Selective access to electron donating group substituted (η5-cyclohexadienyl)Mn(CO)3 complexes by bimetallic manganese-palladium activation

Article abstract of DOI:10.1021/om0202773

Unprecedented (η⁵-cyclohexadienyl)Mn(CO)₃ complexes bearing an electron-donating group at the end of the π system have been selectively prepared using Pd catalysis and primary, secondary cyclic, and acyclic amines. This catalytic met

Full text of DOI:10.1021/om0202773

3500
Organometallics 2002, 21, 3500-3502
Selective Access to Electr on Don a tin g Gr ou p Su bstitu ted
(η5-cycloh exa d ien yl)Mn (CO)3 Com p lexes by Bim eta llic
Ma n ga n ese-P a lla d iu m Activa tion
Audrey Auffrant, Damien Prim,† Franc¸oise Rose-Munch,* and Eric Rose*
Laboratoire de Synthe`se Organique et Organome´tallique, UMR CNRS 7611, Universite´ Pierre
et Marie Curie, Tour 44 1er e´tage, 4 place J ussieu, BP 181, 75252 Paris Cedex 05, France
J acqueline Vaissermann
Laboratoire de Chimie Inorganique et Mate´riaux, UMR CNRS 7071, Universite´ Pierre et
Marie Curie, 4 place J ussieu, BP 42, 75252 Paris Cedex 05, France
Received April 8, 2002
Summary: Unprecedented (η5-cyclohexadienyl)Mn(CO)3
complexes bearing an electron-donating group at the end
of the π system have been selectively prepared using Pd
catalysis and primary, secondary cyclic, and acyclic
amines. This catalytic methodology has been extended
to O-, S-, and P-based derivatives. The X-ray structure
of one coupling product exhibits an unusual conforma-
tion in its η5 system.
philes and hydrides.4,5 Nucleophilic attack on the sub-
stituted arene takes place at the 6- or 5-position of the
aromatic ring, depending on the electronic effect of a
substituent.6 Electron-withdrawing substituents such as
chloride in complex 1 are known to induce mainly an
ortho addition, giving complex 2 (Scheme 1, path a).6b,7
In contrast, electron-donating groups (4; Y ) OMe, NR2)
exclusively direct meta addition, yielding complex 5
(Scheme 1, path b).3d Indeed, electronic effects preclude
ortho nucleophilic addition and thereby avoid the for-
mation of the 1-substituted η5-complex 6 (Scheme 1,
path c). In other words, no synthesis of (η5-cyclohexa-
dienyl)manganese complexes substituted with an elec-
tron-donating group at the end of the π-system, 6, had
been previously reported. We thought that a possible
strategy to prepare these complexes might be found in
the reaction of the palladium intermediate 3, arising
from the insertion of Pd(0) into the carbon-chloride
bond of (η5-chlorocyclohexadienyl)manganese complexes
2,8 with nucleophiles such as amine, alcoholate, and
thiolate in a Buchwald-Hartwig type methodology to
afford complex 6 (Scheme 1, path a).9 Therefore, in this
communication we describe an efficient synthesis of
previously unknown complexes using a palladium-
catalyzed coupling reaction. While elaborate catalytic
systems seem to be required and beneficial in Buch-
wald-Hartwig reactions, the present strategy takes
In the course of reactions involving electrophilic η6-
arene metal complexes and nucleophiles,1 η5-cyclohexa-
dienyl transition-metal complexes can be isolated or
transformed in situ into highly fuctionalized arenes or
cyclohexadienes. Those entities coordinated to chro-
mium have been intensively studied, demonstrating
their use in organic synthesis.2
In contrast, relatively few investigations have been
undertaken to exploit the potential of (η5-cyclohexadi-
enyl)manganese complexes as valuable tools for organic
synthesis.3 This is probably due to the fact that, until
recently, the only way to obtain the required (η5-
cyclohexadienyl)manganese complexes consisted of a
nucleophilic addition to the parent η6 complex. Such
reactions are known to be efficient with carbon nucleo-
* To whom correspondence should be addressed. E-mail: rose@
ccr.jussieu.fr (E.R.); rosemun@ccr.jussieu.fr (F.R.).
† Present address: Laboratoire SIRCOB, UPRESA A 8086, Univer-
site´ de Versailles, 45 avenue des Etats-Unis, 78035 Versailles Cedex,
France.
(1) (a) McQuillin, F.; Parker, D. G.; Stephenson, G. R. Transition
Metal Organometallics for Organic Synthesis; Cambridge University
Press: Cambridge, U.K., 1991; p 429. (b) Semmelhack, M. F. In
Comphrensive Organometallic Chemistry; Abel, W., Stone, F. G. A.,
Wilkinson, G., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 12, Chapter
9, p 979. (c) Rose-Munch, F.; Gagliardini, V.; Renard, C.; Rose, E.
Coord. Chem. Rev. 1998, 249, 198. (d) Pike, R. D.; Sweigart, D. A.
Coord. Chem. Rev. 1999, 187, 183. (e) Astruc, D. Chimie organome´t-
allique; EDP Sciences: Les Ulis, France, 2000; p 111. (f) Rose-Munch,
F.; Rose, E. Eur. J . Inorg. Chem. 2002, 1269.
(2) See for example: (a) Semmelhack, M. F.; Hall, H. T., J r.; Farina,
R.; Yoshifuji, M.; Clark, G.; Bargar, T.; Hirotsu, K.; Clardy, J . J . Am.
Chem. Soc. 1980, 101, 3535. (b) Pape, A. R.; Krishna, K. P.; Ku¨ndig,
E. P. Chem. Rev. 2000, 100, 2917. (c) Bernardinelli, G.; Gillet, S.;
Ku¨ndig, E. P.; Ronggang, L.; Ripa, A.; Saudan, L. Synthesis 2001, 13,
2040.
(3) (a) Miles, W. H.; Brinkman, H. R. Tetrahedron Lett. 1992, 33,
589. (b) Lee, T. Y.; Kang, Y. K.; Chung, Y. K.; Pike, R. D.; Sweigart, D.
A. Inorg. Chem. Acta 1993, 214, 125. (c) Roell, B. C.; McDaniel, K. F.;
Vaughan, W. S.; Macy, T. S. Organometallics 1993, 12, 224. (d)
Pearson, A. J .; Gontcharov, A. V.; Zhu, P. Y. Tetrahedron 1997, 53,
3849 and references herein. (e) Pearson, A. J .; Vickerman, R. J .
Tetrahedron Lett. 1998, 39, 5931.
(4) McDaniel, K. F. In Comprehensive Organometallic Chemistry;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford,
U.K., 1995; Vol. 6, Chapter 4, p 93.
(5) Addition of heteronucleophiles usually led to equilibria, revers-
ible reactions, or reactions at the metal center; see, for example: (a)
Evans, E. J .; Kane-Maguire, L. A. P.; Sweigart, D. A. J . Organomet.
Chem. 1981, 215, C27. (b) Chung, Y. K.; Honig, E. D.; Sweigart, D. A.
J . Organomet. Chem. 1983, 256, 277. (c) Schindehutte, M.; Rooyen, P.
H. V.; Lotz, S. Organometallics 1990, 9, 293.
(6) (a) Pauson, P. L.; Segal, J . A. J . Chem. Soc., Dalton Trans. 1975,
1677. (b) Pauson, P. L.; Segal, J . A. J . Chem. Soc., Dalton Trans. 1975,
1683. (c) Stephenson, G. R.; Owen, D. A. Tetrahedron Lett. 1991, 32,
1291. (d) Rose-Munch, F.; Rose, E. Curr. Org. Chem. 1999, 3, 445.
(7) Chung, Y. K.; Williard, P. G.; Sweigart, D. A. Organometallics
1982, 1, 1053.
(8) (a) Prim, D.; Auffrant, A.; Rose-Munch, F.; Rose, E.; Vaisser-
mann, J . Organometallics 2001, 20, 1901. (b) Auffrant, A.; Prim, D.;
Rose-Munch, F.; Rose, E.; Vaissermann, J . Organometallics 2001, 20,
3214.
(9) See for example (a) Hartwig, J . F. Angew. Chem., Int. Ed. Engl.
1998, 37, 2046. (b) Buchwald, S. L. J . Organomet. Chem. 1999, 576,
125. (c) Prim, D.; Campagne, J . M.; J oseph, D.; Andrioletti, B.
Tetrahedron 2002, 58, 2041.
10.1021/om0202773 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 07/19/2002

Communications
Organometallics, Vol. 21, No. 17, 2002 3501
Ta ble 2. P d -Ca ta lyzed Rea ction of
(η5-1-ch lor ocycloh exa d ien yl)Mn (CO)3 Com p lexes
w ith Alcoh ol, Th iols, P h osp h in e, a n d P h osp h ite
Oxid e
Sch em e 1
entry
complex
YH
complex
yield (%)
1a,b
2a,b
3a,b
4a,b
5a,c
6a,c
8
8
8
7
9
10
isoamyl-OH
p-tolyl-SH
C5H11SH
p-tolyl-SH
(EtO)2P(O)H
PPh2H
15
16
17
18
19
20
37
93
73
81
77
65
a
b
Catalyst: Pd2dba3,AsPh3. Base: NaH. c Base: Et3N.
Sch em e 3
Sch em e 2
conditions to afford the corresponding ether, 15, in 37%
yield (entry 1). Alkyl and aryl thioethers 16-18 were
isolated in better yields (73-93%) using the same
methodology (entries 2-4). Extension of this methodol-
ogy to P-based nucleophiles was also successful. Indeed,
diethyl phosphite oxide and diphenylphosphine gave the
corresponding complexes 19 and 20 in 77 and 65%
yields, respectively (entries 5 and 6). Reactions involving
P-based nucleophiles require the use of triethylamine
instead of NaH as a base.
Taking advantage of these observations, we have
carried out further investigations using complex 21, in
which the sp3 carbon is substituted by a phenyl group.12
Combinations of morpholine/Cs2CO3 and p-tolylSH/NaH
under palladium catalysis were effective for the intro-
duction of a nucleophile at position 1 (Scheme 3). No
problem with steric hindrance was detected. Complexes
Ta ble 1. P d -Ca ta lyzed Am in a tion of
(η5-1-ch lor ocycloh exa d ien yl)Mn (CO)3 Com p lexes
entry
complex
YH
complex yield (%)
1a,c
2b,c
3a,c
4a,c
5a,c
7, R1 ) H
HN(CH2CH2)2O
HN(CH2CH2)2O
HNEt2
11
84
0
84
42
0
7, R1 ) H
8, R1 ) 4-OMe
9, R1 ) 4-Me
10, R1 ) 2-OMe HN(CH2CH2)2O
12
13
14
H2NPh-4-OMe
a
b
Catalyst: Pd2dba3, AsPh3. Without catalyst. c Base: Cs2CO3.
10
advantage of the use of a simple Pd/AsPh3 catalytic
combination.
The requisite (η5-1-chlorocyclohexadienyl)Mn(CO)3
complexes 7-10 were readily prepared by hydride
addition to the parent (η6-chloroarene)Mn(CO)3 com-
+
plexes, as already described.11 In a preliminary experi-
ment, morpholine and Cs2CO3 were added to premixed
complex 7, Pd2(dba)3, and AsPh3 in freshly distilled and
degassed THF under a nitrogen atmosphere (Scheme
2). Complete disappearance of the starting material was
observed over 6 h at 60 °C, giving rise to the formation
of 11 in 84% yield (Table 1, entry 1). A control experi-
ment conducted under the same reaction conditions but
without using a catalyst gave no reaction (entry 2).
These initial results prompted us to extend this strategy
to different substituted starting materials and a variety
of amines. Indeed, the (η5-1-chloro-4-substituted cyclo-
hexadienyl)Mn(CO)3 complexes 8 and 9 underwent
amination using secondary and primary amines, re-
spectively (entries 3 and 4). Only complex 10 did not
display the expected amination product, probably due
to steric hindrance (entry 5).
(12) Complex 21 was prepared according to the procedure described
in ref 7.
(13) A typical procedure for the Pd-catalyzed reaction is given by
the preparation of complex 16: Pd2(dba)3 (0.029 g, 0.03 mmol) and
AsPh3 (0.34 g, 0, 11 mmol) were added to a solution of complex 2 (0.089
g. 0.32 mmol) in anhydrous degassed THF (10 mL). After 15 min at
room temperature, a THF solution of p-methylthiophenol (0.040 g, 0.32
mmol) and NaH (0.005 g, 0.38 mmol) was introduced. The reaction
mixture was refluxed overnight, poured into cold water (100 mL), and
extracted with 50 mL of pentane; the organic phase was washed with
water (2 × 20 mL), dried over magnesium sulfate, and filtered. Solvents
were evaporated under a nitrogen flush. The residue obtained was
purified by silica gel chromatography (pentane) to deliver complex 16
as a yellow solid in 93% yield. IR (CH2Cl2): ν(CO) 1917, 1998 cm-1
.
1H NMR (CDCl3; 200 MHz): δ 2.91 (dd, J ) 13 and 6.5 Hz, 1H, H-6
endo), 2.48 (d, J ) 13 Hz, 1H, H-6 exo), 2.32 (s, 3H), 3.01 (d, J ) 6.5
Hz, 1H, H-5), 3.45 (s, 3H), 4.96 (d, J ) 5.5 Hz, 1H, H-2), 5.65 (d, J )
5.5 Hz, 1H, H-3), 7.10 (d, J ) 8 Hz), 7.21 (d, J ) 8 Hz). 13C NMR
(CDCl3; 100 MHz): δ 21.2 (CH3), 33.0 (C-6), 36.3 (C-5), 54.5, (OMe),
65.0 (C-1), 66.9 (C-3), 96.2 (C-2), 128.8, 130.0, 131.7, 133.8, (C6H4),
142.7 (C-4), 221.3 (CO). Anal. Calcd: C, 55.14; H, 4.08. Found: C,
55.12; H, 4.10. Crystal data for 16: C17H15MnO4S, Mr ) 370.3,
orthorhombic, space group P212121, a ) 8.463(2) Å, b ) 13.716(6) Å, c
) 14.385(3) Å, Dc ) 1.47 g cm-3, Z ) 4, crystal size 0.10 × 0.40 × 0.40
mm, µ ) 8.94 cm-1, 2325 data collected at 295 K (θ range 1-28°) on
an Enraf-Nonius CAD-4 diffractometer. An absorption correction using
DIFABS (Tmin ) 0.65, Tmax ) 1) was applied. Anomalous dispersion
terms and correction of secondary extinction were applied. The
structure was solved by direct methods (SHELXS) and refined on F
(CRYSTALS) by least-squares analysis using anisotropic thermal
parameters for all non-hydrogen atoms. H atoms were introduced in
calculated positions and were allocated an overall isotropic thermal
parameter. A total of 1356 reflections with I > 3σ(I) were used to solve
and refine the structure to R ) 0.0445 and Rw ) 0.0516, 210 least-
squares parameters, GOF ) 1.02.
Next we examined the palladium-catalyzed reactions
of various heteronucleophiles such as O-, S-, and P-
based derivatives (Table 2). Preformed sodium isoamy-
late reacted with complex 8 under the aforementioned
(10) (a) Farina, V.; Krishnan, B.; Marshall, D. R.; Roth, G. P. J . Org.
Chem. 1993, 58, 5434. (b) For an application with tricarbonylchromium
complexes see: Prim, D.; Tranchier, J . P.; Rose-Munch, F.; Rose, E.;
Vaissermann, J . Eur. J . Inorg. Chem. 2000, 5, 901.
(11) Balssa, F.; Gagliardini, V.; Rose-Munch, F., Rose, E. Organo-
metallics 1996, 15, 4373.

3502 Organometallics, Vol. 21, No. 17, 2002
Communications
22 and 23 were isolated in 55 and 91% yields, respec-
tively.
Well-formed crystals suitable for X-ray analysis were
obtained after crystallization of complex 16 from a
hexane/diethyl ether mixture.13 The structure undoubt-
edly confirmed the regioselectivity of the reaction.
Interestingly, the η5-cyclohexadienyl moiety did not
exhibit the expected classical five-coplanar-carbon ge-
ometry (C1, C2, C3, C4, C5)14 with one carbon, C6, lying
out of this plane. Rather, we observed that two carbons,
C6 and C2, are located out of the plane formed by the
other C1, C3, C4, and C5 sp2 carbons and away from the
metal center. Indeed, the Mn-C1/C3/C4/C5 bond lengths
lie between 2.15 and 2.20 Å, whereas Mn-C2 and Mn-
C6 bonds manifest lengths of 2.38 and 2.48 Å, respec-
tively. The dihedral angles between the C1,C3,C4,C5/
C1,C2,C3 and C1,C3,C4,C5/C1,C5,C6 planes reach 19.8 and
25.2°, respectively.
This could be better described as a π-allyl C3, C4, C5
σ-alkyl C1 derivative15 which might be represented by
a “high-heeled-shoe” conformation, as shown in Figure
1. For the moment it is difficult to explain this unex-
pected structure, and we can only suggest that the
thiophenyl residue might play an important role in
forcing the complex to adopt this conformation in the
solid state.
In conclusion, we have successfully developed a
general palladium-catalyzed approach to new (η5-cyclo-
hexadienyl)Mn(CO)3 complexes bearing electron-donat-
ing groups at the terminus of the π-system. These
complexes cannot be synthesized using classical meth-
ods. An X-ray structure of one of the C1-substituted
cyclohexadienyl manganese compounds shows an un-
F igu r e 1. X-ray structure of complex 16 with the number-
ing scheme and the “high heeled-shoe” analogy. Thermal
ellipsoids are presented at the 30% probability level.
Selected bond lengths (Å) and angles (deg): Mn-C1 ) 2.17,
Mn-C2 ) 2.38, Mn-C3 ) 2.15, Mn-C4 ) 2.20, Mn-C5 )
2.17, Mn-C6 ) 2.46; [C1C2C3]/[C1C3C4C5] ) 19.8, [C1C5C6]/
[C1C3C4C5] ) 25.5.
usual conformation which contravenes the “rule” of
planarity among the five sp2 carbons. Further investiga-
tions on the structural and chemical properties of such
compounds are currently in progress.
Ack n ow led gm en t. We thank the CNRS, EU Train-
ing and Mobility of Researchers Program (Contract No.
ERBFMRXCT-CT98-0166), and the EU COST D14
Program for financial support and the Ministe`re de
l’Education Nationale et de la Recherche for a MENRT
grant to A.A.
(14) For X-ray studies of (η5-cyclohexadienyl)Mn(CO)3 complexes,
see for example: (a) Lee, T. Y.; Bae, H. K.; Chung, Y. K.; Hallowse,
W. A.; Sweigart, D. A. Inorg. Chim. Acta 1994, 224, 147. (b) Dullaghan,
C. A.; Carpenter, G. B.; Sweigart, D. A. Chem. Eur. J . 1997, 3, 75. (c)
Balssa, F.; Gagliardini, V.; Lecorre-Susanne, C.; Rose-Munch, F.; Rose,
E.; Vaissermann, J . Bull. Chem. Soc. Fr. 1997, 134, 537. (d) Renard,
C.; Valentic, R.; Rose-Munch, F.; Rose, E. Organometallics 1998, 17,
1587. (e) Rose, E.; Lecorre-Susanne, C.; Rose-Munch, F.; Renard, C.;
Gagliardini, V.; Tedji, F.; Vaissermann, J . Eur. J . Inorg. Chem. 1999,
3, 421. (f) Son, S. U.; Paik, S. J .; Park, K. H.; Lee, Y. A.; Lee I. S.;
Chung, Y. K., Sweigart, D. A. Organometallics 2002, 21, 239.
(15) One of the reviewers mentioned an interesting example of a
σ,π-cyclohexenyl complex of Mn (Pike, R. D.; Ryan, W. J .; Lennhoff,
N. S.; Van Epp, J .; Sweigart, D. A. J . Am. Chem. Soc. 1990, 112, 4798)
presenting a striking resemblance to that described here. However,
in this structure, C2 atom is an sp3 carbon not bonded to the Mn atom.
Su p p or tin g In for m a tion Ava ila ble: Text giving spectral
data for the new compounds and tables of crystal data, atomic
coordinates, and bond distances and angles for complex 16.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM0202773