Organometallics 2006, 25 , 5076. 22. Seiler, P.; Dunitz, J. D. Acta Crystallogr., Sect. B 1980, 36 , 2255. 23. Vos, D.; Salmon, A.; Sammler, H. -G.; Neumann, B.; Jutzi, P. Organometallics 2000, 19 , 3874. 24. Buchowicz, W.; Furma´nczyk, A.; Zachara, J.; Majchrzak, M. Dalton Trans. 2012, 41 , 9269. 25. H¨uerl¨ander, D.; Kleigrewe, N.; Kehr, G.; Erker, G.; Fr¨ohlich, R. Eur. J. Inorg. Chem. 2002, 2633. 26. Tumay, T. A.; Kehr, G.; Frohlich, R.; Erker, G. Dalton Trans. 2009, 8923. 27. Seshadri, H.; Lovely, C. J. Org. Lett. 2000, 2 , 327. 28. (a) Yasuda, T.; Abe, J.; Iyoda, T.; Kawai, T. Chem. Lett. 2001, 30 , 812; (b) Yasuda, T.; Abe, J.; Yoshida, H.; Iyoda, T.; Kawai, T. Adv. Synth. Catal. 2002, 344 , 705. 29. Kuwabara, J.; Takeuchi, D.; Osakada, K. Organometallics 2005, 24 , 2705. 30. (a) Suzaki, Y.; Osakada, K. Chem. Lett. 2006, 374–375; (b) Suzaki, Y.; Osakada, K. Dalton Trans. 2007, 2376. 31. Ornelas, C.; M´ery, D.; Cloutet, E.; Aranzaes, J. R.; Astruc, D. J. Am. Chem. Soc. 2008, 130 , 1495. 32. (a) Buchowicz, W.; Szmajda, M. Organometallics 2009, 28 , 6838; (b) Buchowicz, W.; Kami´nski, R.; Wo´zniak, K. unpublished results.
33. Sierra, J. C.; H¨uerl¨ander, D.; Hill, M.; Kehr, G.; Erker, G.; Fr¨ohlich, R. Chem. Eur. J. 2003, 9 , 3618. 34. Kuwabara, J.; Takeuchi, D.; Osakada, K. Chem. Commun. 2006, 3815. 35. (a) Kotora, M.; Neˇcas, D.; ˇStˇepniˇcka, P. Collect. Czech. Chem. Commun. 2003, 68 , 1897; (b) Bobula, T.; Hudlick´y, J.; Nov´ak, P.; Gyepes, R.; Cisaˇrov´a, I.; ˇStˇepniˇcka, P.; Kotora, M. Eur. J. Inorg. Chem. 2008, 1 , 3911. 36. (a) Sato, M.; Watanabe, M. Chem. Commun. 2002, 1574; (b) Sato, M.; Kubota, Y.; Kawata, Y.; Fujihara, T.; Unoura, K.; Oyama, A.
37. Grubbs, R. H., Ed. Handbook of Metathesis; Wiley-VCH: Weinheim, Germany, 2003. 13 METAL-MEDIATED [2 + 3] DIPOLAR CYCLOADDITION TO SUBSTRATES WITH CN TRIPLE BOND: RECENT ADVANCES Konstantin V. Luzyanin* and Maxim L. Kuznetsov* Centro de Qu´ımica Estrutural, Instituto Superior T´ecnico, Universidade de Lisboa, Lisboa, Portugal; Department of Chemistry, St. Petersburg State University, St. Petersburg, Russia 13.1 INTRODUCTION Nitriles and isocyanides are among the most versatile organic substrates and are widely employed as starting materials in both industry and laboratory (e.g., for production of amides via hydrolysis of nitriles [1] or application of isocyanides in multicomponent reactions [2–4]). The transformation of these synthons offers an attractive route for the creation of novel C–X (X = C, N, O, and S) bonds, in particular, through reactions of nucleophilic addition or a dipolar cycloaddition (DCA) [1, 3, 5, 6]. The main drawback associated with the reactions of nitriles and isocyanides is their insufficient electrophilic activation (toward nucleophilic addition) or a very moderate dipolarophilicity (toward a DCA). This problem can be successfully overcome by coordination of the substrate to a metal center (Scheme 13.1) [1, 5, 7–9]. Under these conditions, the integration between nitriles (or isocyanides) proceeds at metal centers, giving new species, which, in contrast to metal- catalyzed processes, persist in the coordination state after coupling. In many instances, these metal-mediated processes allow the performance of certain reactions that are not feasible without the involvement of metal, and provide the stabilization of organic species that do not exist in a free state [1, 5–10]. Several types of reactivity for metal-bound nitriles and isocyanides should be recognized [1, 7, 8]. For instance, the nucleophilic addition to metal-bound nitriles allows the generation of imine complexes [1], electrophilic addition produces metal-bound azavinylidenes [1], and the DCA results in coordinated heterocyclic imines (Route I, Scheme 13.1) [5, 6, 10]. With respect to the metal-ligated isocyanides, the addition of nucleophiles furnishes complexes with acyclic aminocarbenes [7, 9, 11], electrophilic addition gives aminocarbynes [8, 12], while the DCA brings about the formation of N-heterocyclic carbene derivatives (Route II, Scheme 13.1) [6, 10]. Among the depicted reactivity modes, we are particularly interested in the reactions of DCA that is accounted as an alternative route for the generation of heterocyclic imines (Route I) and N-heterocyclic carbenes (Route II). While the reactions of the metal-mediated DCA to nitriles have been extensively reviewed circa 10 years ago [1], over the past decade, many new reactions illustrating this approach have appeared. In addition, previously unknown examples for [2 + 3] DCA to isocyanides have emerged. In this survey, we describe the recent trends in metal-mediated transformation of CN substrates via the reactions of [2 + 3] DCA exemplified by the most representative papers. The mechanistic features and driving forces of these processes as well as the reasons of activation effect upon coordination of substrate to the metal center are also discussed. Advances in Organometallic Chemistry and Catalysis: The Silver/Gold Jubilee International Conference on Organometallic Chemistry Celebratory Book, First Edition. Edited by Armando J. L. Pombeiro. © 2014 John Wiley & Sons, Inc. Published 2014 by John Wiley & Sons, Inc.
172 METAL-MEDIATED [2 + 3] DIPOLAR CYCLOADDITION TO SUBSTRATES WITH CN TRIPLE BOND: RECENT ADVANCES Route I Route III [M] N
R 1 C N R 3 R 2 R 4 O O N C R 2 N N N Route IV
Route V [M]
C N R 1 C N R 3 R 2 R 4 O Route II
[M] N C N O C R 2 R 1 [M]
N C N O C R 3 R 1 R 2 R 4 N N N [M]
N N N C N R 1 [M]
C N N N N
Metal-bound isocyanide R 1 [M] C O N C N R 1 R 2 R 4 R 3
Metal-mediated dipolar cycloaddition to nitriles and isocyanides and dipoles employed. (See insert for color representation
+ 3] DIPOLAR CYCLOADDITION TO NITRILES AND ISOCYANIDES: SYNTHETIC STUDIES 13.2.1 Addition of Nitrones and N -Oxides to Nitriles Reported [2 + 3] cycloaddition between acetonitrile ligands in the platinum(IV) complex [PtCl 4 (MeCN) 2 ] and
the aldonitrones R 1 CH =N + (R 2 )O − proceeds at 20–25 ◦ C for 4 h affording 4 -1,2,4-oxadiazoline complexes [PtCl 4
a =C(Me)ON(R 2 )C
H (R 2 )} 2 (N a −C b )] (1) (Route I, Scheme 13.2) as a 1 : 1 mixture of two diastereoisomers [13]. Free 4 -1,2,4-oxadiazolines (2) were liberated almost quantitatively by reaction of the complexes with a slight excess of pyridine (Route II, Scheme 13.2) [13]. In the related studies [14–18], the ligated benzonitriles in the platinum(II) complex [PtCl 2 (PhCN)
2 ] or cis- [PtCl 2
3 MeSO
)(PhCN)] underwent metal-mediated [2 + 3] cycloaddition with nitrones R 1 CH =N + (R 2 )O − to give
4 -1,2,4-oxadiazoline species, [PtCl
2 {N a =C(Ph)N(R 1 )C b H (R 2 )} 2 (N a −C b )] [14, 16] or [PtCl 2 (R
MeSO ) {N a =C(Ph)N(R 1 )C
H (R 2 )} 2 (N a −C b )] [15],
correspondingly. Under
similar conditions, platinum(II) complex
[PtCl 2 (MeCN) 2 ] was reported inactive. Liberation of the free 4 -1,2,4-oxadiazolines was accomplished upon reaction of corresponding complexes with ethane-1,2-diamine (en) [15]. The [2
+ 3] DCA of an acyclic aldonitrone 4-MeC 6 H 4 CH =N + (Me)O
− to nitriles in palladium(II) complex trans- [PdCl 2
2 ] (R = Ph, Me) proceeds at 45 ◦ C (R = Ph) or reflux (R = Me) for 1 day leading to 4 -1,2,4-oxadiazoline complexes [PdCl 2 {N a =C(R)ON(Me)C b H
6 H 4 Me-4 )} 2 (N a −C b )] (3, Scheme 13.3) [19, 20]. The authors found that use of focused microwave irradiation in the place of conventional heating drastically reduces the reaction time. A similar reactivity pattern was demonstrated for platinum(II) and palladium(II) complexes with ( E)-cinnamonitrile [21]. Platinum(II)-bound dialkylcyanamides NCNR 1 2
2 CH =N + (O − )R 3 in the Z-form giving corresponding cycloadducts [22]. By performing a competitive reactivity study of DCA between trans- [PtCl 2
4 CN ) 2 ] (R
4 = Ph and NR 1 2
6 H 4 CH =N + (O − )Me, the authors revealed that both coordinated PhCN and R 1 2 NCN exhibit comparable reactivity. Under similar conditions, alkylnitrile ligands did not react with this dipole. Metal-free 5-NR 1 2
complexes by treatment with excess NaCN [22]. In the related study, the Z-configured nitrones 4-R 2 C
H 4 CH =N + (O − )Me
reacted with the nitrile functionality of the closo-dodecaborate clusters [ nBu
4 N][B
10 H 9 (NCR 1 )] to afford borylated 2,3- dihydro-1,2,4-oxadiazoles [ nBu
4 N][B
10 H 9 {N a =CR 1 ON (Me)C b H (C 6 H 4 R 2 -4 )}(N a −C b )]. This reaction represents the first example of boron-mediated 1,3-DCA of allyl anion type dipoles, that is, nitrones, to the nitrile group.
METAL-MEDIATED [2 + 3] DIPOLAR CYCLOADDITION TO NITRILES AND ISOCYANIDES: SYNTHETIC STUDIES 173 N Pt IV N Cl Cl Cl Cl C Me C Me N Pt IV Cl Cl Cl Cl N R 1 = Ph, C 6 H 4 OH-2, C 6 H 4 Me-4, C
6 H 4 Me-4, C 6 H 4 OMe-4,
C 6 H 4 NO 2 -4, C 6 H 4 NMe
2 -4; R
2 = Me, CH 2 Ph
N R 1 R 2 H O 2 O N O N Me Me R 2 R 1 H R 2 R 1 H N O N Me R 2 R 1 H −[PtCl 4 (py) 2 ] 2py Route I Route II
2 Scheme 13.2 [2 + 3] cycloaddition between MeCN in [PtCl 4 (MeCN)
2 ] and R
1 CH =N + (R 2 )O– [13]. R 1 = Me, Ph Pd Cl Cl N N O H R 1 N 4-MeC 6 H 4 Me H O [PdCl 2 (R 1 CN)
2 ] Me C 6 H 4 Me-4
N N O H R 1 Me 4-MeC
6 H 4 2 3 Scheme 13.3 Palladium(II)-mediated dipolar cycloaddition of nitrones to nitriles [19]. N Ph
2 Ph O N Pt II N Cl Cl C R 1 C R 1 R1 = Et, NMe 2 , NEt 2 , N(C
5 H 10 ) R 2 = Ph, C 6 H 4 Me-4,
C 6 H 4 Cl-4, C
6 H 4 OMe-4 Pt II Cl Cl N N O Ph R 1 R 2 Ph N N O Ph R 1 R 2 Ph
Pt II
Cl N N O Ph R 1 R 2 Ph N C R 1 N Ph R 2 Ph O Route I Route II 4 Scheme 13.4 Dipolar cycloaddition of Ph 2 C
+ (R 2 )O– to nitriles in trans-[PtCl 2 (R 1 CN ) 2 ] [23].
The described [23] reaction between trans-[PtCl 2 (R 1 CN ) 2 ] and the acyclic triaryl ketonitrones Ph 2 C
− (R 2 )O + proceeded as a consecutive two-step intermolecular cycloaddition to give the monocycloaddition products trans- [PtCl 2 (NCR 1 ){N
a =C(R
1 )ON(R
2 )C b Ph 2 }(N a −C b )] (4, Scheme 13.4) and then the bis-2,3-dihydro-1,2,4-oxadiazole com- plexes trans-[PtCl 2 {N
=C(R 1 )ON(R 2 )C b Ph 2 } 2 (N a −C b )] (5) [23]. Ketonitrones Ph 2 C =N − (R 2 )O + were found to be unex- pectedly more reactive toward the platinum(II)-bound nitriles if compared to the related aldonitrones R 3 CH =N + (R 2 )O − . The difference in the reactivity in 1,3-DCA of the keto- and aldonitrones was interpreted by theoretical calculations (see below) [23]. In the other study [24], complexes containing heterocycles of a new type, namely, 2,3a-disubstituted 5,6-dihydro-3aH- [1,3]oxazolo[3,2-b][1,2,4]oxadiazoles (6, Scheme 13.5), were prepared via the intermolecular platinum(II)-mediated DCA between coordinated nitriles in trans/cis-[PtCl 2 (R
CN ) 2 ] and the oxazoline N-oxide C a (Me)
2 CH 2 OC(R 2 ) =N b + (O − )(C
a –N
). With the exception of benzonitrile species, cycloaddition of oxazoline N-oxides to the platinum(II)-ligated nitriles proceeds diastereoselectively giving mixtures of enantiomers. The heterocyclic ligands in 6 were liberated by treatment with excess ethane-1,2-diamine [24]. |
