Note pubs.acs.org/Organometallics
Chromium-Templated Benzannulation of (η5-Cyclohexadienyl) Mn(CO)3-Methoxy-Cr(CO)5 Carbenes Julien Dubarle-Offner,† Françoise Rose-Munch,† Karl-Heinz Dötz,*,‡ Eric Rose,*,† Anne Sophie Cuvier,† and Armen Panossian† †
UPMC Univ Paris06, IPCM Institut Parisien de Chimie Moléculaire, CNRS UMR 7201, Equipe Chimie Organique et Organométallique, Bâtiment F, Porte 239, Case 181, 4 Place Jussieu, F-75005 Paris Cedex 05, France ‡ Kekulé-Institut für Organische Chemie und Biochimie, Rheinische Friedrich-Wilhelms Universität Bonn, Gerhard-Domagk-Strasse 1, D-52121 Bonn, Germany S Supporting Information *
ABSTRACT: Pentacarbonyl{methoxy-[1-(η5-4-methoxy-6phenylcyclohexadienyl)tricarbonylmanganese]carbene}chromium (5) accessible from (η 5 -1-bromo-4-methoxy-6-phenylcyclohexadienyl)tricarbonylmanganese (4) and Cr(CO) 6 undergoes a chromiumtemplated benzannulation with 3-hexyne to give monometallic Cr complex 12 in 60% yield. The key feature of this reaction is the participation of a conjugated double bond of the η5-cyclohexadienyl-Mn moiety in the [3+2+1] benzannulation reaction. The Xray structure of complex 12 reveals a syn position of the phenyl group with respect to the Cr tripod, supporting the participation of the Mn moiety in the benzannulation process.
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of hydride to the C2 carbon of the π-system of the starting material (Scheme 1).
INTRODUCTION
The tricarbonylchromium and -manganese entities M(CO)3 (M = Cr, Mn+) easily coordinate arene rings to form η6-arene complexes. The electrophilic nature of the tripod makes the arene electron-deficient and effects an “Umpolung”, and that reverses the reactivity of free arenes. The (η 6-arene)Cr(CO)3 complexes1 have been widely studied, and their applications investigated, in contrast to the cationic manganese derivatives, 2 which are far more electrophilic than the neutral chromium analogues. Despite these features, η6-Mn complexes have received much less attention because the synthetic routes to functionalize their derivatives are not as easy as those for analogous η6-Cr complexes. A direct functionalization method involving ipso nucleophilic substitution of η6-halogenoarene Mn complexes is limited to oxygen-, sulfur-, and nitrogencontaining nucleophiles.2a,c Furthermore, the lack of solubility of these very polar cationic complexes in usual organic solvents inhibits their purification by column chromatography. For these reasons, in the past few years the study of the chemistry of (η 5cyclohexadienyl)Mn(CO)3 complexes has been emerging. They are soluble in most commonly used organic solvents and easily purified by silica gel chromatography column.2i,j Their easy preparation permits the discovery of new methods of functionalization involving Pd cross-coupling, 3 lithiation reactions,4 and indirect nucleophilic cine and tele substitutions5 in contrast to direct ipso SNAr.2a,c,6 This has greatly expanded the scope of the (η5-cyclohexadienyl)Mn(CO)3 complexes, allowing to substitute the η5-π-system by different groups such as keto functions.7 Thus, when ketone 1 reacted with hydrides, the two η5-diastereoisomeric alcohols 2 were recovered as well as a third compound, 3, due to the unexpected exo-1,4-addition © 2011 American Chemical Society
Scheme 1. Addition of Hydride to (η5Cyclohexadienyl)Mn(CO)3 Complexes
This experiment shed light on the particular reactivity of a πbond conjugated to an electron-withdrawing group at the end of the η5 π-system toward the addition of a nucleophile. Another example of the special reactivity involved in a π system was reported in the Dötz reaction in the case of a conjugated double bond of a phenyl group.8 Thus, after having worked with the Bonn group on the synthesis of heterobimetallic complexes, benzannulation, and haptotropic migration,9 we extended our collaboration by reporting now the synthesis and the reactivity of [(η5-cyclohexadienyl)Mn(CO)3(methoxy)carbene]Cr(CO)5 complexes toward diethylacetylene.
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RESULTS AND DISCUSSION
A solution of (η5-1-bromo-4-methoxy-6phenylcyclohexadienyl)Mn(CO) 3 complexes 410 in THF reacted with n-butyllithium at −78 °C to deliver the corresponding lithiated species through a lithium/bromide Received: September 30, 2011 Published: November 28, 2011 6778
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exchange reaction, which can be trapped with Cr(CO) 611 followed by O-alkylation of the acyl metalate formed in situ with methyltriflate MeSO3CF3.9 The heterobimetallic Cr−Mn complex 5 was formed in 28% yield as the major product
Scheme 3. Formation of Complex 6
Scheme 2. Preparation of Fischer-Type Carbenes
3). Similarly, if the reaction is not performed strictly at −78 °C, lithiation at the C3 carbon, ortho to the OMe group, occurs to afford complexes 7 and 8 (Scheme 2). The most important goal to reach was to find out whether a [3+2+1] benzannulation reaction could occur and whether the two tricarbonylmetal entities would stay coordinated (see 11) to the two final adjacent rings. Thus, complex 5 and diethylacetylene were warmed to 65 °C for 2 h, and the reaction mixture was trapped with tert-butyldimethylsilyltriflate
(Scheme 2). Selected 1H NMR data of carbene 5 are worth noting; indeed, the H2 proton for example resonates at a high frequency of 6.32 ppm. This proton is more deshielded than the H3 proton at 5.86 ppm, as is usually the case of η5-Mn complexes substituted by electron-withdrawing groups such as ketones7 (Scheme 1).
Scheme 4. Benzannulation of Carbene 5
CMe3CMe2SO3CF3 and NEt3 (Scheme 4). The 1H NMR spectrum of the crude mixture no longer exhibits a η5-Mn fingerprint but shows an olefinic proton at 4.15 ppm. Furthermore, the 13C NMR spectrum indicates the presence of a Cr(CO)3 entity at 236.2 ppm and the absence of a Mn(CO)3 entity. Indeed, the resonance at 222.50 ppm characteristic for Mn(CO)3 in 5 has disappeared. In addition, IR spectroscopy revealed the disappearance of the Mn(CO) 3 band at 2023 cm−1 and the appearance of Cr(CO)3 absorptions at 1944 and 1860 cm−1. Thus, these data are in good agreement with an η6-Cr organometallic moiety. After chromatography on silica gel followed by crystallization, complex 12 was isolated in 60% yield. Its structure was confirmed by mass spectroscopy and by an X-ray structure determination. Crystallization of the monometallic complex 12 gave nice crystals suitable for an X-ray analysis (Figure 2). This structure shows that the arene ring is coordinated to the Cr(CO)3 tripod. The other carbocycle contains a C5−C6 single bond and a C7C8 double bond as an enol ether. The phenyl substituent is located at the same face as the Cr(CO)3 tripod at the adjacent arene ring. The conformation of the Cr(CO)3 tripod is not staggered14 but almost eclipsed with respect to the OMe group.15 A mechanism explaining the formation of complex 12 is suggested in Scheme 5, taking into account the steps previously elucidated for the benzannulation of pentacarbonyl[(methoxy)phenylcarbene]chromium.8,16 Decarbonylation of carbene complex 5 followed by coordination of the alkyne is suggested to afford the cis alkyne-carbene intermediate 13. This step involves an adequate position in 14trans of the Cr(CO)3 tripod in the opposite site with respect to the Mn(CO)3 tripod to avoid steric hindrance between the two organometallic parts in the case of 14cis
Figure 1. Molecular structure of complex 5 with thermal ellipsoids at the 50% probability level. Selected bond lengths (Å): Mn−C1 2.260(2), Mn−C2 2.145(2), Mn−C3 2.182(2), Mn−C4 2.230(2), Mn−C5 2.184(2), Cr−C7 2.095(2)(2), C1−C7 1.497(2), C1−C6 1.546(2), C5−C6 1.521(2), C5−C4 1.412(2), C3−C4 1.433(2), C2− C3 1.429(2), C2−C1 1.422(2).
Crystallization of complex 5 gave crystals suitable for an Xray analysis. An ORTEP view is presented in Figure 1. The η5-cyclohexadienyl moiety exhibits the classical coplanar five-carbon geometry C1, C2, C3, C4, C5 with carbon C6 lying out of this plane pointing away from the metal fragment. The Mn−C bond lengths range from 2.145 to 2.260 Å. The Mn− C1 distance represents the longest Mn−C bond and the Mn− C2 distance the shortest (2.145 Å), which can be compared favorably with that of complex 1 (2.119 Å), bearing a ketone at the C1 carbon.7 The sp3 C6 carbon is eclipsed by one of the Mn−CO bonds, in agreement with what is observed in η5-Mn complexes.12 The dihedral angle between the C1, C2, C3, C4, C5 and C1, C6, C5 planes is 41.8(1)°. Byproducts can be sometimes obtained.13 Indeed, the debrominated complex 9b (Scheme 3) as well as complexes 6, 7, and 8 can be recovered as byproducts in 0.5−5% yield each (Scheme 2). Indeed, if residual water molecules are present, 9b is formed and corresponds to the hydrolysis of 9a, and if THF was not completely removed, compound 6, another chromium carbene, was obtained. Its formation can be interpreted by trapping the lithiated η5-Mn complex 9a by Cr(CO)6, giving the anionic species 10, which is trapped by residual tetrahydrofuran methylated by MeSO3CF3 (Scheme 6779
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hexadienyl ligand coordinated to Mn(CO)3 similar to a π-bond of the phenyl group of pentacarbonyl[(methoxy)phenylcarbene]chromium in the traditional Dötz reaction. This affords the enol ether of the dihydronaphthalene-Cr(CO) 3 complex 12. The synthesis of dihydronapthalene derivatives from anisole in a four-step sequence is unprecedented, although the yield is not entirely satisfying. More interestingly, from a mechanistic point of view, this study reveals the crucial role of a double bond of an η 5 -methoxycyclohexadienylMn(CO) 3 complex conjugated to an electron-withdrawing group, which can be considered as an η2:η3 system and used in a [3+2+1] benzannulation reaction.
Figure 2. Molecular structure of complex 12 with thermal ellipsoids at the 50% probability level. Selected bond lengths (Å): Cr−C1 2.269(2), Cr−C2 2.2536(19), Cr−C3 2.2344(19), Cr−C4 2.2142(19), Cr−C4A 2.2271(18), Cr−C8A 2.269(2), C1−C2 1.415(3), C2−C3 1.339(3), C3−C4 1.431(3), C4−C4A 1.403(2), C4A-C5 1.522(2), C5−C6 1.534(2), C6−C7 1.484(3), C7−C8 1.329(2), C8−C8A 1.459(3), C4A−C8A 1.431(3), C1−C8A 1.406(2).
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EXPERIMENTAL SECTION
General Considerations. All experiments involving organometallic compounds were carried out under inert nitrogen atmosphere by using standard Shlenk techniques. Solvents for reactions were distilled, dried, and saturated with nitrogen using standard methods just before use. Chromatographic columns were prepared with Carl Roth GmbH silica gel 60 (0.02−0.045 mm). 1H and 13C NMR spectra were recorded on Brüker ARX 200 MHz and Avance 400 MHz spectrometers at room temperature. IR spectra were measured with a Brüker tensor 27 spectrometer. Mass spectra were recorded by the Groupe de Spectrométrie de Masse, UMR 7201, UPMC. Synthesis of 5. Tricarbonyl(6-exo-phenyl-η 5 -1-bromo-4methoxycyclohexadienyl)manganese complex 49 (3.97 g, 9.85 mmol) is dissolved in 10 mL of freshly distilled absolute THF, giving a yellow solution. At −78 °C n-BuLi, a 1.6 M solution in hexane (4.4 mL, 7.04 mmol), is added drop by drop; the solution becomes immediately brown, and 5 min later Cr(CO)6 (2.64 g, 12.0 mmol) is added. The solution is allowed to reach 20 °C within an hour, and then the solvent is evaporated via a vacuum pump for 2 h. The resulting brown oil is then dissolved in 10 mL of dry CH2Cl2 and cooled to −50 °C. Methyltriflate (3.28 g, 20.0 mmol) is added drop by drop to the solution, which is then warmed to room temperature within half an hour and stirred for an extra hour. The solution becomes deep dark red. The reaction mixture dissolved in CH2Cl2 is added to 2 g of silica gel and evaporated under reduced pressure to afford a dry, colored powder, which is added on top of a silica gel chromatography column. Distilled solvents are used to elute the products. Elution with petroleum ether/dichloromethane (4:1) affords small amounts of complex 9b4 (0.5−5% yield), complex 5 as an air-sensitive, dark red powder, and then small amounts of complexes 7 and then 6 and 8 (0.5−5% each, depending of the experimental conditions). 13 Crystallization of 5 from CH2Cl2 at 4 °C gave red crystals (1.540 g, 28%) suitable for X-ray analysis. IR (neat) (cm−1): 2057 Cr(CO)5, 2023 (s) Mn(CO)3, 1951 (vs) Cr(CO)5, 1909 (m) Mn(CO)3 cm−1. 1 H NMR (200 MHz, CDCl3) δ (ppm): 3.60 (3H, s, OCH3), 3.75 (1H, dd, 3J 3 and 7 Hz, H5), 4.76 (1H, dd, 3J 7 Hz, H6), 4.86 (3H, s, carbene OCH3), 5.86 (1H, dd, 3J 3 and 7 Hz, H3), 6.32 (1H, dd, 3J 2 and 7 Hz, H2), 6.78 (2H, d, J 7 Hz, ArH, 7.15 (m, 3H, ArH). 13C NMR (100 MHz, CDCl3): δ (ppm): 40.74 (C6), 44.47 (C5), 55.19 (OMe), 66.54 (OMe carbene), 73.00 (C3), 80.52 (C1), 100.00 (C2), 128.60, 127.11, 125.24 (Ph), 144.70 (C4), 145.80 (Ph), 216.62 (Cr(CO)5), 222.50 (Mn(CO)3). 338.64 (CCr). HRMS (ESI): m/z [M + O − Cr(CO)5 + Na]+ calculated for the oxidative demetalation product C18H15O6MnNa, 405.0141; found, 405.0144. Anal. Calcd for C23H15CrMnO10: C 49.48, H 2.71. Found: C 49.31, H 2.58. Synthesis of 12. A solution of tricarbonyl[6-exo-phenyl-η5-1(pentacarbonyl(methoxy)carbene)chromium-4methoxycyclohexadienyl]manganese (5) (1.80 g, 3.2 mmol) and 3hexyne (1.02 g, 13.1 mmol) in 35 mL of tert-butyl methyl ether was warmed to 65 °C (oil bath temperature) for 2 h. Then the phenolic group was protected at room temperature by addition of triethylamine (0.56 mL, 6.2 mmol) and tert-butyldimethylsilyl triflate (1.43 mL, 6.2 mmol). After stirring for 1.5 h, chromatography on silica gel with petroleum ether/dichloromethane (1:1) afforded complex 12 as an airsensitive red powder. The different fractions are recovered under N 2
Scheme 5. Suggested Mechanism for the Benzannulation
(Scheme 5). The η3-Mn complex 14trans could be transformed into the η3- or η1-Mn complex 15, which could add a proton to give a cationic [MnIII−H]+ intermediate η1 16 or η3 17. Hydride migration and decoordination of [Mn(CO)3]+ could yield a zwitterionic intermediate O−M+ or neutral compound OM (M = Mn(CO)3) 18 and then complex 12. An important feature should be underlined: the phenyl group at the C5 carbon and the chromium moiety are syn with respect to the 5,6-dihydronaphthalene unit, as shown, vide supra, by the X-ray structure of 12. As the phenyl group is anti to the Mn(CO)3 tripod because addition of a nucleophile to an η6-Mn occurs anti to the Mn(CO)3, this implies that the Mn and Cr units are coordinated in an anti fashion at the cyclization step of 14trans giving 15. In summary, the preparation of an unprecedented bimetallic [(η5-cyclohexadienylMn(CO) 3)methoxycarbene] Cr(CO) 5 complex (5) is reported and its structure determined. A benzannulation reaction has been realized using heterobimetallic carbene 5 and diethylacetylene, which involves the participation of a conjugated double bond of an η5-cyclo6780
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and concentrated under a N2 stream. Crystallization from dichloromethane and crystallization from diethyl ether at 4 °C under N2 gave pale orange crystals of complex 12 (1.13 g, 1.92 mmol, 60%) suitable for X-ray analysis. 1H NMR (400 MHz, CDCl3): δ (ppm) 0.44 (3H, s, SiCH3), 0.48 (3H, s, SiCH3), 1.07 (9H, s, SiC(CH3)3), 1.19 (3H, t, J 7 Hz, CH2CH3), 1.26 (3H, t, J 7 Hz, CH2CH3), 2.45 (4H, m, CH2CH3), 2.81 (2H, m, H5), 3.38 (3H, s, OMe), 3.78 (3H, s, OMe), 4.15 (1H, m, H6), 5.58 (1H, s, H3), 7.40 (5H, m, Ph). 13C NMR (100 MHz, CDCl3): δ (ppm) −2.1, −1.3 (Si(CH3)2), 14.9 (CH3), 17.2 (CH3), 18.2 (SiC), 19.5 (CH2), 20.6 (CH2), 26.7 (SiC(CH3)3), 37.0, 41.8 (C5, C6), 56.7 (OCH3), 62.5 (OCH3ArCr), 89.4 (C8), 99.3, 104.1, 106.5, 111.7, 122.2 (ArCr), 127.4, 128.7, 129.0 (Ph), 139.9 (ArCr), 145.7 (Ph), 163.7 (C7), 236.2 (Cr(CO)3). IR (film): ν (cm−1) 2934, 2859, 2360, 1944, 1860, 1644, 1263. ESI: m/z [M + Na]+ for C31H40CrO6SiNa calcd 611.1897, found 611.1892, corresponding to [M + Na]+. Anal. Calcd for C31H40CrO6Si: C 63.24, H 6.85. Found: C 63.01, H 6.71.
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tricarbonylmanganese complexes: synthesis and reactivity. Patai’s Chemistry of Functional Groups. The Chemistry of Organomanganese Compounds Marek, I.; Rappoport, Z., Eds.; J. Wiley & Sons Ltd.: New York, 2011; pp 489−558. (j) Rose-Munch, F.; Rose, E. Org. Biomol. Chem. 2011, 9, 4725. (3) Auffrant, A.; Prim, D.; Rose-Munch, F.; Rose, E.; Schouteeten, S.; Vaissermann, J. Organometallics 2003, 22, 1898. (4) Jacques, B.; Chavarot, M.; Rose-Munch, F.; Rose, E. Angew. Chem., Int. Ed. 2006, 45, 3481. (5) (a) Balssa, F.; Gagliardini, V.; Rose-Munch, F.; Rose, E. Organometallics 1996, 15, 4373. For Cr complexes, see: (b) Boutonnet, J. C.; Rose-Munch, F.; Rose, E. Tetrahedron Lett. 1985, 26, 3989. (c) Rose-Munch, F.; Rose, E.; Semra, A. J. Chem. Soc., Chem. Commun. 1986, 1551. (d) Rose-Munch, F.; Rose, E.; Semra, A. J. Chem. Soc., Chem. Commun. 1987, 942. (e) Rose-Munch, F.; Rose, E.; Semra, A.; Bois, C. J. Organomet. Chem. 1989, 363, 103. (f) Djukic, J.-P.; Rose-Munch, F.; Rose, E. Organometallics 1995, 14, 2027. (6) For Cr complexes, ipso SNAr: (a) Boutonnet, J. C.; Rose-Munch, F.; Rose, E.; Semra, A. Bull. Soc. Chim. Fr. 1987, 640. (b) Rose-Munch, F.; Rose, E.; Semra, A.; Garcia-Oricain, J.; Knobler, C. J. Organomet. Chem. 1989, 363, 297. (c) Rose-Munch, F.; Aniss, K.; Rose, E.; Vaisserman, J. J. Organomet. Chem. 1991, 415, 223. (7) Eloi, A.; Rose-Munch, F.; Jonathan, D.; Tranchier, J. F.; Rose, E. Organometallics 2006, 25, 4554. (8) (a) Dötz, K. H. Angew. Chem., Int. Ed. Engl. 1975, 14, 644. (b) Dötz, K. H.; Tomuschat, P. Chem. Soc. Rev. 1999, 28, 187. (c) Dötz, K. H.; Stendel, J., Jr. In Modern Arene Chemistry; Astruc, D., Ed.; Wiley-VCH: Weinheim, 2002; pp 250−296. (d) Minatti, A.; Dötz, K. H. Top. Organomet. Chem. 2004, 13, 123. (e) Waters, M. L.; Wulff, W. D. Org. React. 2008, 70, 121. (f) Dötz, K.-H.; Stendel, J. Chem. Rev. 2009, 109, 3227. (9) (a) Dubarle Offner, J.; Fröhlich, R.; Rose-Munch, F.; Rose, E.; Dötz, K. H. Organometallics 2009, 28, 3004. (b) Dubarle Offner, J.; Schnakenburg, G.; Rose-Munch, F.; Rose, E.; Dö t z, K. H. Organometallics 2010, 29, 3308. (c) Dubarle Offner, J.; Schnakenburg, G.; Rose-Munch, F.; Rose, E.; Dötz, K. H. Inorg. Chem. 2011, 50, 8153. (10) (a) Eloi, A.; Rose-Munch, F.; Rose, E.; Lennartz, P. Organometallics 2009, 28, 5757. (b) Rose-Munch, F.; Cetiner, D.; Chavarot-Kerlidou, M.; Rose, E.; Agbossou-Niedercorn, F.; Chamoreau, L M.; Gontard, G. Organometallics 2011, 30, 3530. (c) Eloi, A.; Poizat, M.; Hautecoeur, A.; Panossian, M.; Rose-Munch, F.; Rose, E. Organometallics 2011, 30, 5564. (11) (a) Fischer, E. O.; Maasboel, A. Angew. Chem. 1964, 76, 644. (b) Fischer, E. O. Auf dem Weg zu Carben- und Carbin-Komplexen (Nobel Lecture) Angew. Chem. 1974, 86, 651. (12) (a) Eloi, A.; Rose-Munch, F.; Rose, E.; Chavarot-Kerlidou, M.; Gérard, H. Organometallics 2009, 28, 925. (b) Eloi, A.; Rose-Munch, F.; Rose, E. J. Am. Chem. Soc. 2009, 131, 14178. (c) Cetiner, D.; Tranchier, J. J. P.; Norel, L.; Rose-Munch, F.; Rose, E.; Herson, P. Organometallics 2010, 29, 1778. (d) Eloi, A.; Rose-Munch, F.; Rose, E.; Pille, A.; Lesot, P. Organometallics 2010, 29, 3876. (e) Rose-Munch, F.; Cetiner, D.; Chavarot-Kerlidou, M.; Rose, E. New J. Chem. 2011, 35, 2004. (f) Rose, E.; Dubarle-Offner, J.; Rose-Munch, F.; Gérard, H. New J. Chem. 2011, 35, 2375. (13) The yield of byproducts is sensitive to the ability of the students to perform the reaction with care. (14) (a) Boutonnet, J. C.; Levisalles, J.; Rose, E.; Precigoux, G.; Courseille, C.; Platzer, N. J. Organomet. Chem. 1983, 255, 317. (b) Boutonnet, J. C.; Levisalles, J.; Rose-Munch, F.; Rose, E. J. Organomet. Chem. 1985, 290, 153. (15) Boutonnet, J. C.; Rose-Munch, F.; Rose, E.; Jeannin, Y.; Robert, F. J. Organomet. Chem. 1985, 290, 185. (16) (a) Gleichmann, M. M.; Dötz, K. H.; Hess, B. A. J. Am. Chem. Soc. 1996, 118, 10551. (b) Torrent, M.; Duran, M.; Sola, M. Organometallics 1998, 17, 1492. (c) Fischer, H.; Hofmann, P. Organometallics 1999, 18, 2590.
ASSOCIATED CONTENT
S Supporting Information *
CIF files giving crystallographic data for complexes 5 and 12; tables showing crystal data and refinement details and synthesis of complexes 6−8. This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author *E-mail:
[email protected] (E.R.);
[email protected] (K.H.D.).
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ACKNOWLEDGMENTS CNRS is acknowledged for a grant for J.D.O. and for financial support to F.R.M. and E.R. We thank H. Rousselière for determination of the structures of complexes 5 and 12.
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REFERENCES
(1) (a) Jaouen, G. Pure Appl. Chem. 1986, 58, 597. (b) Djukic, J. P.; Rose-Munch, F.; Rose, E.; Dromzee, Y. J. Am. Chem. Soc. 1993, 115, 6434. (c) Semmelhack, M. F. In Comprehensive Organometallic Chemistry II, Vol. 2.4; Wilkinson, G.; Abel, E. W.; Stone, F. G. A., Eds.; Pergamon Press: Oxford, UK, 1995; p 517. (d) Rose-Munch, F.; Rose, E. In Modern Arene Chemistry; Astruc, D., Ed.; Wiley-VCH, Chapter 11, 2002; pp 368−399. (e) Rose-Munch, F.; Rose, E. Eur. J. Inorg. Chem. 2002, 1269. (f) Kündig, E. P. Topics in Organometallic Chemistry; Springer: Berlin, 2004; Vol. 7. (g) Uemura, M. Top. Organomet. Chem. 2004, 7, 129. (h) Prim, D.; Andrioletti, B.; RoseMunch, F.; Rose, E.; Couty, F. Tetrahedron 2004, 60, 3325. (i) Rosillo, M.; Domínguez, G.; Pérez-Castells, J. Chem. Soc. Rev. 2007, 36, 1589. (j) Astruc, D. Organometallic Chemistry and Catalysis; Springer: Heidelberg, 2007; p 490. (2) (a) Pauson, P. L.; Segal, J. A. J. Chem. Soc., Dalton Trans. 1975, 1677. (b) Treichel, P. M. Manganese Group, in Comprehensive Organometallic Chemistry Abel, E. W.; Stone, F. G. A.; Wilkinson, G., Eds.; Pergamon Press: Oxford, 1982; Vol. 4, Chapter 29, pp 1−159. (c) Pearson, A. J.; Bruhn, P. R. J. Org. Chem. 1991, 56, 7092. (d) McDaniel, K. F. In Comprehensive Organometallic Chemistry II, Vol. 6; Abel, E. W.; Stone, F. G. A.; Wilkinson, G., Eds.; Pergamon Press: Oxford, 1995; pp 93−107. (e) Giner Planas, J.; Prim, D.; Rose-Munch, F.; Rose, E.; Monchaud, D.; Lacour, J. Organometallics 2001, 20, 4107. (f) Kündig, E. P.; Pape, A. Top. Organomet. Chem. 2004, 7, 71. (g) Sweigart, D. A.; Rheingold, J. A. In Encyclopedia of Inorganic Chemistry, 2nd ed.; Lukehart, C. M., Ed.; Wiley: New York, 2005; p 2907. (h) Sweigart, D. A.; Reingold, J. A.; Son, S. U. Manganese Compounds with CO Ligands. In Comprehensive Organometallic Chemistry III, Vol. 5; Crabtree, R. H.; Mingos, D. M. P., Eds.; Elsevier Science Ltd: Oxford, 2006; pp 761−813. (i) Rose-Munch, F.; Rose, E.; Eloi, A. Cationic (η6-arene) and neutral (η5-cyclohexadienyl) 6781
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