Palladium-catalyzed chloride substitution of η5-(Chlorocyclohexadienyl)Mn(CO)3 complexes: An access to novel η6-(Arene)Mn(CO)3+ cations

1898

Organometallics 2003, 22, 1898-1913

P a lla d iu m -Ca ta lyzed Ch lor id e Su bstitu tion of

η⁵-(Ch lor ocycloh exa d ien yl)Mn (CO)₃Com p lexes: An

+

Access to Novel η⁶-(Ar en e)Mn (CO)₃Ca tion s

Audrey Auffrant, Damien Prim,^†Franc¸oise Rose-Munch,* Eric Rose, and

Ste´phanie Schouteeten

Laboratoire de Synthe`se Organique et Organome´tallique, UMR CNRS 7611, Universite´ Pierre

et Marie Curie, Tour 44 1er e´tage, BP 181, 4 Place J ussieu, 75252 Paris Cedex 05, France

J acqueline Vaissermann

Laboratoire de Chimie Inorganique et Mate´riaux Mole´culaires, Unite´ de Recherche

7071-CNRS, Universite´ Pierre et Marie Curie, 4 Place J ussieu, BP 42,

75252 Paris Cedex 05, France

Received December 17, 2002

Functionalization of η⁵-(chlorocyclohexadienyl)Mn(CO)₃complexes was achieved by pal-

ladium-catalyzed reactions using Pd₂(dba)₃in the presence of AsPh₃. Arylation, carbonylation,

and substitution by alkyne-, alkene-, and heteroatom-based nucleophiles were performed,

giving rise to functionalized η⁵complexes whose structures have been investigated by NMR

and X-ray studies. These η⁵complexes are valuable precursors upon exo-hydride abstraction,

of the corresponding η⁶cations, substituted by resonance-withdrawing groups, whose

conformations in solution and in the solid state have been studied.

In tr od u ction

of the metal is mentioned in a mere handful of papers.

Ipso chloride substitution in η⁶-(chloroarene)tricarbon-

ylmanganese complexes allows a clean nucleophile

introduction,⁴but it has been demonstrated that such

a strategy was restricted to amino, oxo, and thio

nucleophiles (eq 1, path a).

Arene activation by a tricarbonylmetal fragment

greatly modifies the reactivity of the arene ring by

imparting high electrophilicity.¹Among all transition

metals commonly used, manganese appears very at-

tractive because of the high electrophilic feature of its

corresponding cationic complexes. Nucleophilic attacks

on the arene ligand, metal center, or carbonyl ligands

have been widely studied.²This specific reactivity has

been exploited for synthetic purposes and applied to the

preparation of natural products.³Nevertheless, until

now these complexes remained relatively undeveloped

compared to their chromium^1eand iron counterparts.^1f

Indeed, chemistry at the carbon π-system without loss

The main reactions that are described for Mn com-

plexes are addition reactions leading to neutral and

stable η⁵-(cyclohexadienyl)tricarbonylmanganese com-

plexes (eq 1, path b). Only a few studies^5adealing with

the reactivity of these neutral complexes have been

undertaken and involve attack at the terminus of the

^†Present address: Laboratoire SIRCOB, Univ. Versailles-Saint

Quentin, 45 Avenue des Etats-Unis, 78035 Versailles, France.

(1) (a) McQuillin, F.; Parker, D. G.; Stephenson, G. R. Transition

Metal Organometallics for Organic Synthesis; Cambridge University

Press: Cambridge, U.K., 1991. (b) Semmelhack, M. F. In Comprehensive

Organometallic Chemistry; Abel, W., Stone, F. G. A., Wilkinson, G.,

Eds.; Pergamon: Oxford, U.K., 1995; Vol. 12, Chapter 9, p 979. (c) Pike,

R. D.; Sweigart, D. A. Coord. Chem. Rev. 1999, 187, 183. (d) Astruc,

D. Chimie Organome´tallique; EDP Sciences: Les Ulis, France, 2000.

(e) Rose-Munch, F.; Rose, E. In Modern Arene Chemistry; Astruc, D.,

Ed.; Wiley-VCH: 2002; Chapter 11, p 368. (f) Astruc, D.; Nlate, S.; Ruiz,

J . In Modern Arene Chemistry; Astruc, D., Ed.; Wiley-VCH: New York,

2002; Chapter 12, p 400.

(2) See for example: (a) Bernhardt, R. J .; Eyman, D. P. Organome-

tallics 1984, 3, 1445. (b) Morken, A. M.; Eyman, D. P.; Wolff, M. A.;

Schauer, S. J . Organometallics 1993, 12, 725. (c) Pike, R. D.; Carpenter,

G. B. Organometallics 1993, 12, 1416. (d) Cao, Y.; Woo, K.; Yeung, L.

K.; Carpenter G. B.; Sweigart, D. A. Organometallics 1997, 16, 178.

(e) Seo, H.; Lee, S. G.; Shin, D. M.; Hong, B. K.; Hwang, S.; Chung, D.

S.; Chung, Y. K. Organometallics 2002, 21, 3417. (f) Rose-Munch, F.;

Rose, E. Eur. J . Inorg. Chem. 2002, 1269.

(4) (a) Pauson, P. L.; Segal, J . A. J . Chem. Soc., Dalton Trans. 1975,

1677. (b) Pearson, A. J .; Shin, H. J . Org. Chem. 1994, 59, 2314, and

references therein.

(5) (a) McDaniel, K. In Comprehensive Organometallic Chemistry;

Abel, W., Stone, F. G. A., Wilkinson, G.; Eds.; Pergamon: Oxford, U.K.,

1995; Vol. 6, Chapter 4, p 93. (b) Sheridan, J . B.; Padda, R. S.; Chaffee,

K.; Wang, C.; Huang, Y.; Lalancette, R. J . Chem. Soc., Dalton Trans.

1 1992, 1539. (c) Roell, B. C.; McDaniel, K. F.; Vaughan, W. S.; Macy,

T. S. Organometallics 1993, 12, 224. (d) Kane-Maguire, L. A. P.; Honig,

E. D.; Sweigart, D. A. Chem. Rev. 1984, 84, 525. (e) Hyeon, T. H.;

Chung, T. M.; Chung, Y. K. Bull. Korean Chem. Soc. 1989, 10, 500. (f)

Pike, R. D.; Ryan, W. J .; Lenhoff, N. S.; Van Epp, J .; Sweigart, D. A.

J . Am. Chem. Soc. 1990, 112, 4798. (g) Pearson, A.; Vickerman, R. J .

Tetrahedron Lett. 1998, 39, 5931. (h) Woo, K.; Cao, Y.; Li, H.; Yu, K.;

Carpenter, G. B.; Sweigart, D. A.; Robinson, B. H. J . Organomet. Chem.

2001, 84, 630.

(3) (a) Miles, W. H.; Brinkman, H. R. Tetrahedron Lett. 1992, 33,

589. (b) Pape, A. R.; Kaliappan, K. P.; Ku¨ndig, E. P. Chem. Rev. 2000,

100, 2917, and references therein.

Publication on Web 03/29/2003

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1899

π-system leading to the formation of cyclohexadienes,

either via transient anionic η⁴-cyclohexadiene Mn

complexes,^5c,6via neutral η⁴-dicarbonylnitrosylmanga-

nese complexes,^5d-hor via an acylmetalate anionic η⁵

complex.^5bThe corresponding substituted cyclohexa-

dienes were formed after an oxidative process (eq 2, path

a). Several years ago, in the course of the reactivity

study of manganese complexes, we described the first

cine and tele nucleophilic substitutions of η⁵-(X-substi-

tuted-cyclohexadienyl)MnCO₃complexes after treat-

ment with hydrides and a proton source (eq 2, path b).⁷

However, the electrophilic character of the cyclohexa-

dienyl ligand is restricted to hydride and stabilized

nucleophiles. Another special feature of η⁵-(cyclohexa-

dienyl)Mn(CO)₃complexes is their rearomatization,

which can only proceed through exo-hydride abstraction.

In this regard, rearomatization of such complexes

obtained through nucleophilic addition into the parent

η⁶pattern remains unsuccessful without loss of the

metal (eq 2, path c).

a general concept for the functionalization of η⁵-Mn(CO)₃

complexes based on palladium catalysis (eq 4). We

planned to use such reactions in a three-step methodol-

+

ogy to synthesize new cationic η⁶-(arene)Mn(CO)₃

-

complexes starting from η⁶-(chloroarene)Mn(CO)₃⁺. The

complete sequence started with hydride addition, lead-

ing to neutral η⁵complexes (eq 4, path a). The second

step involved a palladium-catalyzed functionalization

of the newly formed η⁵derivatives (eq 4, path b).

+

Delivery of the desired η⁶-(arene)Mn(CO)₃complexes

was finally attempted by hydride abstraction (eq 4, path

c). In this paper we describe the details of this study

along with the structures of novel η⁵and η⁶Mn

complexes.

Resu lts a n d Discu ssion

F u n ction a liza tion of η⁵-(Ch lor ocycloh exa d ien yl)

Mn (CO)₃Com p lexes. η⁵-(Chlorocyclohexadienyl)Mn-

(CO)₃complexes, used as starting material in this work,

were readily prepared by nucleophilic addition of

hydride^4a,6a,10or phenylmagnesium bromide¹¹to various

substituted η⁶-(chloroarene)Mn(CO)₃⁺(eq 5). As already

described,¹⁰hydride addition to chlorobenzene and 4-

and 2-chlorotoluene tricarbonylmanganese complexes

1a , 1b, and 1d , respectively, lead to mixtures of two

regioisomers. The 2:3 ratio strongly depends on elec-

tronic effects of the substituents. In contrast, due to the

donor ability of the methoxy group in complexes 1c and

1e, addition is exclusively directed ortho to the chlorine

atom, selectively generating complexes 2c and 2e.

Whereas the presence of the highly withdrawing Mn⁺-

(CO)₃entity renders the carbon-chlorine bond of η⁶-

(chloroarene) or η⁵-(cyclohexadienyl)Mn(CO)₃complexes

reactive toward Pd(0) oxidative addition, to our knowl-

edge, no report of palladium-catalyzed functionalization

of such complexes has been reported. In contrast to

chromium analogues,⁹although the palladium entity

inserts into the carbon-chlorine bond of η⁶-(chloroarene)-

Mn⁺(CO)₃complexes, the resulting stable bimetallic

Mn-Pd complex did not afford any classical coupling

product⁸(eq 3).

Taking into account the specificity of arene manga-

nese complex chemistry and with the aim of solving the

long-standing reactivity problems of such complexes

toward Pd-catalyzed reactions, we wish hereby to report

(6) (a) Brookhart, M.; Lamanna, W.; Pinhas, A. R. Organometallics

1983, 2, 683. (b) Brookhart, M.; Lukacs, A. J . Am. Chem. Soc. 1984,

106, 4161. (c) Rush, P. J .; Noh, S. K.; Brookhart, M. Organometallics

1986, 5, 1745

(7) Balssa, F.; Gagliardini, V.; Rose-Munch, F.; Rose, E. Organo-

metallics 1996, 15, 4373.

(8) Carpentier, J . F.; Castanet, Y.; Brocard, J .; Mortreux, A.; Rose-

Munch, F.; Susanne, C.; Rose, E. J . Organomet. Chem. 1995, 493, C25.

(9) (a) Carpentier, J . F.; Petit, F.; Mortreux, A.; Dufaud, V.; Basset,

J . M.; Thivolle-Cazat, J . J . Mol. Catal. 1993, 81, 1. (b) Prim, D.;

Tranchier, J . P.; Rose-Munch, F.; Rose, E.; Vaissermann, J . Eur. J .

Inorg. Chem, 2000, 901. (c) Prim, D.; Auffrant, A.; Rose-Munch, F.;

Rose E.; Vaissermann, J . Organometallics 2001, 20, 1901.

Ch oice of th e Ca ta lytic System . Our study began

with the determination of the best catalytic system for

the carbon-carbon bond formation. The efficiency of

various catalytic systems was compared for the coupling

(10) Pauson, P. L.; Segal, J . A. J . Chem. Soc., Dalton Trans. 1 1975,

1683.

(11) Chung, Y. K.; Williard, P. G.; Sweigart, D. A. Organometallics

1982, 1, 1053.

1900 Organometallics, Vol. 22, No. 9, 2003

Auffrant et al.

Ta ble 1. Va r ia tion of th e Na tu r e of L for Stille

Rea ction

Ta ble 2. Stille Rea ction w ith

η⁵-(1-Ch lor ocycloh exa d ien yl)Mn (CO)₃Com p lex

reaction

time (h)

4a

(yield %)

reaction

time (h)

complex

(yield %)

entry

L

entry

R¹

complex

Ar

1

2

3

4

5

6

PPh₃

dppf

P(OEt)₃

P(^tBu)₃

AsPh₃

SbPh₃

17.5

2

6

24

20

4.5

1

2

3

4

5

H

2a

2b

2c

2d

Th

Ph

Th

18

24

20

5a (51)

4b (45)

5b (48)

5c (78)

5d (53)

4-Me

4-OMe

2-Me

52

60^a

a

Ta ble 3. Stille Rea ction w ith

η⁵-(2-Ch lor ocycloh exa d ien yl)Mn (CO)₃Com p lexes

Formation of 20% of 4′a was additionally observed.

reaction between complex 2a and tributylphenyltin in

DMF at room temperature. Pd₂dba₃was used as pre-

catalyst in combination with different ligands labeled

L (Table 1). A Stille type reaction was chosen as a test

reaction due to its well-documented mechanism and

wide usage. Moreover mild reaction conditions for this

process with areneCr(CO)₃were developed in our

laboratory.^9b

complex 6

(yield %)

complex 3

R¹

3a

3b

3d

H

5-Me

1-Me

6a (58)

6b (30)

6d (43)

The results obtained with complex 2a are gathered

in Table 1. To our surprise, only decomplexation of the

starting material was observed using the classical

triphenylphosphine ligand (Table 1, entry 1). The use

of an electron-rich bidentate phosphine, dppf, a bulky

phosphine, P(^tBu)₃, and a phosphite ligand, P(OEt)₃, was

also unsuccessful (entries 2-4). We next turned our

attention to an arsine ligand, AsPh₃, and were able to

obtain the desired coupling product in 52% yield (entry

5).^9cBetter results with AsPh₃are in agreement with

the observations of Farina and co-workers.¹²The ac-

celeration of the transmetalation step in the presence

of AsPh₃was correlated to its higher decoordination

ability. Nevertheless, the strict selectivity observed

cannot be explained. However, we can put forward the

hypothesis of an interaction between Mn-, Pd-, and

P-based ligands which could be responsible for the

hindered formation of the catalytic system, its degrada-

tion, and, consequently, its lack of efficiency. As support

for our explanation, it has been observed that η⁶

complexes were stable in the presence of phosphines,⁸

whereas complexes of lower hapticity could be decoor-

dinated under such conditions.⁵To increase the yield

of the coupling product, we tried triphenylantimony,

SbPh₃. In this case two coupling products were isolated:

complexes 4a and 4′a in 60 and 20% yield, respectively

(Table 1, entry 6). In contrast to Farina’s results^12awe

obtained high yields of the expected coupling products

in a shorter reaction time; however the reaction was less

chemoselective. Decomplexation of the starting mate-

rial, probably favored by the steric hindrance due to the

Sb ligand, provided carbon monoxide, involved in the

formation of complex 4′. Formation of carbonylation

products under non-carbonylative conditions has al-

ready been reported in the case of tricarbonylchromium

complexes.^9b,13The reaction conducted without a cata-

lytic system did not give any new product; there was

no direct substitution of the chlorine atom. To avoid the

problem of separation of two coupling products, we used

for the palladium-catalyzed reactions presented in this

paper the association of Pd₂(dba)₃and AsPh₃(noted [Pd]

in the equations and in the tables), which appeared

more efficient and selective.

Stille Rea ction . Having in hand a suitable catalytic

system, we first examined Stille arylation of several η⁵-

(1-chloro-R¹-cyclohexadienyl)Mn(CO)₃(2, R¹) 4-Me,

4-OMe, 2-Me) (Table 2).

Thienyltributyltin reacted in the same way as phenyl-

tributyltin (Table 1, entry 5) with complex 2a to deliver

complex 5a in 51% yield (Table 2, entry 1) as well as

with complex 2b to deliver complexes 4b and 5b in 45

and 48% yields, respectively (Table 2, entries 2 and 3).

The reaction path is weakly sensitive to the nature and

to the position of the R¹substituent in the π-system

(Table 2, entries 3-5). Indeed ortho-substituted complex

2d led to complex 5d in 53% yield (entry 5). Further-

more, the electron-withdrawing ability of the Mn(CO)₃

entity allowed the oxidative addition of Pd⁽⁰⁾even in the

presence of an electron-donating substituent (Table 2,

entry 4).

Arylation of η⁵-(2-chlorocyclohexadienyl)Mn(CO)₃re-

gioisomer 3 with 2-tributylstannylthiophene (noted Th-

SnBu₃) was also performed under the same reaction

conditions (reaction time: 24 h) (Table 3).

Complex 3a gave the corresponding coupling adduct

in a slightly better yield (58%) than the methyl-

substituted complexes 3b and 3d (30 and 43%, respec-

tively). In these cases, again no strong steric hindrance

and substituent effects on the reaction path were

observed. However, the yields reported in Table 3 are

generally lower than those in Table 2 and reaction times

longer (24 h in Table 3). These observations led us to

(12) (a) Farina, V.; Krishnan, B. J . Am. Chem. Soc. 1991, 113, 9585.

(b) Farina, V.; Krishnan, B.; Marshall, D. R.; Roth, G. P. J . Org. Chem.

1993, 58, 5434.

(13) Kamikawa, K.; Watanabe, T.; Uemura, M. J . Org. Chem. 1996,

61, 1375.

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1901

Ta ble 4. Syn th esis of Alk yn e-Su bstitu ted

η⁵-(Cycloh exa d ien yl)Mn (CO)₃Com p lexes

F igu r e 1. Evolution of percentages of 2a (2) and 5a (9).

R¹

reaction

time (h)

yield

(complex)

R³

postulate that the kinetics of the arylation process could

be very different for the 1- and 2-chlorocyclohexadienyl

regioisomers. If this hypothesis was confirmed, it would

be possible to realize a selective functionalization of one

regioisomer starting from a mixture of regioisomers that

would avoid purification of the starting η⁵complex. For

this purpose, we thought that such an experiment could

be monitored by ¹H NMR, where integration of H³

protons could allow the determination of 2a :3a and 5a :

4-OMe (2c)

H (2a )

H

1

0.5

79 (9)

77 (9)

91 (8)

ZnCl

SnBu₃

or a triple C-C bond. We were first interested in the

synthesis of alkyne-substituted η⁵-cyclohexadienyl com-

plexes, precursors of the corresponding alkyne-substi-

tuted η⁶-arene complexes that are difficult to obtain by

direct complexation.¹⁴But in a first step, we wanted to

verify if direct substitution of the chlorine atom was

possible. When reaction was attempted with complex

2a in the presence of lithium phenylacetylide, no

substitution product was isolated and the starting

material remained unchanged. Thus, we alternatively

tried a Pd-catalyzed reaction. To compare the efficiency

of various alkyne coupling methodologies, we performed

Sonogashira, Negishi, and Stille reactions to introduce

a phenylacetylene moiety to η⁵-(chlorocyclohexadienyl)-

Mn(CO)₃complex (Table 4). Complex 9 was obtained

in 79% yield after 1 h using directly phenylacetylene.

Following the Negishi strategy, complex 2c reacted with

in situ generated ethynylbenzene zinc chloride, in the

presence of Pd₂dba₃and AsPh₃at room temperature in

THF to afford after 1 h complex 9 in 77% yield. Finally

we investigated the Stille coupling reaction between

tributylstannylethynylbenzene and complex 2a with the

same catalytic system in DMF at room temperature.

The corresponding alkyne 8 was obtained in 91% yield

after 0.5 h. This last procedure represented the most

efficient strategy in comparison with the other results

gathered in Table 4.

1

6a ratios (eq 6). Indeed H NMR spectra showed large

differences for the H³resonance of complexes 2a and

3a : δ(H₃)_2a) 5.72 ppm and δ(H₃)_3a) 6.14 ppm.

Corresponding coupling products 5a and 6a exhibit

similar behavior: δ(H₃)_5a) 5.86 ppm and δ(H₃)_6a) 6.35

ppm (eq 6). A mixture of complexes 2a and 3a in 54:46

ratio was reacted with tributylstannylthiophene under

the previously described conditions.

ThSnBu₃and η⁵-(1-chlorocyclohexadienyl)Mn(CO)₃

2a , which we thought to be the most reactive isomer,

were introduced in stoichiometric amount. Evolution of

Nevertheless, the Sonogashira coupling reaction,

which avoided the preparation of stannylated reagents

or Zn derivatives and which used a commercially

available alkyne, was the most useful way to introduce

a triple bond on η⁵manganese complexes, the yield

being 79%. Thus, this reaction was extended to other

alkynes.

1

the reaction mixture was followed by H NMR (Figure

1). After 2 h, only 2a reacted, ratios 2a :3a and 5a :6a

being 16:84 and 100:0, respectively. The same trend was

observed after 3.5 h; that is, the formation of 5a went

on while 3a hardly began to react. After 15 h the

reaction was finished: complex 2a was almost totally

arylated, whereas complex 3a scarcely reacted.

Surprisingly these data clearly show selective aryla-

tion of one regioisomer. Indeed η⁵-(1-chlorocyclohexa-

dienyl)Mn(CO)₃reacted faster than η⁵-(2-chlorocyclo-

hexadienyl)Mn(CO)₃, whereas the arene ring C₁carbon

has more sp³character than the C₂carbon. Thus

electronic effects are in favor of the reverse order of

reactivity. However, another explanation for the experi-

mental observations may be steric, as C₂in contrast to

C₁is eclipsed by a Mn-CO vector. So the higher steric

hindrance of C₂compared to C₁might cause this

impressive difference of reactivity.

We used mild conditions¹⁵in order to preserve the

metallic fragment during the course of the reaction

(Table 5). Complex 2a reacted with trimethylsilyl-

acetylene in the presence of Pd₂dba₃and AsPh₃at

35 °C in NEt₃for 7 h to afford complex 10a in 40%

yield. The same reaction performed with complex 2c

delivered the coupling product 10c in 78% yield.

To study the influence of the chlorine position in the

π-system for the efficiency of introducing the triple bond,

a Stille reaction was performed with another regioiso-

mer: η⁵-(2-chlorocyclohexadienyl)Mn(CO)₃(eq 7). Com-

plex 3b reacted with tributylstannyl ethynylbenzene in

(14) J ackson, J . D.; Villa, S. J .; Bacon, D. S.; Pike, R. D.; Carpenter,

G. B. Organometallics 1994, 13, 3972.

(15) Ravikanth, M.; Stachan, J . P.; Li, F.; Lindsey, J . S. Tetrahedron

1998, 54, 7721.

In tr od u ction of Mu ltip le Bon d s. We next investi-

gated the substitution of the chlorine atom of the

cyclohexadienyltricarbonylmanganese moiety by a double

1902 Organometallics, Vol. 22, No. 9, 2003

Auffrant et al.

Ta ble 5. Son oga sh ir a Cou p lin g Rea ction w ith

Com p lexes 2

we turned our attention to Heck type reactions. We

chose acrylate as a coupling partner. Complex 2c

reacted with phenylacrylate to afford complex 14 in 18%

yield (eq 9). Application of J effery conditions by addition

of a quaternary ammonium salt¹⁷did not allow us to

improve the yield. Using ethyl acrylate, complex 15 was

isolated in a modest 13% yield.

R¹

complex

(yield %)

(complex)

R²

H (2a )

4-OMe (2c)

SiMe₃

10a (40)

10c (78)

DMF at room temperature for 30 min to deliver complex

11 in 95% yield. Thus, for the introduction of a triple

bond, no kinetic difference between regioisomers (1-

chlorocyclohexadienyl)Mn(CO)₃2 and (2-chlorocyclo-

hexadienyl)Mn(CO)₃3 was noticed. No satisfactory

explanation has been found yet.

Ca r bon yla tion Rea ction s. The success of the cou-

pling reactions prompted us to investigate the fate of

these reactions under carbon monoxide atmosphere.

Formation of intermediate A by Pd insertion in the

C-Cl bond was established in the last sections (eq 10).

CO insertion on complex A would give access to the

acylpalladium B, whose trapping by various nucleo-

philes could lead to η⁵-(cyclohexadienyl)Mn(CO)₃com-

plexes substituted by resonance-withdrawing groups,

which were hitherto unknown in the literature (eq 10).

The synthesis of η⁵-(cyclohexadienyl)Mn(CO)₃substi-

tuted by a double bond could be achieved by Stille or

Heck reactions. For the former, we used tributylstyryl-

stannane, prepared by hydrostannylation of phenyl-

acetylene¹⁶as an equimolar mixture of isomers Z and

E. Complex 2c reacted smoothly with tributylstyryl-

stannane in DMF at room temperature in the presence

of Pd₂dba₃and AsPh₃to afford after 24 h the expected

coupling product 12 as a mixture of isomers Z and E,

which could be separated by silica gel flash chromatog-

raphy. Complexes 12Z and 12E were obtained in 31 and

32% yield, respectively (eq 8).

Three types of nucleophiles have been used: stannyl

derivatives for the preparation of ketones, classical

nucleophiles such as alcohol, amine, and thiol for the

synthesis of carboxylic acid derivatives, and alkynes or

alkenes to introduce yne-one or ene-one fragments.

Carbonylation reactions were performed under CO

atmosphere, using the previously described protocol. All

experimental steps were accompanied by significant

coloration changes of the solution from bright yellow to

brown after addition of the catalyst. This color progres-

sively disappeared, turning clear yellow. This change

was attributed to the beginning of the oxidative addi-

tion.¹⁸

The same coupling reaction performed starting from

η⁵-(2-chlorocyclohexadienyl)Mn(CO)₃3a evolved slowly

(3 days) to give complexes 13 in 29% yield as an

inseparable mixture of Z and E isomers (eq 8). Their

1:1 ratio was determined by NMR, confirming the

preservation of the original isomer ratio as already

observed for complex 12. Moreover, as we have already

observed for arylation processes, regioisomer (1-chloro-

cyclohexadienyl)Mn(CO)₃2 is much more reactive than

(2-chlorocyclohexadienyl) Mn(CO)₃3.

We first studied the catalyzed carbonylation of a

series of η⁵-(chlorocyclohexadienyl)Mn(CO)₃2 under CO

atmosphere in the presence of Pd₂dba₃, AsPh₃, and

stannous derivatives as a source of the second nucleo-

phile R²Y (Table 6).

Reaction of η⁵-(1-Cl-4-Me-cyclohexadienyl)Mn(CO)₃

2b and 2-tributylstannylthiophene gave the thienyl

ketone 16b in 90% yield after refluxing the reaction

mixture for 2 h (Table 6, entry 1). In the case of complex

To complete this study of palladium-catalyzed reac-

(17) J effery, T. Tetrahedron 1996, 52, 10113.

tions of η⁵-(chlorocyclohexadienyl)Mn(CO)₃with olefins,

(18) During all these processes reaction mixtures have to be kept

carefully under CO atmosphere in order to avoid the formation of direct

coupling compounds as byproducts. Auffrant, A.; Prim, D.; Rose-Munch,

F.; Rose, E.; Vaissermann, J . Organometallics 2001, 20, 3214.

(16) Zhang, H. X.; Guibe´, F.; Balavoine, G. J . Org. Chem. 1990, 55,

1857.

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1903

Ta ble 6. Syn th esis of Keto-Su bstitu ted

Ta ble 7. Syn th esis of η⁵-(Cycloh exa d ien yl)Mn (CO)₃

η⁵-(Cycloh exa d ien yl)Mn (CO)₃Com p lexes

Su bstitu ted by Ca r boxylic Acid Der iva tives

reaction

time (h)

complex

(yield %)

R¹

R

complex

R²

complex

(yield %)

entry

R²Y

PhOH

MeOH

NH(CH₂CH₂)₂O

p-tolylSH

base

R²

1

2

3

4

5

6

7

8

4-Me

H

Ph

H

Ph

H

2b

2c

2f

2b

2c

2f

Th

Bu

Me

Th

H

2

3

16b (90)

16c (92)

16f (73)

17b (56)

17c (45)

18 (69)

4-OMe

4-Me

4-OMe

2-Me

1

2

3

4

NaH

OPh

OMe

20 (71)

21^a

22 (48)

23 (22)

Et₃N

K₂CO₃

NaH

2

N(CH₂CH₂)₂O

p-tolylS

2.5

24

18

a

Not isolated.

2d

2c

16d (26)

4-OMe

Taking advantage of the easy substitution of the

chlorine atom by alkene, alkyne, and carbonyl function-

alities, we were interested in associating these different

procedures to synthesize yne- or ene-ones. We performed

Sonogashira reactions under CO atmosphere in order

to obtain yne-ones. Complex 24 was isolated in 74%

yield by reacting complex 2c and trimethylsilylacetylene

in the presence of Pd₂dba₃/AsPh₃in NEt₃at 40 °C (eq

12).

2c the ketone 16c was isolated in a similar yield (Table

6, entry 2). The same reaction could be performed with

complex 2f, whose sp³carbon is substituted by a phenyl

group, to give complex 16f in 73% yield (Table 6, entry

3).

This strategy has been extended to other stannous

derivatives for the synthesis of alkyl ketones. Using

SnBu₄as nucleophile starting from complexes 2b and

2c, compounds 17b and 17c were obtained in 56 and

45% yield, respectively (Table 6, entries 4, 5). The same

reaction was performed with complex 2f and Me₄Sn to

afford methyl ketone 18 in 69% yield (Table 6, entry 6).

Thus no steric hindrance occurred in the case of complex

2f. This is undoubtedly due to the distance between the

phenyl substituent on the sp³carbon and the C₁carbon,

where the reaction took place. Reaction efficiency is

affected by the presence of the ortho substituent with

respect to the chlorine atom. Indeed in the case of

complex 2d , the carbonylation product was isolated in

only 26% yield (Table 6, entry 7). It is worthy to note

that complex 2c reacting with Bu₃SnH did not allow the

formation of the expected carboxaldehyde (Table 6,

entry 8). We have not yet succeeded in the preparation

of the aldehyde by changing the hydride source.

The regioisomer η⁵-(2-chlorocyclohexadienyl)Mn(CO)₃

3a reacted much slower with ThSnBu and gave the

corresponding ketone 19 in 70% yield after 2 days (eq

11).

The same strategy applied to vinylstannane could

lead to ene-ones. Thus, carbonylation of complex 2c was

performed in the presence of tributylstyrylstannane in

THF using the same catalytic system. Complex 25 was

isolated as Z and E isomers in 27 and 28% yield,

respectively (1:1 ratio) (eq 13).

We then tried the substitution of the chlorine atom

by carbon- or heteroatom-based nucleophiles after the

palladium oxidative addition. Such reactions performed

with aryliodide or bromide and more recently with aryl

chloride are reported in the literature as requiring the

use of an elaborated catalytic system with bulky and

electron-rich ligands.^19-21In our case, we investigated

the formation of a C-C bond between an sp²carbon of

the cyclohexadienyl moiety and an sp³carbon of a

nucleophile. Before paying attention to Pd-catalyzed

processes, we ascertained that this reaction could not

be achieved by direct nucleophilic substitution. It has

As the carbonylation process may involve the acylpal-

ladate species B (eq 10), these reactions could be

extended to carboxylic acid derivatives by trapping

intermediate B with alcohols, amines, and thiols (Table

7). PhOH as well as MeOH reacted with complex 2c in

basic media to afford esters 20 in 71% yield and 21

(Table 7, entries 1 and 2). This latter complex exhibited

a high degree of unstability and was used without any

purification for further reactions. Carbonylation in the

presence of morpholine and p-tolylthiol led to amide 22

and thioester 23 in 48 and 22% yield, respectively (Table

7, entries 3 and 4).

(19) Fox, J . M.; Huang, X.; Chieffi, A.; Buchwald, S. L. J . Am. Chem.

Soc. 2000, 122, 1360, and references therein.

(20) Moradi, W. A.; Buchwald, S. L. J . Am. Chem. Soc. 2001, 123,

7996, and references therein.

(21) Lee, S.; Beare, N. A.; Hartwig, J . F. J . Am. Chem. Soc. 2001,

123, 8410.

1904 Organometallics, Vol. 22, No. 9, 2003

Auffrant et al.

been well established^5cthat stabilized anions add to

unsubstituted η⁵-(cyclohexadienyl)Mn(CO)₃complexes

to give cyclohexadienes. We thought that in the presence

of a leaving group (for example Cl^-) a substitution might

take place. Unfortunately, using 2-bromomethylpro-

panoate or 2-isobutyronitrile anion as nucleophile and

complex 2a or 2c as substrate, no reaction took place

(eq 14).

Ta ble 8. Am in a tion of

η⁵-(1-Ch lor ocycloh exa d ien yl)Mn (CO)₃Com p lexes

complex

(yield %)

entry

R¹,R

H, H

complex

HNR₂

1

2

3

4

5

6

7

8

9

2a

2b

2c

2e

2f

2c

2b

morpholine

HNEt₂

27a (84)

H, H

4-Me, H

27b (76)

27c (90)

27e

27f (55)

28 (84)

4-OMe, H

2-OMe, H

4-OMe, 6-Ph

4-OMe, H

4-Me, H

H₂NCH(CH₃)Ph

H₂N(C₆H₄)OMe

29 (42)

To overcome this hurdle, a Pd-catalyzed alternative

strategy was envisioned and, in particular, could the

same catalytic system Pd₂dba₃/AsPh₃be used to solve

the problem encountered during direct substitution?

at 60 °C gave the expected nitrile compound 26 after

8 h³⁰(eq 16).

We used nucleophiles such as anions of malonitrile

and cyclohexanone, whose arylation has been reported

in the literature.^19,20,22-27Reaction of complex 2c with

malonitrile in the presence of NaH and the catalytic

system Pd₂dba₃/AsPh₃at room temperature or at reflux

failed. In the case of cyclohexanone two different bases

were tested to generate the enolate: BuONa or LDA.

In both cases under THF reflux no coupling product was

obtained (eq 15).

We next turned our attention to N-, O-, S-, and

P-based nucleophiles.³³Results of amination reaction

with η⁵-(chlorocyclohexadienyl)Mn(CO)₃complexes are

gathered in Table 8. Reaction of complex 2a with

morpholine in the presence of Cs₂CO₃and the catalytic

system yielded complex 27a in 84% yield (Table 8, entry

1). No reaction took place when the same reaction was

conducted in the absence of a catalytic Pd system.

Extending this strategy to various substituted η⁵-

(chlorocyclohexadienyl)Mn(CO)₃complexes 2, we stud-

ied the influence of substituents R¹and R on the

catalytic process. We observed that whatever the nature

of R¹and R, the reaction was efficient, providing that

R¹was a para substituent (entries 2, 3, 4, 6). Indeed

when R¹) 2-OMe, no reaction was observed (entry 5).

Reaction took place even when C₆was substituted by a

phenyl group (entry 6).

Complex 2c underwent coupling reaction with acyclic

secondary amine (entry 7). This strategy could also be

extended to primary amines but only in the case of

aromatic amine such as anisidine (entry 9). In the case

of methylbenzylamine a mixture of products impossible

to analyze was obtained (entry 8).

The same reactions were performed with O-, S-, and

P-based nucleophiles (Table 9). Preformed sodium phe-

nolate and isoamylate reacted with complex 2c to afford

ethers 30 and 31 in 31 and 38% yield, respectively

(Table 9, entries 1, 2).

t

We then turned our attention to the Negishi reaction,

where we were first interested in introducing a benzyl

substituent. Benzylzinc bromide was prepared following

literature procedure.²⁸Reaction of complex 2c and zinc

reagent at THF reflux did not allow the isolation of a

coupling product. Even the more nucleophilic methyl-

propanoatezinc iodide gave no reaction after several

days at reflux in THF.

Finally a nitrile function could be introduced in an

η⁵-(cyclohexadienyl)Mn(CO)₃, by a palladium-catalyzed

nucleophilic substitution of chlorine by nitrile.²⁹Indeed

potassium nitrile in the presence of the catalytic

system (Pd₂dba₃/AsPh₃) and 18c6 crown ether in DMF

(22) Uno, M.; Seto, K.; Takahashi, S. J . Chem. Soc., Chem. Commun.

1984, 932.

(23) Shaughnessy, K. H.; Hamann, B. C.; Hartwig, J . P. J . Am.

Chem. Soc. 1998, 63, 6546.

(24) Palucki, M.; Buchwald, S. L. J . Am. Chem. Soc. 1997, 119, 1108.

(25) Hamann, B. C.; Hartwig, J . F. J . Am. Chem. Soc. 1997, 119,

12382.

(26) Ahnman, J .; Wolfe, J . P.; Troutman, M. V.; Palucki, M.;

Buchwald, S. L. J . Am. Chem. Soc. 1998, 120, 1918.

(27) Kawatsura, M.; Hartwig, J . F. J . Am. Chem. Soc, 1999, 121,

1473.

Thioethers 32 and 33 could also be synthesized under

the same reaction conditions using either aliphatic or

aromatic thiolates (Table 9, entries 3-5, 7). As we

(30) This compound could not be isolated because of its sensitivity

to silica; this is the reason it was used without purification for

rearomatisation.

(31) Xu, Y.; Li, Z.; Xia, J .; Guo, H.; Huang, Y. Synthesis 1984, 781.

(32) Prim, D.; Campagne, J . M.; J oseph, D.; Andrioletti, B. Tetra-

hedron 2002, 58, 2041.

(28) Rottla¨nder, M.; Knochel, P. Tetrahedron Lett. 1997, 38, 1749.

(29) Sundermeier, M.; Zapf, A.; Beller, M.; Sans, J . Tetrahedron Lett.

2001, 421, 6707.

(33) Auffrant, A.; Prim, D.; Rose-Munch, F.; Rose, E.; Vaissermann,

J . Organometallics 2002, 21, 3500.

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1905

Ta ble 9. Su bstitu tion of

η⁵-(1-Ch lor ocycloh exa d ien yl)Mn (CO)₃Com p lexes

by Eth er , Th io-eth er , P h osp h in e Oxid e, a n d

P h osp h in o Gr ou p s

F igu r e 2. ORTEP views of complex 23 (thermal ellipsoids

are at 30% probability).

complex

(yield %)

entry

R¹, R

complex

NuH

PhOH

isoamylOH

C₅H₁₄SH

p-tolylSH

HP(O)(OEt)₂

HP(O)(Ph)₂

HP(Ph)₂

1

2

3

4

5

6

7

8

4-OMe, H

H, H

4-OMe, H

2-OMe, H

4-OMe, Ph

4-OMe, H

2c

2a

2c

2e

2f

2c

30 (31)

31 (38)

32 (73)

33a (86)

33c (93)

33e

33f (88)

34 (77)

35 (43)

36 (64)

9

10

already observed with amines, the presence of an ortho

substituent precluded any reaction (entry 6), whereas

a substituent at C₆did not decrease the reaction

efficiency (entry 7). Introduction of P-based nucleophiles

was achieved using triethylamine as a base instead of

NaH as previously described.³¹Derivatives of diethyl

phosphite 34, diphenyl phosphine oxide 35, and diphen-

ylphosphine 36 were isolated in 77, 43, and 64% yield

(entries 8-10). In the case of complex 35, performing

the reaction in DMF at 50 °C instead of THF reflux

increased the yield (43% vs 36%). Thus the preparation

of unprecedented η⁵-(1-Nu-cyclohexadienyl)Mn(CO)₃com-

plexes was realized by an overall palladium-catalyzed

substitution of the chlorine atom. Since electron-releas-

ing groups exclusively direct meta addition (eq 17, path

b), such complexes cannot be prepared by hydride

F igu r e 3. ORTEP views of complex 33f (thermal ellipsoids

are at 30% probability).

addition onto η⁶-(Nu-arene)Mn(CO)₃(eq 17, path a).

+

tricarbonylmanganese complexes 23 and 33f were grown

in a diethyl ether/hexane mixture (Figures 2, 3 and

Table 10). Some selected bond lengths and dihedral

angles are presented in Table 11 as well as those of

complexes 5b^9cand 33c³³(Figure 4) for comparison. Two

important features can be emphasized. First they

generally confirm the η⁵structure of the coupling

product: we observe, as usually described,^34-37five

coplanar sp²carbons, while the remaining sp³carbon

is located out of this plane away from the metal. The

dihedral angles between [C₁C₆C₅] and [C₁C₂C₃C₄C₅]

planes reported in Table 11 are in good agreement with

literature data (except for 33c, vide infra).

In our case, the use of a Buchwald-Hartwig type

strategy starting from η⁵-(1-Cl-cyclohexadienyl)Mn(CO)₃

complexes gave a selective access to η⁵-(1-Nu-cyclohexa-

dienyl)Mn(CO)₃complexes (eq 17, path c).

The second point concerning X-ray structures pre-

sented in Figures 2 and 3 is the evidence of the

regioselective “ipso” process of the Pd-catalyzed reaction.

Indeed, the incoming R²substituent is located at C₁,

which previously bore the chlorine atom. For all these

structures the conformation of the Mn(CO)₃tripod is

in agreement with what is usually observed: the sp³

Moreover, in contrast with organic compounds series

which require a sophisticated catalytic system,³²syn-

thesis of η⁵-(cyclohexadienyl)Mn(CO)₃bearing a donor

group at the end of the π-system was achieved by

palladium-catalyzed reactions using the same nonelabo-

rated catalytic system Pd₂dba₃/AsPh₃.³³

(34) Lee, T. Y.; Bae, H. K.; Chung, Y. K.; Hallows, W. A.; Sweigart,

D. A. Inorg. Chim. Acta 1994, 224, 147.

(35) Dullaghan, C. A.; Carpenter, G. B.; Sweigart, D. A. Chem. Eur.

J . 1997, 3, 75.

(36) Balssa, F.; Gagliardini, V.; Lecorre-Susanne, C.; Rose-Munch,

F.; Rose, E.; Vaissermann, J . Bull. Soc. Chem. 1997, 134, 537.

(37) 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.

X-r a y An a lysis of th e η⁵-(1-R²-Cycloh exa d ien yl)-

Mn (CO)₃Com p lexes. X-ray studies were undertaken

for each type of coupling products. Crystals of η⁵-

1906 Organometallics, Vol. 22, No. 9, 2003

Ta ble 10. Cr ysta l Da ta for 23, 33f, 40c, a n d 44

Auffrant et al.

23

33f

40c

44

formula

fw (g mol^-1

a (Å)

b (Å)

c (Å)

R (deg)

â (deg)

γ (deg)

V (Å³)

Z

C

398.3

₁₈H₁₅MnO₅S

C₂₃H₁₉MnO₄S

446.39

C_16.5H₁₃BF₄MnO_5.5

473.07

21.279(19)

14.729(4)

13.782(4)

90

113.86(6)

90

S

C₁₆H₁₆BF₄MnO₅Si

458.12

)

7.019(7)

14.076(19)

19.066(16)

72.55(10)

79.45(7)

89.85(9)

1764(4)

4

9.544(2)

9.944(2)

12.405(2)

101.63(1)

109.21(2)

103.93(2)

1027.2(4)

2

10.481(4)

18.840(4)

10.618(2)

90

93.74(3)

90

3950(4)

8

2092(1)

4

cryst syst

triclinic

P1h

triclinic

P1h

monoclinic

C2/c

8.05

1.59

monoclinic

P2₁/a

7.2

1.45

ω/2θ

0.8 + 0.345 tan θ

1-26

0,12; 0,23; -13,13

4467

4093 (R_int) 0.01)

2384 (I > 3σ(I))

0.0534

space group

abs µ (cm^-1

)

8.56

7.4

density F (g cm^-3

scan type

)

1.50

ω/2θ

1.44

ω/2θ

scan range (deg)

θ limits (deg)

h,k,l limits

0.8 + 0.345 tan θ

1-25

0,8; -16,16; -22,22

6768

6211 (R_int) 0.05)

3187 (I > 3σ(I))

0.0634

0.8 + 0.345 tan θ

1-28

0.8 + 0.345 tan θ

1-25

0,12; -13,12; -16,15

0,25; 0,17; -16,14

no. data collected

no. unique data

no. data used

R^a

5236

3789

4942 (R_int) 0.02)

4053 (I > 3σ(I))

0.0369

3475 (R_int) 0.04)

1579 (I > 3σ(I))

0.11

b

R_w

0.0730

0.0455

0.13

0.0639

GOF

1.08

1.04

1.08

1.07

no. variables

452

-0.85

1.04

264

-0.38

0.44

229

-0.73

1.37

255

-0.41

0.46

∆F_min(e Å^-3

)

∆F_max(e Å^-3

(shift/esd)_max

0.029

0.00077

0.179

0.057

a

b

2

R ) ∑|F_o| - |F_c|/∑|F_o|. R_w) [∑w(|F_o| - |F_c|)²/∑w|F_o| ]^1/2

.

the classical η⁵feature with five coplanar carbons is

observed. The phenyl substituent is almost orthogonal

to the cyclohexadienyl plane, making a dihedral angle

of 86°. The sulfur substituent forms an angle of 96° with

the cyclohexadienyl plane and of 79° with the phenyl

substituent.

The position of the p-S-tolyl ring is very different for

the two complexes. In 33f, the ring is orthogonal to the

[C₁, C₄, S] plane and oriented toward the Mn(CO)₃

moiety because of the presence of the sterically demand-

ing phenyl substituent at the sp³C₆carbon, and the

sulfur atom is pointing in the direction opposite the

manganese entity. On the contrary, in 33c, the tolyl ring

is oriented in the direction opposite the Mn(CO)₃group

and the sulfur atom is pointing toward the metal. This

orientation could favor some interactions of the sulfur

atom with the two symmetrical carbonyl groups (C₂₁-

O₂₁and C₂₂-O₂₂) and could induce the deviation ob-

served for C₂. It is worthy to note that, when the sulfur

atom is one carbon away from the metal entity like in

compound 23, no interaction is possible and no deforma-

tion of the η⁵-cyclohexadienyl plane is observed.

F igu r e 4. “High-heeled shoe” conformation complex 33c

and complex 5b.

Ta ble 11. Selected Bon d Len gth s (Å) a n d Dih ed r a l

An gles (d eg) of Com p lexes 5b, 23, 33c, a n d 33f

5b

23

33c

33f

Mn-C₁

2.268

2.138

2.120

2.154

2.203

40

2.173

2.117

2.148

2.204

2.224

40

2.172

2.385

2.153

2.198

2.2167

25

2.268

2.138

2.124

2.168

2.156

40

Mn-C₂

Mn-C₃

Mn-C₄

Mn-C₅

[C₁C₆C₅]/[C₁C₂C₃C₄C₅]

carbon is eclipsed by one Mn-CO bond.^34-37It is also

worthy to note that the Mn-C₃bond is the shortest Mn-

cyclohexadienyl bond length (except for complex 23).

The carbonyl function of 23 (Figure 2) is not in the

cyclohexadienyl plane but deviated by 18° toward the

Mn(CO)₃entity. The structure of 33c (Figure 4) is

particularly surprising since the five carbons of the

cyclohexadienyl moiety are not coplanar.³³Indeed car-

bons C₂and C₆are located out of the plane formed by

C₁, C₃, C₄, and C₅away from the metal. Dihedral angles

between [C₁, C₂, C₃] and [C₁, C₅, C₆] with [C₁, C₃, C₄,

C₅] planes have very close values: 19.8° for the first one

and 25.2° for the second. This has been viewed as a

π-allyl C₃, C₄, C₅σ-alkyl C₁derivative³⁸which might

be represented by “a high-heeled shoe” conformation.

This unprecedented structure is not observed for 33f

(Figure 3), which differs from 33c by the presence of

a phenyl substituent on the sp³carbon. In this case,

Syn th esis of Novel Ca tion ic η⁶-(Ar en e)Mn (CO)₃

+

Com p lexes. As the functionalizations presented in the

aforementioned section preserved the manganese frag-

ment and kept the methylene carbons intact, all the

conditions were gathered to try the rearomatization of

the new η⁵complexes by exo-hydride abstraction. We

first focused on the preparation of cationic η⁶-(arene)-

Mn(CO)₃⁺complexes conjugated with an aromatic sys-

tem, a double or a triple bond. Such compounds are

difficult or impossible to prepare selectively by direct

complexation. For example, it is known that metalation

(38) σ,π-Cyclohexenyl complex reported by, Pike, R. D.; Ryan, W.

J .; Lennhof, N. S.; Van Epp, J .; Sweigart, D. A. J . Am. Chem. Soc.

1990, 112, 4798, is similar to that obtained here. But in this structure

the carbon C₂is effectively a sp³carbon not bonded to the metal center.

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1907

Ta ble 12. Syn th esis of New η⁶-(Ar en e)Mn (CO)₃

+

Com p lexes

complex

(yield %)

entry

complex

R¹, R²

4-OMe, Th

1

5c

37 (93)

2

3

4

5

6

7

8

9

4-OMe, CtCPh

4-OMe, CHdCHPh

4-Me, COTh

38 (96)

12E

16b

16c

20

21

22

39E (94)

40b (95)

40c (95)

41 (70)

42 (77, 2 steps)

43 (85)

4-OMe, COTh

F igu r e 5. ORTEP views of complex40c (thermal ellipsoids

are at 30% probability).

4-OMe, CO₂Ph

4-OMe, CO₂Me

4-OMe, CO₂N[(CH₂)₂]₂O

4-OMe, COCtCSiMe₃

CN

24

26

44 (65)

45 (35, 2 steps)

10

of 2-phenylpyrrole gave exclusively 2-phenyl-(η⁵-pyrro-

lyl)tricarbonylmanganese³⁹and that phenylacetylene

could not be coordinated to the Mn(CO)₃entity.¹⁴We

were interested in preparing 2-thienyl-(η⁶-anisole)Mn-

(CO)₃⁺by rearomatization of η⁵(1-thienyl-4-methoxycy-

-

clohexadienyl)Mn(CO)₃5c. The reaction with CPh₃⁺BF₄

proceeded smoothly to deliver complex 37 in 93% yield

(Table 12, entry 1). Similarly, complexes 9 and 12E were

subjected to rearomatization upon hydride abstraction,

and complexes 38 and 39E were isolated in 96 and 94%

yield, respectively (Table 12, entries 2, 3).

Taking advantage of these precedents, we have

turned our attention toward the synthesis of resonance

withdrawing group substituted cationic complexes which

were never described in the literature since the low

electronic density of the aromatic cycle prevents any

direct complexation.¹⁴Even disrupting the electron

transfer to the acceptor group by protecting the electron-

withdrawing substituent precludes metalation.¹⁴The

coexistence of two strong electron-withdrawing groups,

the carbonyl or the nitrile function and the metal entity

F igu r e 6. ORTEP views of complex 44 (thermal ellipsoids

are at 30% probability).

Ta ble 13. H₂a n d H₃Ch em ica l Sh ifts in

+

η⁶-(EWG-a r en e)Mn (CO)₃Com p lexes

+

Mn(CO)₃on the arene, was an interesting challenge.

∆δ )

Complexes 16b and 16c reacted with triphenylcarbe-

nium tetrafluoroborate to deliver complexes 40b and

40c in excellent yield (95%) (Table 12, entries 4, 5). No

problem of stability during the reaction or for the

isolation of the products was observed. Cationic car-

boxylic acid derivatives (ester and amide) were obtained

in the same way (Table 12, entries 6-8), even in the

case of complex 42, whose η⁵intermediate could not be

isolated after the coupling reaction (entry 7). Yne-one

24 was successfully subjected to the same conditions to

yield complex 44 (entry 9). Complex 45, arising from

hydride abstraction performed on the crude mixture

containing 26 (entry 10), was obtained in 35% yield for

the two steps. Thus, for the first time, it was possible

to undertake studies on the tripod conformation of η⁶-

complex

R¹

4-OMe COTh

4-Me COTh

4-OMe CO₂Ph

4-OMe CO₂Me

4-OMe CON[(CH₂)₂]O 7.43

4-OMe COCCSiMe₃

4-OMe CN

EWG

δ(H₂) δ(H₃) δ(H₂) - δ(H₃)

40b

40c

41

42

43

7.66

7.52

7.69

7.64

7.57

6.83

6.49

6.56

6.40

6.59

7.74

1.09

0.69

1.20

1.08

1.03

1.19

0.14

44

45

7.78

7.90

electron-donating group (R¹) OMe, Me): it induces a

positive charge on the C₂carbon and a negative one on

the C₃carbon (Table 13). As a consequence, proton H²

is deshielded whereas proton H³is shielded, leading to

noticeable values of ∆δ (up to 1.20 ppm versus an

average 0.40 ppm value for non-substituted complexes).

Such values of ∆δ are in good agreement with an anti-

eclipsed conformation of the Mn(CO)₃tripod with re-

spect to the electron-withdrawing group in solution

(Table 13).⁴⁰

+

(EWG-arene)Mn(CO)₃in solution by NMR and in the

solid state by X-ray analysis. In the case of the com-

plexes reported in Table 12, the difference of the

chemical shifts of H²and H³proton resonances is, as

expected, noticeable and can reach +1.2 ppm. This is

due to the electronic distribution created by a resonance-

withdrawing group (EWG ) COTh, CO₂Ph, CO₂Me,

CON[(CH₂)₂]O, COCCSiMe₃, CN) located para to an

The first study of the conformation of η⁶-(EWG-arene)-

+

Mn(CO)₃in the solid state was allowed by X-ray

analysis of complexes 40c (Figure 5) and 44 (Figure 6).

Selected bond lengths and angles are given in Table 14

(40) For chromium analogues see: (a) Hoffmann, R.; Hoffmann, P.

J . Am. Chem. Soc. 1976, 98, 598. (b) Rose-Munch, F.; Rose, E. Curr.

Org. Chem. 1999, 3, 445.

(39) Coleman, K. J .; Davies, C. S.; Gogan, N. J . J . Chem. Soc., Chem.

Commun. 1970, 1414.

1908 Organometallics, Vol. 22, No. 9, 2003

Auffrant et al.

These first structures of η⁶-(EWG-arene)Mn(CO)₃

+

complexes showed an anti-eclipsed conformation of the

tripod with respect to the electron-accepting group. Such

orientation was until now just a hypothesis by analogy

with tricarbonylchromium complexes.

Con clu sion

F igu r e 7. Complex 41 and complex 40Cr .

We successfully developed a general palladium-

catalyzed strategy for unprecedented functionalization

of η⁵-(cyclohexadienyl)Mn(CO)₃complexes. In particular,

η⁵complexes bearing either electron-donating or -with-

drawing groups at the terminus of the π-system were

obtained in high yield. X-ray analysis of four η⁵com-

plexes was also presented. The method of functional-

ization preserving the methylene exo fragment allows

the rearomatization of the η⁵complex by hydride

Ta ble 14. Selected Bon d Len gth s (Å) a n d Dih ed r a l

An gles (d eg) of Com p lexes 40c, 41a , 41b, 44, 40Cr

40c

41a

41b

44

40Cr

Mn-C₁

Mn-C₂

Mn-C₃

Mn-C₄

Mn-C₅

Mn-C₆

R (deg)

â (deg)

γ (deg)

2.17

2.22

2.31

2.21

2.16

9

2.154

2.171

2.199

2.273

2.20

2.153

8

2.161

2.186

2.226

2.266

2.186

2.153

5

2.148

2.151

2.203

2.298

2.205

2.153

6

2.181

2.206

2.238

2.282

2.242

2.181

21

+

abstraction, leading to new cationic η⁶-(arene)Mn(CO)₃

6

9

5

2

17

14

6

5

22

complexes. The first conformational studies of cationic

arene tricarbonylmanganese complexes substituted by

resonance-withdrawing groups were conducted in solu-

tion and in the solid state, evidencing an anti-eclipsed

conformation with respect to the carbon bearing the

electron acceptor substituents.

together with those of complexes 41¹⁸and 40Cr ^9b

(Figure 7), the related isoelectronic, neutral tricarbonyl-

chromium complex, analogous to 40c.

The cation displays the well-known piano stool con-

formation found in half-sandwich tricarbonyl com-

plexes.⁴¹The arene-ring and C₇carbon atoms were

found almost coplanar. The Mn-C(ring) bond lengths

ranging from 2.15 to 2.30 Å (average 2.20 Å) are a bit

shorter than the corresponding distances in complex

40Cr (average 2.23 Å).⁴²The positive charge on the

manganese atom results in a little contraction of the

metal ring average distances. Moreover, comparison of

the bond lengths collected in Table 14 shows that Mn-

C₁, Mn-C₂, and Mn-C₆distances are shorter than Mn-

C₃, Mn-C₄, and Mn-C₅ones. This is due to the

manganese entity displacement from the center of the

six arene carbons toward the C₁carbon substituted by

the carbonyl function.⁴³

The conformation of the tripod is, for each complex,

almost anti-eclipsed. Deviation of R, â, and γ angles

reported in Table 14 are much smaller than those

corresponding to complex 40Cr , whose conformation has

been reported as staggered.^9b

For complex 40c (Figure 5), the carbonyl function is

out of the plane of the arene ring, pointing toward the

metal with a dihedral angle of 31°. For the chromium

complex 40Cr (Figure 7), the carbonyl function pointed

in the direction opposite the Cr(CO)₃moiety.^9b

In the X-ray analysis of complex 41¹⁸we observed two

independent molecular cations differing by the confor-

mation of the tricarbonylmanganese tripod. In one of

these complexes (represented in Figure 7) the structure

showed an anti-eclipsed conformation with respect to

the ester group, whereas in the other one, a slightly

deviated conformation was observed. For the yne-one

complex 44 (Figure 6), the methoxy group lies in the

arene ring plane, whereas C₈, C₉carbon atoms and the

silicon atom are out of this plane, with respective

distances of 0.11, 0.25, and 0.47 Å.

Exp er im en ta l Section

All reactions and manipulations were routinely performed

under a dry nitrogen atmosphere using Schlenk tube tech-

niques. THF was dried over sodium benzophenone ketyl and

distilled. Infrared spectra were measured on a Perkin-Elmer

1420 spectrometer. ¹H, ³¹P{¹H}, and ¹³C{¹H} NMR spectra

were obtained on

a Bruker AC200, AC400, or DRX500

spectrometer. Elemental analyses were performed by Le

service de Microanalyses de l’Universite´ Pierre et Marie Curie.

+

P r ep a r a tion of η⁶-(Ch lor oa r en e)Mn (CO)₃

: 1. Com-

plexes 1a ^4aand 1b-1e⁷were synthesized following procedures

already described in the literature.

P r ep a r a tion of η⁵-(Ch lor ocycloh exa d ien yl)Mn (CO)₃: 2

a n d 3. Complexes 2a ,b, 3a ,b^4a2c-e, and 3c-e⁷were prepared

by addition of AlLiH₄as already described.

Complex 2f was prepared by addition of phenylmagnesium

bromide, with an experimental procedure similar to that

described by Chung.^{11 1}H NMR (CDCl₃): 3.48 (3H, s, OMe),

3.56 (1H, dd, J ) 6.5 and 3 Hz, H₅), 4.49 (1H, dd, J ) 1.5 and

6.5 Hz, H_6endo), 5.21 (1H, dd, J ) 1.5 and 6 Hz, H₂), 5.55 (1H,

dd, J ) 6 and 3 Hz, H₃), 6.99 (2H, t, J ) 5 Hz, Ar H), 7.20

(3H, m, Ar H). ¹³C NMR (CDCl₃): 45.1 (C₅), 52.2 (C₆), 54.9

(OMe), 64.5 (C₃), 80.0 (C₁), 92.5 (C₂), 126.1 (Ar CH), 127.7 (Ar

CH), 128.6 (Ar CH), 141.7 (Ar C), 143.7 (C₄), 221.6 (CO(Mn)).

Anal. Calcd: C, 53.63; H, 3.38. Found: C, 53.45; H, 3.20.

St ille Ar yla t ion of η⁵-(Ch lor ocycloh exa d ien yl)Mn -

(CO)₃: 2 a n d 3. Typ ica l Ar yla tion P r oced u r e: P r ep a r a -

tion of Com p lex 4a . Pd₂dba₃(0.029 g, 0.03 mmol) and AsPh₃

(0.034 g, 0.11 mmol) were added successively to complex 2a

(0.081 g, 0.32 mmol) in 7 mL of anhydrous degassed DMF.

After 5 min at room temperature tributylstannylbenzene

(0.104 mL, 0.32 mmol) was introduced. The mixture was

stirred for 23 h at room temperature, poured into 50 mL of

cold ice water, and extracted twice with 30 mL of pentane.

The combined organic phases were washed with water (20

mL), dried over magnesium sulfate, filtered, and evaporated

under reduced pressure. The residue was then purified by flash

chromatography on silica gel (pentane) to afford complex 4a

in 52% yield. IR (CHCl₃): 1914, 2003 (CO(Mn)). ¹H NMR

(CDCl₃): 2.53 (1H, d, J ) 13 Hz, H_6exo), 3.19 (1H, t, J ) 6 Hz,

H₅), 3.28 (1H, dd, J ) 13 and 6 Hz, H_6endo), 5.02 (1H, t, J ) 6

Hz, H₄), 5.29 (1H, d, J ) 6 Hz, H₂), 5.98 (1H, t, J ) 6 Hz, H₃),

7.41 (5H, m, Ar H). ¹³C NMR (CDCl₃): 23.5 (C₆), 54.8 (C₅),

82.2 (C₃), 92.3 (C₂), 99.1 (C₄), 102.1 (C₁), 127.0 (Ar CH), 128.2

(41) Berndt, A. F.; Marsh, R. E. Acta Crystallogr. 1963, 16, 118.

(42) Muetterties, E. L.; Bleeke, J . R.; Wucherer, E. J .; Albright, T.

A. Chem. Rev. 1982, 82, 499.

(43) The same phenomena were observed for tricarbonylchromium

complexes, see: Djukic, J . P.; Rose-Munch, F.; Rose, E.; Vaissermann,

J . Eur. J . Inorg. Chem. 2000, 1295.

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1909

(Ar CH), 130.5 (Ar CH), 133.1 (Ar C), 222.7 (CO(Mn)). Anal.

Calcd: C, 61.24; H, 3.77. Found: C, 59.97; H, 3.84.

21.6 (Me), 30.1 (C₆), 51.0 (C₅), 70.7 (C₁), 74.9 (C₃), 95.8 (C₄),

115.1 (C₂), 121.9 (Ar CH), 124.8 (Ar CH), 128.1 (Ar CH), 133.2

(Ar C), 222.4 (CO(Mn)). Anal. Calcd: C, 53.51; H, 3.53.

Found: C, 53.6; H, 3.69.

6d (43%). IR (CHCl₃): 1919, 1997 (CO(Mn)). ¹H NMR

(CDCl₃): 1.88 (3H, s, Me), 2.38 (1H, d, J ) 13 Hz, H_6exo), 2.75

(1H, m, H_6endo), 2.99 (1H, m, H₅), 4.83 (1H, m, H₄), 6.01 (1H,

d, J ) 6 Hz, H₃), 6.97 (1H, d, J ) 4 Hz, Ar H), 7.19 (2H, m, Ar

H). ¹³C NMR (CDCl₃): 20.9 (Me), 31.8 (C₆), 52.2 (C₅), 74.3 (C₁),

81.3 (C₃), 90.2 (C₄), 112.2 (C₂), 121.6 (Ar CH), 123.9 (Ar CH),

126.3 (Ar CH), 132.4 (Ar C), 223.8 (CO(Mn)). Anal. Calcd: C,

53.51; H, 3.53. Found: C, 53.61; H, 3.74.

Performing the same reaction using SbPh₃instead of AsPh₃

allows the isolation of complex 4′a (20%) together with 4a

(60%). 4′a IR (CHCl₃): 1994, 2058 (CO(Mn)), 1600 (CO). ¹H

NMR (CDCl₃): 2.15 (1H, d, J ) 14 Hz, H_6exo), 3.41 (1H, dd, J

) 14 and 6 Hz, H_6endo), 3.51 (1H, dd, J ) 6 and 3 Hz, H₅), 5.09

(1H, t, J ) 3 Hz, H₄), 5.29 (1H, d, J ) 3 Hz, H₂), 5.98 (1H, t,

J ) 3 Hz, H₃), 7.44 (5H, m, Ar H). Anal. Calcd: C, 59.64; H,

3.44. Found: C, 59.63; H, 3.44.

Complex 4b was obtained by the same procedure using

AsPh₃as ligand in 45% yield. IR (CHCl₃): 1916, 1996 (CO-

1

(Mn)). H NMR (CDCl₃): 1.91 (3H, s, Me), 2.13 (1H, d, J ) 13

Su bstitu tion by Un sa tu r a ted Bon d s. Typ ica l Son o-

ga sh ir a Rea ction P r oced u r e: P r ep a r a tion of Com p lex

9. Pd₂dba₃(0.0178 g, 0.019 mmol) and AsPh₃(0.021 g, 0.068

mmol) were added successively to complex 2c (0.055 g, 0.195

mmol) in 6 mL of anhydrous degassed triethylamine. After 5

min at room temperature phenylacetylene (0.022 mL, 0.195

mmol) was introduced. The mixture was stirred for 4 h at 45

°C, poured into 20 mL of cold ice water, and extracted twice

with diethyl ether (20 mL). The combined organic phases were

washed with a saturated ammonium chloride solution (20 mL),

dried over magnesium sulfate, filtered, and evaporated under

reduced pressure. The residue was then purified by flash

chromatography on silica gel (petroleum ether/Et₂O, 90:10) to

afford complex 9 in 79% yield. IR (CHCl₃): 1950, 2018 (CO-

Hz, H_6exo), 3.04 (1H, m, H_6endo), 3.25 (1H, m, H₅), 5.22 (1H, d,

J ) 6 Hz, H₂), 5.82 (1H, d, J ) 6 Hz, H₃), 7.35 (5H, m, Ar H).

¹³C NMR (CDCl₃): 22.7 (Me), 32.5 (C₆), 52.1 (C₅), 76.2 (C₁),

94.0 (C₃), 95.8 (C₂), 110.3 (C₄), 127.9 (Ar CH), 128.4 (Ar CH),

130.1 (Ar CH), 133.1 (Ar C), 223.4 (CO(Mn)). Anal. Calcd: C,

62.35; H, 4.25. Found: C, 62.54; H, 4.01.

Arylation procedure performed with tributylstannylthio-

phene instead of tributylstannylbenzene afforded complexes

5. Complex 5a was isolated in 51% yield. IR (CHCl₃): 1915,

2000 (CO(Mn)). ¹H NMR (CDCl₃): 2.45 (1H, d, J ) 13 Hz,

H

_6exo), 3.21 (2H, m, H₅, H_6endo), 4.95 (1H, t, J ) 5 Hz, H₄), 5.25

(1H, d, J ) 5 Hz, H₂), 5.86 (1H, t, J ) 5 Hz, H₃), 6.86 (1H, d,

J ) 4 Hz, Ar H), 6.94 (1H, m, Ar H), 7.17 (1H, d, J ) 5 Hz, Ar

H). ¹³C NMR (CDCl₃): 28.7 (C₆), 51.2 (C₅), 77.6 (C₃), 94.5 (C₂),

97.2 (C₄), 103.1 (C₁), 122.6 (Ar CH), 125.1 (Ar CH), 128.0 (Ar

CH), 133.7 (Ar C), 226.1 (CO(Mn)). Anal. Calcd: C, 52.00; H,

3.00. Found: C, 52.12; H, 2.80.

1

(Mn)), 2208 (CtC). H NMR (CDCl₃): 2.46 (1H, d, J ) 13 Hz,

H

_6exo), 2.92 (1H, dd, J ) 6 and 13 Hz, H_6endo), 3.09 (1H, dd, J

) 6 and 2.5 Hz, H₅), 5.23 (1H, d, J ) 6 Hz, H₂), 5.79 (1H, dd,

J ) 2.5 and 6 Hz, H₃), 7.3 (5H, m, Ar H). ¹³C NMR (CDCl₃):

32.0 (C₆), 36.3 (C₅), 47.3 (C₁), 54.5 (OMe), 67.9 (C₃), 86.1 (C(Ct

C)), 90.2 (C(CtC)), 97.1 (C₂), 123.2 (Ar CH), 128.1 (Ar CH),

128.3 (Ar CH), 130.6 (Ar C), 143.2 (C₄), 220.2 (CO(Mn)). Anal.

Calcd: C, 62.08; H, 3.76. Found: C, 62.25; H, 4.02.

5b (48%). IR (CHCl₃): 1917, 1998 (CO(Mn)). ¹H NMR

(CDCl₃): 1.90 (3H, s, Me), 2.51 (1H, d, J ) 12 Hz, H_6exo), 3.15

(1H, d, J ) 6 Hz, H₅), 3.24 (1H, dd, J ) 6 and 12 Hz, H_6endo),

5.22 (1H, d, J ) 6 Hz, H₂), 5.74 (1H, d, J ) 6 Hz, H₃), 6.84

(1H, d, J ) 4 Hz, Ar H), 6.92 (1H, m, Ar H), 7.15 (1H, d, J )

4 Hz, Ar H). ¹³C NMR (CDCl₃): 21.9 (Me), 29.3 (C₆), 50.8 (C₅),

77.9 (C₃), 94.1 (C₂), 97.8 (C₄), 106.2 (C₁), 122.3 (Ar CH), 124.8

(Ar CH), 127.7 (Ar CH), 133.8 (Ar C), 223.2 (CO(Mn)). Anal.

Calcd: C, 53.51; H, 3.53. Found: C, 53.59; H, 3.75.

5c (78%). IR (CHCl₃): 1922, 1990 (CO(Mn)). ¹H NMR

(CDCl₃): 2.60 (1H, d, J ) 13 Hz, H_6exo), 3.10 (1H, m, H₅), 3.29

(1H, m, H_6endo), 3.51 (3H, s, OMe), 5.27 (1H, d, J ) 6 Hz, H₂),

5.76 (1H, d, J ) 6 Hz, H₃), 6.80 (1H, d, J ) 3.5 Hz, Ar H), 6.91

(1H, dd, J ) 3.5 and 4.5 Hz, Ar H), 7.14 (1H, d, J ) 4.5 Hz, Ar

H). ¹³C NMR (CDCl₃): 29.5 (C₆), 35.6 (C₅), 53.4 (OMe), 63.3

(C₁), 65.5 (C₃), 106.2 (C₂), 121.2 (Ar CH), 123.5 (Ar CH), 126.5

(Ar CH), 132.7(Ar C), 143.0 (C₄), 224.3 (CO(Mn)). Anal.

Calcd: C, 50.92; H, 3.36. Found: C, 50.80; H, 3.41.

The same procedure was applied for the preparation of 10a ,c

and 11. 10a (40%). IR (CHCl₃): 1935, 2025 (CO(Mn)), 2147

(CtC). ¹H NMR (CDCl₃): 0.15 (9H, s, Me), 2.23 (1H, d, J )

13 Hz, H_6exo), 2.77 (1H, dd, J ) 13 and 6 Hz, H_6endo), 3.20 (1H,

t, J ) 6 Hz, H₅), 4.84 (1H, d, J ) 5 and 6 Hz, H₄), 5.12 (1H, d,

J

) 5.5 Hz, H₂), 5.80 (1H, t, J ) 5.5 Hz, H₃). ¹³C NMR

(CDCl₃): 0.10 (Me), 29.8 (C₆), 51.6 (C₅), 66.0 (C₁), 78.9 (C₃),

90.8 (C(CtC)), 97.4 (C₂), 100.6 (C₄), 106.7 (C(CtC)), 222.1 (CO-

(Mn)). Anal. Calcd: C, 53.50; H, 4.81. Found: C, 53.28; H, 4.67.

10c (78%). IR (CHCl

₃): 1938, 2025 (CO(Mn)), 2150 (CtC).

¹H NMR (CDCl₃): 0.12 (9H, s, Me), 2.33 (1H, d, J ) 13 Hz,

H

_6exo), 2.83 (1H, dd, J ) 13 and 6 Hz, H_6endo), 2.97 (1H, d, J )

6 Hz, H

₅), 3.76 (3H, s, OMe), 5.13 (1H, d, J ) 5 Hz, H₂), 5.70

(1H, d, J ) 5 Hz, H

₃). ¹³C NMR (CDCl₃): 0.13 (Me), 31.6 (C₆),

5d (53%). IR (CHCl₃): 1917, 1998 (CO(Mn)). ¹H NMR

(CDCl₃): 2.02 (3H, s, Me), 2.60 (1H, d, J ) 12 Hz, H_6exo), 3.06

(2H, m, H_6endo, H₅), 4.87 (1H, t, J ) 5 Hz, H₄), 5.75 (1H, d, J )

5 Hz, H₃), 6.82 (1H, d, J ) 4 Hz, Ar H), 6.94 (1H, m, Ar H),

7.20 (1H, d, J ) 5 Hz, Ar H). ¹³C NMR (CDCl₃): 19.6 (Me),

31.7 (C₆), 49.7 (C₅), 75.1 (C₂), 79.5 (C₃), 94.7 (C₄), 105.4 (C₁),

123.8 (Ar CH), 125.7 (Ar CH), 127.6 (Ar CH), 132.6 (Ar C),

222.2 (CO(Mn)). Anal. Calcd: C, 53.51; H, 3.53. Found: C,

53.57; H, 3.66.

36.2 (C₅), 46.1 (C₁), 54.4 (OMe), 68.1 (C₃), 90.9 (C(CtC)), 97.6

(C₂), 106.1 (C(CtC)), 143.3 (C₄), 221.2 (CO(Mn)). Anal. Calcd:

C, 52.32; H, 4.98. Found: C, 52.49; H, 4.74.

11 (95%). ¹H NMR (CDCl₃): 1.87 (3H, s, Me), 2.39 (1H, d, J

) 13 Hz, H_6exo), 2.91 (1H, dd, J ) 13 and 6 Hz, H_6endo), 3.11

(1H, d, J ) 6 Hz, H₁), 5.16 (1H, d, J ) 5 Hz, H₄), 5.74 (1H, d,

J ) 5 Hz, H₃), 7.29 (3H, m, Ar H), 7.38 (2H, m, Ar H). ¹³C

NMR (CDCl₃): 21.3 (Me), 29.9 (C₆), 45.3 (C₅), 51.7 (C₁), 78.9

(C₃), 84.8 (C(CtC)), 89.6 (C(CtC)), 97.8 (C₄), 111.3 (Ar C),

122.2 (C₂), 127.0 (Ar CH), 127.2 (Ar CH), 130.5 (Ar CH), 221.3

(CO(Mn)). Anal. Calcd: C, 65.07; H, 3.94. Found: C, 65.25;

H, 4.21.

Similar arylation reaction starting from complexes 3 led to

1

complexes 6. 6a (58%). IR (CHCl₃): 1915, 2000 (CO(Mn)). H

NMR (CDCl₃): 2.17 (1H, d, J ) 14 Hz, H_6exo), 2.83 (1H, m,

H

_6endo), 2.99 (1H, m, H₅), 3.42 (1H, m, H₁), 4.93 (1H, m, H₄),

Typ ica l Stille Rea ction P r oced u r e: P r ep a r a tion of

Com p lex 8. Pd₂dba₃(0.014 g, 0.016 mmol) and AsPh₃(0.017

g, 0.056 mmol) were added successively to complex 2a (0.040

g, 0.16 mmol) in 5 mL of anhydrous degassed DMF. After 5

min at room temperature tributylstannylethynylbenzene (0.056

mL, 0.16 mmol) was introduced. The mixture was stirred half

an hour, cold ice water (20 mL) was then added, and the

reaction mixture was extracted twice with pentane (20 mL).

The combined organic phases were washed with water (3 ×

20 mL) and a saturated ammonium chloride solution (20 mL),

dried over magnesium sulfate, filtered, and evaporated under

6.35 (1H, dd, J ) 6 and 3 Hz, H₃), 6.97 (1H, d, J ) 4 Hz, Ar

H), 7.22 (2H, m, Ar H). ¹³C NMR (CDCl₃): 29.7 (C₆), 52.4 (C₅),

77.2 (C₃), 78.0 (C₁), 92.7 (C₄), 116.8 (C₂), 122.1 (Ar CH), 124.5

(Ar CH), 127.5 (Ar CH), 132.9 (Ar C), 223.0 (CO(Mn)). Anal.

Calcd: C, 52.00; H, 3.00. Found: C, 52.25; H, 3.05.

6b (30%). IR (CHCl₃): 1920, 1998 (CO(Mn)). ¹H NMR

(CDCl₃): 1.61 (3H, s, Me), 2.35 (1H, d, J ) 14 Hz, H_6exo), 2.76

(1H, dd, J ) 6 and 14 Hz, H_6endo), 3.36 (1H, d, J ) 6 Hz, H₁),

4.65 (1H, d, J ) 5 Hz, H₄), 6.18 (1H, d, J ) 5 Hz, H₃), 6.95

(1H, d, J ) 4 Hz, Ar H), 7.21 (2H, m, Ar H). ¹³C NMR (CDCl₃):

1910 Organometallics, Vol. 22, No. 9, 2003

Auffrant et al.

reduced pressure. The residue was then purified by flash

chromatography on silica gel (petroleum ether/Et₂O, 90:10) to

afford complex 8 in 91% yield. IR (CHCl₃): 1947, 2022 (CO-

(1H, d, J ) 15 Hz, H(CdC)), 6.90 (1H, d, J ) 15 Hz, H(CdC)),

7.12 (2H, d, J ) 7.5 Hz, Ar H), 7.23 (1H, t, J ) 7.5 Hz, Ar H),

7.38 (2H, t, J ) 7.5 Hz, Ar H). ¹³C NMR (CDCl₃): 26.7 (C₆),

37.3 (C₅), 54.7 (OMe), 59.2 (C₁), 69.4 (C₃), 98.3 (C₂), 114.0

(C(CdC)), 121.7 (Ar CH), 125.8 (Ar CH), 129.5 (Ar CH), 144.4

(C₄), 150.4 (C(CdC)), 150.8 (Ar C), 165.2 (CO), 220.1 (CO(Mn)).

Anal. Calcd: C, 57.89; H, 3.83. Found: C, 57.69; H, 4.06.

15 (13%). IR (CHCl₃): 1937, 2018 (CO(Mn)), 1722 (CO), 1623

(CdC). ¹H NMR (CDCl₃): 1.28 (3H, t, J ) 7 Hz, Me), 2.24 (1H,

d, J ) 13 Hz, H_6exo), 2.91 (1H, dd, J ) 6 and 13 Hz, H_6endo),

3.12 (1H, d, J ) 6 Hz, H₅), 3.49 (3H, s, OMe), 4.18 (2H, q, J )

7 Hz, CH₂), 5.10 (1H, d, J ) 6 Hz, H₂), 5.63 (1H, d, J ) 15.5

Hz, H(CdC)), 5.82 (1H, d, J ) 6 Hz, H₃), 6.73 (1H, d, J ) 15.5

Hz, H(CdC)). ¹³C NMR (CDCl₃): 14.4 (Me), 26.7 (C₆), 37.1 (C₅),

54.6 (OMe), 60.1 (C₁), 60.4 (CH₂), 68.8 (C₃), 97.7 (C₂), 115.4

(C(CdC)), 144.3 (C₄), 148.1 (C(CdC)), 166.8 (CO), 221.5 (CO-

(Mn)). Anal. Calcd: C, 52.04; H, 4.37. Found: C, 52.19; H, 4.45.

Typ ica l Ca r b on yla t ion P r oced u r e: P r ep a r a t ion of

16b. Pd₂dba₃(0.023 g, 0.025 mmol) and AsPh₃(0.027 g, 0.088

mmol) were added successively to complex 2b (0.067 g, 0.25

mmol) in 10 mL of anhydrous THF. Carbon monoxide was

pulled through the reaction mixture, and tributylstannylthio-

phene (0.033 mL, 0.25 mmol) was introduced. The solution was

stirred for 2.5 h at reflux, cold ice water (15 mL) was then

added, and the reaction mixture was extracted twice with

diethyl ether (20 mL). The combined organic phases were

washed with water (20 mL), dried over magnesium sulfate,

filtered, and evaporated under nitrogen flush. The residue was

then purified by flash chromatography on silica gel (petroleum

ether/Et₂O, 80:20) to deliver complex 16b in 90% yield. IR

1

(Mn)), 2203 (CtC). H NMR (CDCl₃): 2.41 (1H, d, J ) 13 Hz,

H

_6exo), 2.94 (1H, dd, J ) 13 and 6 Hz, H_6endo), 3.23 (1H, d, J )

6 Hz, H₅), 4.93 (1H, dd, J ) 5 and 6 Hz, H₄), 5.22 (1H, d, J )

5 Hz, H₂), 5.89 (1H, t, J ) 5 Hz, H₃), 7.30-7.42 (5H, m, Ar H).

¹³C NMR (CDCl₃): 29.7 (C₆), 52.5 (C₅), 78.8 (C₁), 87.3 (C₃), 95.0

(C(CtC)), 97.3 (C₂), 100.2 (C₄), 103.2 (C(CtC)), 128.2 (Ar CH),

128.4 (Ar CH), 131.7 (Ar CH), 134.8 (Ar C), 219.6 (CO(Mn)).

Anal. Calcd: C, 64.17; H, 3.48. Found: C, 64.52; H, 3.37.

Preparation of complexes 12Z-E and 13Z-E was achieved

with the same protocol substituting tributylstannylethynyl-

benzene by tributylstyrylstannane. 12Z (27%). IR (CHCl₃):

1935, 2015 (CO(Mn)), 1619 (CdC). ¹H NMR (CDCl₃): 2.12 (1H,

d, J ) 13 Hz, H_6exo), 2.37 (1H, dd, J ) 6 and 13 Hz, H_6endo),

2.80 (1H, dd, J ) 2.5 and 6 Hz, H₅), 3.41 (3H, s, OMe), 4.84

(1H, d, J ) 5.5 Hz, H₂), 5.48 (1H, d, J ) 11 Hz, H(CdC)), 5.66

(1H, dd, J ) 5.5 and 2.5 Hz, H₃), 6.42 (1H, d, J ) 11 Hz, H(Cd

C)), 7.30 (5H, m, Ar H). ¹³C NMR (CDCl₃): 31.3 (C₆), 36.7 (C₅),

68.5 (C₁), 55.5 (OMe), 67.5 (C₃), 86.1 (C(CdC)), 90.2 (C(Cd

C)), 95.9 (C₂), 128.1 (Ar CH), 128.9 (Ar CH), 133.1 (Ar CH),

139.9 (Ar C), 144.3 (C₄), 222.9 (CO(Mn)). Anal. Calcd: C, 61.73;

H, 4.32. Found: C, 61.66; H, 4.40. 12E (36%). IR (CHCl₃):

1933, 2011 (CO(Mn)), 1622 (CdC). ¹H NMR (CDCl₃): 2.36 (1H,

d, J ) 13 Hz, H_6exo), 3.09 (1H, dd, J ) 13 and 6 Hz, H_6endo),

3.24 (1H, d, J ) 6 Hz, H₅), 3.52 (3H, s, OMe), 4.87 (1H, d, J )

5 Hz, H₂), 5.74 (1H, d, J ) 5 Hz, H₃), 6.38 (1H, d, J ) 16 Hz,

H(CdC)), 6.12 (1H, d, J ) 16 Hz, H(CdC)), 7.21-7.38 (5H, m,

Ar H). ¹³C NMR (CDCl₃): 26.0 (C₆), 35.4 (C₅), 53.4 (OMe), 64.9

(C₁), 67.6 (C₃), 97.5 (C₂), 125.3 (Ar CH), 126.2 (Ar CH or CH-

(CdC)), 126.5 (Ar CH or CH(CdC)), 127.6 (Ar CH), 129.3 (CH-

(CdC)), 135.9 (Ar C), 142.5 (C₄), 222.2 (CO(Mn)). Anal. Calcd:

C, 61.73; H, 4.32. Found: C, 61.87; H, 4.37.

1

(CHCl₃): 1958, 2027 (CO(Mn)), 1606 (CO). H NMR (CDCl₃):

1.96 (3H, s, Me), 2.33 (1H, d, J ) 13 Hz, H_6exo), 3.50 (1H, dd,

J ) 13 and 6 Hz, H_6endo), 3.32 (1H, d, J ) 6 Hz, H₅), 6.01 (2H,

m, H₂, H₃), 7.41 (3H, m, Ar H). ¹³C NMR (CDCl₃): 22.2 (Me),

27.2 (C₆), 53.4 (C₅), 55.8 (C₁), 84.1 (C₃), 101.3 (C₂), 121.8 (C₄),

126.5 (Ar CH), 129.0 (Ar CH), 132.0 (Ar CH), 134.1 (Ar C),

189.4 (CO), 225.5 (CO(Mn)). Anal. Calcd: C, 52.63; H, 3.21.

Found: C, 52.41; H, 3.00.

16c (90%). IR (CHCl₃): 1957, 2027 (CO(Mn)), 1606 (CO).

¹H NMR (CDCl₃): 2.38 (1H, d, J ) 13 Hz, H_6exo), 3.19 (1H, dd,

J ) 13 and 5 Hz, H_6endo), 3.43 (1H, d, J ) 5 Hz, H₅), 3.48 (3H,

s, OMe), 6.05 (1H, d, J ) 6 Hz, H₂), 6.13 (1H, d, J ) 6 Hz, H₃),

7.06 (1H, dd, J ) 4 and 5 Hz, Ar H), 7.48 (1H, dd, J ) 4 and

1 Hz, Ar H), 7.55 (1H, dd, J ) 5 and 1 Hz, Ar H). ¹³C NMR

(CDCl₃): 26.9 (C₆), 31.1 (C₅), 38.1 (C₁), 54.8 (OMe), 72.6 (C₃),

100.4 (C₂), 127.6 (Ar CH), 131.0 (Ar CH), 132.2 (Ar CH), 142.6

(Ar C), 144.5 (C₄), 188.9 (CO), 225.5 (CO(Mn)). Anal. Calcd:

C, 50.29; H, 3.26. Found: C, 50.54; H, 3.51.

16f (73%). IR (CHCl₃): 1963, 2026 (CO(Mn)), 1610 (CO). ¹H

NMR (CDCl₃): 3.52 (3H, s, OMe), 3.80 (1H, dd, J ) 2.5 and

6.5 Hz, H₅), 4.80 (1H, d, J ) 6.5 Hz, H_6endo), 5.88 (1H, d, J )

6.5 Hz, H₂), 6.05 (1H, dd, J ) 2.5 and 6.5 Hz, H₃), 6.92 (2H, d,

J ) 7.5 Hz, Ar H), 7.01 (1H, dd, J ) 5 and 4 Hz, Ar H), 7.15

(3H, m, Ar H), 7.43 (1H, dd, J ) 4 and 1 Hz, Ar H), 7.48 (1H,

dd, J ) 5 and 1 Hz, Ar H). ¹³C NMR (CDCl₃): 40.6 (C₅), 45.1

(C₆), 55.0 (OMe), 61.2 (C₁), 72.4 (C₃), 97.9 (C₂), 125.6 (Ar CH),

127.0 (Ar CH), 127.6 (Ar CH), 128.7 (Ar CH), 130.7 (Ar CH),

132.1 (Ar CH), 142.1 (Ar C), 144.0 (Ar C), 146.2 (C₄), 188.4

(CO), 220.0 (CO(Mn)). Anal. Calcd: C, 58.08; H, 3.48. Found:

C, 57.92; H, 3.22.

17b (56%). IR (CHCl₃): 1962, 2030 (CO(Mn)), 1656 (CO).

¹H NMR (CDCl₃): 0.90 (3H, t, J ) 7 Hz, Me), 1.36 (4H, m,

CH₂), 1.61 (2H, t, J ) 7 Hz, CH₂), 1.92 (3H, s, Me), 2.35 (1H,

d, J ) 13 Hz, H_6exo), 3.14 (1H, dd, J ) 6 and 13 Hz, H_6endo),

3.28 (1H, d, J ) 6 Hz, H₅), 5.70 (1H, d, J ) 6 Hz, H₂), 5.92

(1H, d, J ) 6 Hz, H₃). ¹³C NMR (CDCl₃): 13.8 (Me), 22.1 (CH₂),

22.4 (CH₂), 26.2 (Me), 27.4 (CH₂), 27.8 (C₆), 53.1 (C₁), 56.6 (C₅),

83.4 (C₃), 98.6 (C₂), 128.4 (C₄), 203.5 (CO), 221.5 (CO(Mn)).

M/ z: 316.11.

13Z-E (global yield 29%). IR (CHCl₃): 1938, 2020 (CO(Mn)),

2210 (CdC). ¹H NMR (CDCl₃): 2.10 (1H, d, J ) 13 Hz, H_6exo(Z)),

2.18 (1H, d, J ) 13 Hz, H_6exo(E)), 2.66 (1H, dd, J ) 6 and 13

Hz, H_6endo(E)), 2.73 (1H, dd, J ) 6 and 13 Hz, H_6endo(Z)), 2.93

(1H, d, J ) 6 Hz, H_1(E)), 3.25 (2H, m, H_5(Z), H_5(E)), 3.28 (1H, d,

J ) 5.5 Hz, H_1(Z)), 4.75 (1H, t, J ) 6 Hz, H_4(E)), 4.91 (1H, t, J

) 6 Hz, H_4(Z)), 5.47 (1H, t, J ) 6 Hz, H_3(E)), 6.10 (1H, d, J ) 6

Hz, H_3(Z)), 6.44 (1H, d, J ) 16 Hz, H(CdC)_(E)), 6.84 (1H, d, J )

16 Hz, H(CdC)_(E)), 7.92 (1H, d, J ) 5 Hz, H(CdC)_(Z)), 7.29-

7.34 (11H, m, Ar H and H(CdC)_(Z)). ¹³C NMR (CDCl₃): 25.3

and 25.9 (C_6(Z)and (C_6(E)), 46.0 and 51.2 (C_5(Z)and C_5(E)), 51.3

and 51.7 (C_1(Z)and C_1(E)), 79.2 and 83.4 (C_3(Z)and C_3(E)), 96.9

and 97.8 (C_2(Z)and C_2(E)), 111.6 and 112.3 (C_4(Z)and C_4(E)), 127.0

and 127.5 (C(CdC)_(Z)and C(CdC)_(E)), 128.6 and 128.8 (Ar H_(Z)

and Ar H_(E)), 128.9 and 129.0 (Ar H_(Z)and Ar H_(E)), 129.1 and

129.3 (Ar H_(Z)and Ar H_(E)), 131.1 (C(CdC)_(Z)or C(CdC)_(E)),

133.8 and 133.9 (Ar H_(Z)and Ar H_(E)), 134.6 (C(CdC)_(Z)or C(Cd

C)_(E)), 223.0 and 223.1 (CO(Mn)_(Z)and CO(Mn)_(E)). Anal.

Calcd: C, 63.76; H, 4.09. Found: C, 63.52; H, 3.84.

Typ ica l Heck Rea ction P r oced u r e: Syn th esis of Com -

p lex 14. Pd₂dba₃(0.037 g, 0.04 mmol), AsPh₃(0.043 g, 0.14

mmol), and potassium carbonate (0.166 g, 1.20 mmol) were

added successively to complex 2c (0.114 g, 0.40 mmol) in 5

mL of anhydrous degassed DMF. After 10 min at room

temperature, phenylacrylate (0.066 mL, 0.40 mmol) was

introduced. The mixture was stirring 1.5 h, cold ice water (15

mL) was then added, and the reaction mixture was extracted

twice with diethyl ether (20 mL). The combined organic phases

were washed with a saturated ammonium chloride solution

(20 mL), dried over magnesium sulfate, filtered, and evapo-

rated under nitrogen flush. The residue was then purified by

flash chromatography on silica gel (petroleum ether/Et₂O, 80:

20) to deliver complex 14 in 18% yield. IR (CHCl₃): 1948, 2020

(CO(Mn)), 1718 (CO), 1627 (CdC). ¹H NMR (CDCl₃): 2.26 (1H,

d, J ) 13 Hz, H_6exo), 3.00 (1H, dd, J ) 6 and 13 Hz, H_6endo),

3.19 (1H, dd, J ) 6 and 2.5 Hz, H₅), 3.51 (3H, s, OMe), 5.18

(1H, d, J ) 6 Hz, H₂), 5.85 (1H, dd, J ) 2.5 and 6 Hz, H₃), 5.90

17c (45%). IR (CHCl₃): 1961, 2030 (CO(Mn)), 1656 (CO).

¹H NMR (CDCl₃): 0.89 (3H, t, J ) 7 Hz, CH₃), 1.25 (2H, q, J

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1911

) 7 Hz, CH₂), 1.32 (2H, q, J ) 7 Hz, CH₂), 1.55 (2H, t, J ) 7

Hz, CH₂), 1.96 (1H, d, J ) 13 Hz, H_6exo), 2.28 (1H, dd, J ) 7

and 13 Hz, H_6endo), 3.29 (1H, d, J ) 7 Hz, H₅), 3.46 (3H, s,

OMe), 5.79 (1H, d, J ) 6 Hz, H₂), 5.95 (1H, d, J ) 6 Hz, H₃).

¹³C NMR (CDCl₃): 14.0 (Me), 22.4 (CH₂), 25.1 (CH₂), 26.4 (C₆),

26.5 (CH₂), 35.9 (C₅), 38.6 (C₁), 54.8 (OMe), 72.2 (C₃), 97.7 (C₂),

144.7 (C₄), 203.0 (CO), 220.4 (CO(Mn)). Anal. Calcd: C, 54.27;

H, 5.16. Found: C, 54.54; H, 5.53.

Syn th esis of Yn e/en e-on e: P r ep a r a tion of 24. Pd₂dba₃

(0.027 g, 0.029 mmol) and AsPh₃(0.031 g, 0.10 mmol) were

added successively to complex 2c (0.082 g, 0.29 mmol) in 8

mL of anhydrous triethylamine. Carbon monoxide was pulled

through the reaction mixture, and trimethylsilylacetylene

(0.045 mL, 0.32 mmol) was introduced. The solution was

stirred for 7 h at 40 °C, cold ice water (15 mL) was then added,

and the reaction mixture was extracted twice with diethyl

ether (20 mL). The combined organic phases were washed with

a saturated ammonium chloride solution (20 mL), dried over

magnesium sulfate, filtered, and evaporated under nitrogen

flush. The residue was then purified by flash chromatography

on silica gel (petroleum ether/Et₂O, 90:10) to deliver complex

24 in 74% yield. IR (CHCl₃): 1960, 2030 (CO(Mn)), 2153 (Ct

1

18 (69%). IR (CHCl₃): 1960, 2023 (CO(Mn)), 1614 (CO). H

NMR (CDCl₃): 2.10 (3H, s, Me), 3.53 (3H, s, OMe), 3.72 (1H,

dd, J ) 2 and 5 Hz, H₅), 4.50 (1H, d, J ) 6.5 Hz, H_6endo), 5.86

(2H, m, H_3.H₂), 6.92 (1H, d, J ) 6.5 Hz, Ar H), 7.17 (3H, m,

Ar H). ¹³C NMR (CDCl₃): 23.5 (Me), 38.5 (C₅), 44.1 (C₆), 53.9

(OMe), 61.5 (C₁), 70.8 (C₃), 95.4 (C₂), 124.7 (Ar CH), 125.9 (Ar

CH), 127.3 (Ar CH), 143.0 (Ar C), 144.8 (C₄), 198.8 (CO), 220.2

(CO(Mn)). Anal. Calcd: C, 59.02; H, 4.13. Found: C, 59.09;

H, 4.15.

1

C), 1721 (CO). H NMR (CDCl₃): 0.21 (9H, s, Me), 1.94 (1H,

d, J ) 12 Hz, H_6exo), 3.10 (1H, dd, J ) 6 and 12 Hz, H_6endo),

3.16 (1H, d, J ) 6 Hz, H₅), 3.47 (3H, s, OMe), 5.90 (1H, m,

H₂), 6.02 (1H, m, H₃). ¹³C NMR (CDCl₃): 2.35 (Me), 24.9 (C₆),

31.2 (C₅), 55.1 (OMe), 57.5 (C₁), 73.9 (C₃), 99.7 and 100.8 (C(Ct

C)), 101.0 (C₂), 145.7 (C₄), 180.6 (CO), 227.8 (CO(Mn)). Anal.

Calcd: C, 51.61; H, 4.60. Found: C, 51.93; H, 4.46.

16d (26%). IR (CHCl₃): 1961, 2027 (CO(Mn)), 1609 (CO).

¹H NMR (CDCl₃): 2.08 (3H, s, Me), 2.38 (1H, d, J ) 12.5 Hz,

H

_6exo), 2.73 (1H, td, J ) 5 and 2 Hz, H₅), 3.19 (1H, dd, J ) 5

and 12.5 Hz, H_6endo), 4.75 (1H, t, J ) 5 Hz, H₄), 6.05 (1H, dd,

J ) 5 and 2 Hz, H₃), 7.34 (1H, t, J ) 4 Hz, Ar H), 7.45 (1H, d,

J ) 4 Hz, Ar H), 7.58 (1H, d, J ) 4 Hz, Ar H). ¹³C NMR

(CDCl₃): 21.7 (Me), 28.6 (C₆), 50.5 (C₅), 68.3 (C₁), 78.9 (C₂),

82.4 (C₃), 100.8 (C₄), 126.8 (Ar CH), 130.4 (Ar CH), 132.3 (Ar

CH), 133.7 (Ar C), 188.7 (CO), 225.8 (CO(Mn)). Anal. Calcd:

C, 52.63; H, 3.21. Found: C, 52.41; H, 3.08.

Performing the same reaction by substituting tributylstyryl-

stannane with trimethylsilylacetylene and DMF with Et₃N led

to complexes 25Z (27%) and 25E (28%). 25Z. IR (CHCl₃): 1948,

2024 (CO(Mn)), 1716 (CO), 1624 (CdC). ¹H NMR (CDCl₃): 2.07

(1H, d, J ) 13 Hz, H_6exo), 3.24 (1H, dd, J ) 6 and 2 Hz, H₅),

3.34 (1H, dd, J ) 6 and 13 Hz, H_6endo), 3.49 (3H, s, OMe), 5.93

(1H, d, J ) 6.5 Hz, H₂), 6.05 (1H, dd, J ) 6.5 and 2 Hz, H₃),

6.83 (1H, d, J ) 16 Hz, H(CdC)), 7.35 (3H, m, Ar H), 7.52

(2H, t, J ) 5 Hz, Ar H), 7.66 (1H, d, J ) 16 Hz, H(CdC)). ¹³C

NMR (CDCl₃): 27.0 (C₆), 38.8 (C₅), 54.6 (OMe), 55.7 (C₁), 72.7

(C₃), 98.0 (C₂), 118.7 (CH(CdC)), 128.3 (Ar CH), 129.0 (Ar CH),

130.3 (Ar CH), 135.0 (Ar CH), 143.0 (CH(CdC)), 144.7 (C₄),

191.8 (CO), 225.6 (CO(Mn)). Anal. Calcd: C, 60.33; H, 4.00.

Found: C, 60.18; H, 3.95. 25E (28%). IR (CHCl₃): 1952, 2026

(CO(Mn)), 1718 (CO), 1622 (CdC). ¹H NMR (CDCl₃): 1.88 (1H,

d, J ) 12 Hz, H_6exo), 3.22 (2H, m, H₅, H_6endo), 3.43 (3H, s, OMe),

5.40 (1H, d, J ) 5 Hz, H₂), 5.67 (1H, d, J ) 8 Hz, H(CdC)),

5.77 (1H, d, J ) 8 Hz, H(CdC)), 5.88 (1H, d, J ) 5 Hz, H₃),

7.31 (5H, m, Ar H). ¹³C NMR (CDCl₃): 25.0 (C₆), 38.4 (C₅),

54.2 (C₁), 54.7 (OMe), 72.4 (C₃), 99.6 (C₂), 116.7 (CH(CdC)),

125.9 (Ar CH), 128.6 (Ar CH), 129.0 (Ar CH), 135.8 (Ar C),

144.7 (C₄), 147.7 (CH(CdC)), 200.4 (CO), 221.8 (CO(Mn)). Anal.

Calcd: C, 60.33; H, 4.00. Found: C, 60.27; H, 3.92.

1

19 (70%). IR (CHCl₃): 1959, 2024 (CO(Mn)), 1602 (CO). H

NMR (CDCl₃): 2.06 (1H, d, J ) 13 Hz, H_6exo), 2.63 (1H, dd, J

) 6 and 13 Hz, H_6endo), 2.85 (1H, d, J ) 6 Hz, H₁), 2.91 (1H, t,

J ) 6 Hz, H₅), 4.82 (1H, d, J ) 6 Hz, H₄), 5.90 (1H, d, J ) 6

Hz, H₃), 7.34 (1H, m, Ar H), 7.55 (1H, m, Ar H), 7.73 (1H, m,

Ar H). ¹³C NMR (CDCl₃): 23.2 (C₆), 29.9 (Me), 49.9 (C₅), 50.4

(C₁), 78.8 (C₃), 97.0 (C₄), 115.3 (C₂), 127.4 (Ar CH), 127.6 (Ar

CH), 132.7 (Ar CH), 138.6 (Ar C), 166.7 (CO), 222.2 (CO(Mn)).

Anal. Calcd: C, 51.23; H, 2.76. Found: C, 51.31; H, 2.72.

Following the same procedure by using phenol, methanol,

morpholine, or p-(tolyl)SH as nucleophile allows the prepara-

tion of complexes 20, 21, 22, and 23, respectively.

1

20 (71%). IR (CHCl₃): 1958, 2029 (CO(Mn)), 1716 (CO). H

NMR (CDCl₃): 2.12 (1H, d, J ) 12 Hz, H_6exo), 3.25 (1H, dd, J

) 4 and 12 Hz, H_6endo), 3.29 (1H, d, J ) 4 Hz, H₅), 3.46 (3H, s,

OMe), 6.04 (1H, d, J ) 6 Hz, H₂), 6.12 (1H, d, J ) 6 Hz, H₃),

7.07 (2H, d, J ) 8 Hz, Ar H), 7.22 (1H, t, J ) 8 Hz, Ar H), 7.38

(2H, t, J ) 8 Hz, Ar H). ¹³C NMR (CDCl₃): 24.6 (C₆), 37.7 (C₅),

42.9 (C₁), 53.7 (OMe), 72.0 (C₃), 97.9 (C₂), 120.5 (Ar CH), 124.6

(Ar CH), 128.4 (Ar CH), 143.3 (Ar C), 149.8 (C₄), 168.2 (CO),

222.7 (CO(Mn)). Anal. Calcd: C, 55.45; H, 3.56. Found: C,

55.15; H, 3.61.

P d -Ca ta lyzed Nu cleop h ilic Su bstitu tion . Pd₂dba₃(0.020

g, 0.018 mmol), AsPh₃

(0.021 g, 0.070 mmol), potassium

cyanide (0.052 g, 0.80 mmol), and crown ether 18c6 (0.068 g,

0.26 mmol) were added to a solution of complex 2c (0.057 g,

0.20 mmol) in degassed DMF (5 mL). After stirring 7 h at

reflux, water was added (20 mL) and the reaction mixture was

extracted twice with ethyl acetate (20 mL). The combined

organic phases were washed with water (4 × 20 mL), dried

over magnesium sulfate, filtered, and evaporated under ni-

trogen flush. Complex 26 could not be purified. ¹H NMR

(CDCl₃): 2.80-2.97 (3H, m, H_6exo, H_6endo, H₅), 3.53 (3H, s, OMe),

5.07 (1H, d, J ) 5.5 Hz, H₂), 6.06 (1H, d, J ) 5.5 Hz, H₃). ¹³C

NMR (CDCl₃): 29.8 (C₆), 35.0 (C₅), 56.0 (OMe), 75.9 (C₃), 95.0

(C₁), 118.5 (C₂), 121.5 (CN), 149.5 (C₄), 222.7 (CO(Mn)).

Typ ica l Su bstitu tion P r oced u r e: P r ep a r a tion of 27a .

Pd₂dba₃(0.019 g, 0.021 mmol), AsPh₃(0.022 g, 0.07 mmol),

and cesium carbonate (0.082 g, 0.25 mmol) were added

successively to complex 2a (0.053 g, 0.21 mmol) in 8 mL of

anhydrous THF. After stirring 10 min, morpholine (0.020 mL,

0.20 mmol) was introduced. After refluxing for 5.5 h, cold ice

water (15 mL) was added and the reaction mixture was

extracted twice with diethyl ether (20 mL). The combined

organic phases were washed with a saturated ammonium

chloride solution (20 mL), dried over magnesium sulfate,

filtered, and evaporated under nitrogen flush. The residue was

then purified by flash chromatography on silica gel (petroleum

ether/Et₂O, 70:30) to deliver complex 27a in 84% yield. IR

21. ¹H NMR (CDCl₃): 2.05 (1H, d, J ) 12 Hz, H_6exo), 3.15

(2H, m, H_6endo, H₅), 3.40 (3H, s, OMe), 3.67 (3H, s, (CO)OMe),

5.90 (2H, m, H₂, H₃). ¹³C NMR (CDCl₃): 25.8 (C₆), 38.8 (C₅),

45.3 (C₁), 52.0 (CO₂Me), 54.0 (OMe), 72.3 (C₃), 98.6 (C₂), 143.3

(C₄), 188.9 (CO), 222.6 (CO(Mn)).

1

22 (48%). IR (CHCl₃): 1942, 2026 (CO(Mn)), 1612 (CO). H

NMR (CDCl₃): 2.33 (1H, d, J ) 11.5 Hz, H_6exo), 2.98 (1H, dd,

J ) 1.5 and 6 Hz, H₅), 3.35 (1H, dd, J ) 11.5 and 6 Hz, H_6endo),

3.44 (7H, m, OMe, NCH₂), 3.60 (4H, t, J ) 4.5 Hz, OCH₂), 5.42

(1H, d, J ) 6 Hz, H₂), 5.78 (1H, dd, J ) 6 and 1.5 Hz, H₃). ¹³C

NMR (CDCl₃): 29.8 (C₆), 34.9 (C₅), 45.6 (NCH₂), 54.6 (OMe),

58.7 (C₁), 66.9 (OCH₂), 68.0 (C₃), 98.6 (C₂), 143.7 (C₄), 170.7

(CO), 222.9 (CO(Mn)). Anal. Calcd: C, 49.87; H, 4.46; N, 3.87.

Found: C, 49.69; H, 4.47; N, 3.70.

1

23 (22%). IR (CHCl₃): 1941, 2033 (CO(Mn)), 1719 (CO). H

NMR (CDCl₃): 2.17 (1H, d, J ) 11 Hz, H_6exo), 2.35 (3H, s, Me),

3.23 (2H, m, H_5.H_6endo), 3.47 (3H, s, OMe), 5.99 (2H, m, H_3.

H₂), 7.19 (2H, d, J ) 8 Hz, Ar H), 7.28 (2H, d, J ) 8 Hz, Ar H).

¹³C NMR (CDCl₃): 21.4 (Me), 30.1 (C₆), 38.9 (C₅), 53.5 (OMe),

65.6 (C₁), 72.2 (C₃), 97.1 (C₂), 123.8 (C₈), 130.0 (Ar CH), 135.0

(Ar CH), 139.6 (Ar CH), 144.5 (C₄), 192.4 (CO), 224.8 (CO-

(Mn)). Anal. Calcd: C, 54.28; H, 3.80. Found: C, 53.90; H, 4.01.

1912 Organometallics, Vol. 22, No. 9, 2003

Auffrant et al.

(CHCl₃): 1950, 1995 (CO(Mn)). ¹H NMR (CDCl₃): 2.47 (1H,

d, J ) 14 Hz, H_6exo), 2.78 (1H, td, J ) 6 and 1.5 Hz, H₅), 2.95

(4H, t, J ) 5 Hz, NCH₂), 3.25 (1H, dd, J ) 6 and 14 Hz, H_6endo),

3.49 (1H, d, J ) 6 Hz, H₂), 3.70 (4H, t, J ) 5 Hz, OCH₂), 4.97

(1H, t, J ) 6 Hz, H₄), 5.54 (1H, dd, J ) 6 and 1.5 Hz, H₃). ¹³C

NMR (CDCl₃): 27.0 (C₆), 42.8 (C₅), 47.0 (NCH₂), 65.9 (OCH₂),

68.9 (C₁), 73.8 (C₃), 91.0 (C₂), 120.9 (C₄), 225.6 (CO(Mn)). Anal.

Calcd: C, 54.50; H, 4.65; N, 4.62. Found: C, 54.32; H, 4.79;

N, 4.43.

27b (76%). IR (CHCl₃): 1910, 1995 (CO(Mn)). ¹H NMR

(CDCl₃): 1.91 (3H, s, Me), 2.51 (1H, d, J ) 14 Hz, H_6exo), 2.77

(1H, dd, J ) 5.5 and 2 Hz, H₅), 2.90 (4H, t, J ) 6 Hz, NCH₂),

3.19 (1H, dd, J ) 14 and 5.5 Hz, H_6endo), 3.48 (1H, d, J ) 6 Hz,

H₂), 3.70 (4H, t, J ) 6 Hz, OCH₂), 5.40 (1H, dd, J ) 6 and 2

Hz, H₃). ¹³C NMR (CDCl₃): 22.1 (Me), 28.3 (C₆), 43.3 (C₅), 47.2

(NCH₂), 66.0 (OCH₂), 67.7 (C₁), 73.8 (C₃), 106.6 (C₂), 119.2 (C₄),

225.6 (CO(Mn)). Anal. Calcd: C, 53.01; H, 5.08; N, 4.42.

Found: C, 53.34; H, 5.20; N, 4.11.

27c (90%). IR (CHCl₃): 1910, 1996 (CO(Mn)). ¹H NMR

(CDCl₃): 2.58 (1H, d, J ) 14 Hz, H_6exo), 2.86 (4H, t, J ) 5.5

Hz, NCH₂), 2.93 (1H, dd, J ) 6 and 2.5 Hz, H₅), 3.25 (1H, ddd,

J ) 6, 14 and 2.5 Hz, H_6endo), 3.47 (1H, dd, J ) 6 and 2.5 Hz,

H₂), 3.57 (3H, s, OMe), 3.69 (4H, t, J ) 5.5 Hz, OCH₂), 5.33

(1H, dd, J ) 6 and 2.5 Hz, H₃). ¹³C NMR (CDCl₃): 29.2 (C₆),

35.2 (C₅), 47.6 (NCH₂), 54.3 (OMe), 58.1 (C₃), 64.5 (C₁), 66.0

(OCH₂), 118.4 (C₂), 140.6 (C₄), 225.0 (CO(Mn)). Anal. Calcd:

C, 50.46; H, 4.84; N, 4.20. Found: C, 50.71; H, 4.95; N, 3.96.

27f (55%). IR (CHCl₃): 1910, 1994 (CO(Mn)). ¹H NMR

(CDCl₃): 2.88 (4H, t, J ) 4.5 Hz, NCH₂), 3.43 (1H, dd, J ) 6

and 2.5 Hz, H₅), 3.60 (3H, s, OMe), 3.64 (4H, t, J ) 4.5 Hz,

OCH₂), 3.83 (1H, d, J ) 6 Hz, H₂), 4.46 (1H, d, J ) 6 Hz, H_6endo),

5.28 (1H, dd, J ) 6 and 2.5 Hz, H₃), 6.97 (2H, t, J ) 6.5 Hz,

Ar H), 7.16 (3H, m, Ar H). ¹³C NMR (CDCl₃): 43.0 (C₆), 44.1

(C₅), 47.6 (NCH₂), 54.3 (OMe), 58.3 (C₁), 65.2 (C₃), 65.9 (OCH₂),

120.1 (C₂), 125.8 (Ar CH), 127.0 (Ar CH), 128.8 (Ar CH), 139.3

(Ar C), 144.9 (C₄), 225.6 (CO(Mn)). Anal. Calcd: C, 58.69; H,

4.92; N, 3.42. Found: C, 58.88; H, 4.87; N, 3.22.

28 (84%). IR (CHCl₃): 1911, 1995 (CO(Mn)). ¹H NMR

(CDCl₃): 1.26 (3H, t, J ) 7.5 Hz, CH₃), 2.66 (1H, d, J ) 5.5

Hz, H₂), 2.75 (1H, d, J ) 15.5 Hz, H_6exo), 2.90 (1H, dd, J ) 5.5

and 2.5 Hz, H₅), 3.09 (5H, m, CH₂and H_6endo), 3.60 (3H, s,

OMe), 5.22 (1H, dd, J ) 5.5 and 2.5 Hz, H₃). ¹³C NMR

(CDCl₃): 12.4 (CH₃), 30.45 (C₆), 35.4 (C₅), 44.5 (CH₂), 51.7 (C₁),

54.0 (OMe), 58.5 (C₃), 92.5 (C₂), 143.4 (C₄), 224.4 (CO(Mn)).

Anal. Calcd: C, 52.67; H, 5.68; N, 4.17. Found: C, 52.45; H,

5.52; N, 4.39.

H₃). ¹³C NMR (CDCl₃): 19.6 (CH₃), 25.8 (CH), 27.9 (C₆), 38.7

(C₅), 54.7 (OMe), 71.0 (CH₂), 72.0 and 72.1 (C₁and C₃), 98.5

(C₂), 143.4 (C₄), 226.8 (CO(Mn)). Anal. Calcd: C, 52.51; H, 5.35.

Found: C, 52.23; H, 5.11.

The same procedure conducted with a thiol instead of an

alcohol allowed the isolation of complexes 32 and 33a ,c,f. 32

(73%). IR (CHCl₃): 1937, 2021 (CO(Mn)). ¹H NMR (CDCl₃):

1.23-1.41 (7H, m, CH₃, CH₂), 2.41 (1H, d, J ) 12 Hz, H_6exo),

2.56 (4H, m, CH₂), 2.86 (1H, dd, J ) 12 and 6 Hz, H_6endo), 3.02

(1H, dd, J ) 6 and 2.5 Hz, H₅), 3.46 (3H, s, OMe), 4.87 (1H, d,

J ) 6 Hz, H₂), 5.63 (1H, dd, J ) 6 and 2.5 Hz, H₃). ¹³C NMR

(CDCl₃): 17.6 (CH₃), 22.2 (CH₂), 28.5 (C₆), 29.7 (CH₂), 30.8

(CH₂), 32.3 (CH₂), 35.7 (C₅), 54.3 (OMe), 65.8 (C₃), 68.7 (C₁),

94.2 (C₂), 142.6 (C₄), 223.0 (CO(Mn)). Anal. Calcd: C, 51.42;

H, 5.47. Found: C, 51.58; H, 5.72.

33a (86%). IR (CHCl₃): 1937, 2020 (CO(Mn)). ¹H NMR

(CDCl₃): 2.33 (3H, s, CH₃), 2.39 (1H, d, J ) 13.5 Hz, H_6exo),

2.73 (1H, dd, J ) 13.5 and 6.5 Hz, H_6endo), 3.13 (1H, d, J ) 6.5

Hz, H₅), 4.83 (1H, dd, J ) 6.5 and 5.5 Hz, H₄), 4.93 (1H, d, J

) 5.5 Hz, H₂), 5.70 (1H, t, J ) 5.5 Hz, H₃), 7.12 (2H, d, J ) 8

Hz, Ar H), 7.21 (2H, d, J ) 8 Hz, Ar H). ¹³C NMR (CDCl₃):

21.2 (CH₃), 30.8 (C₆), 50.7 (C₅), 65.3 (C₁), 96.0 (C₃), 99.0 (C₂),

123.5 (C₄), 128.8 (Ar CH), 130.0 (Ar CH), 132.0 (Ar CH), 132.9

(Ar C), 226.4 (CO(Mn)). Anal. Calcd: C, 56.48; H, 3.85.

Found: C, 56.38; H, 4.28.

33c (93%). IR (CHCl₃): 1937, 2021 (CO(Mn)). ¹H NMR

(CDCl₃): 2.31 (3H, s, CH₃), 2.47 (1H, d, J ) 13 Hz, H_6exo), 2.77

(1H, dd, J ) 6 and 13 Hz, H_6endo), 3.02 (1H, d, J ) 6 Hz, H₅),

3.45 (3H, s, OMe), 4.96 (1H, d, J ) 5.5 Hz, H₂), 5.64 (1H, d, J

) 5.5 Hz, H₃), 7.01 (2H, d, J ) 8 Hz, Ar H), 7.21 (2H, d, J )

8 Hz, Ar H). ¹³C NMR (CDCl₃): 21.2 (CH₃), 33.0 (C₆), 36.3 (C₅),

54.5 (OMe), 65.0 (C₁), 66.9 (C₃), 96.2 (C₂), 128.8 (Ar CH), 130.0

(Ar CH), 131.7 (Ar CH), 133.8 (Ar CH), 137.8 (Ar C), 139.7

(Ar C), 142.7 (C₄), 221.3 (CO(Mn)). Anal. Calcd: C, 55.14; H,

4.08. Found: C, 55.12; H, 4.12.

33f (88%). IR (CHCl₃): 1937, 2022 (CO(Mn)). ¹H NMR

(CDCl₃): 2.31 (3H, s, CH₃), 3.44 (3H, s, OMe), 3.48 (1H, dd, J

) 6 and 3 Hz, H₅), 4.18 (1H, d, J ) 6 Hz, H_6endo), 4.78 (1H, d,

J ) 6 Hz, H₂), 5.55 (1H, dd, J ) 6 and 3 Hz, H₃), 6.97 (2H, d,

J ) 7.5 Hz, Ar H), 7.06 (2H, d, J ) 7.5 Hz, Ar H), 7.22 (5H, m,

Ar H). ¹³C NMR (CDCl₃): 21.3 (CH₃), 43.8 (C₅), 49.7 (C₆), 54.6

(OMe), 65.0 (C₁), 81.6 (C₃), 91.1 (C₂), 126.4 (Ar CH), 127.2 (Ar

CH), 128.4 (Ar CH), 130.0 (Ar CH), 132.5 (Ar C), 135.0 (Ar

CH), 139.3 (Ar C), 141.5 (Ar C), 145.2 (C₄), 222.0 (CO(Mn)).

Anal. Calcd: C, 61.88; H, 4.29. Found: C, 61.87; H, 4.19.

Using the same procedure with Et₃N as base and P-based

nucleophile gave access to complexes 34, 35, and 36. 34 (77%).

IR (CHCl₃): 1957, 2027 (CO(Mn)). ¹H NMR (CDCl₃): 1.28 (6H,

t, J ) 9 Hz, Me), 2.05 (1H, d, J ) 12 Hz, H_6exo), 3.04 (2H, m,

29 (42%). IR (CHCl₃): 1912, 1996 (CO(Mn)). ¹H NMR

(CDCl₃): 1.89 (3H, s, Me), 2.85 (1H, d, J ) 13 Hz, H_6exo), 2.91

(2H, m, H_6endo, H₅), 3.27 (1H, d, J ) 5.5 Hz, H₂), 3.78 (3H, s,

OMe), 4.73 (1H, s, NH), 5.34 (1H, d, J ) 5.5 Hz, H₃), 6.86 (2H,

d, J ) 8 Hz, Ar H), 7.04 (2H, d, J ) 8 Hz, Ar H). ¹³C NMR

(CDCl₃): 22.4 (Me), 29.8 (C₆), 32.9 (C₅), 55.5 (OMe), 64.0 (C₁),

74.0 (C₃), 105.4 (C₂), 114.7 (Ar CH), 116.6 (Ar CH), 120.7 (C₄),

131.0 (Ar C), 154.3 (Ar CH), 225.6 (CO(Mn)). Anal. Calcd: C,

55.30; H, 4.37; N, 3.79. Found: C, 54.95; H, 4.46; N, 3.48.

Substituting the amine by an alcohol and using NaH as a

base instead of cesium carbonate gave access to complexes 30

and 31. 30 (31%). IR (CHCl₃): 1958, 2028 (CO(Mn)). ¹H NMR

H

_6endo, H₅), 3.42 (3H, s, OMe), 4.12 (5H, m, CH_2.H₂), 5.95 (1H,

m, H₃). ¹³C NMR (CDCl₃): 16.7 (CH₃), 27.4 (C₆), 28.8 (CH₂),

37.6 (C₅), 54.6 (OMe), 62.7 (C₁), 71.9 (C₃), 100.4 (C₂), 144.1 (C₄),

217.7 (CO(Mn)). ³¹P NMR (CDCl₃): 28.2. Anal. Calcd: C, 43.7;

H, 4.73. Found: C, 43.94; H, 4.92.

For the preparation of 35 (43%) DMF was used instead of

THF. IR (CHCl₃): 1956, 2021 (CO(Mn)). ¹H NMR (CDCl₃):

2.06 (1H, d, J ) 11.5 Hz, H_6exo), 2.91 (2H, m, H_6endo, H₅), 3.42

(3H, s, OMe), 5.42 (1H, dd, J ) 5.5 and 10 Hz, H₂), 5.95 (1H,

d, J ) 5.5 Hz, H₃), 7.40 (4H, d, J ) 8 Hz, Ar H), 7.56 (4H, t,

J ) 8 Hz, Ar H), 7.72 (2H, t, J ) 8 Hz, Ar H). ¹³C NMR

(CDCl₃): 29.8 (C₆), 36.3 (C₅), 54.6 (OMe), 65.6 (C₁), 71.1 (C₃),

99.7 (C₂), 128.7 (Ar CH), 130.8 (Ar C), 132.0 (Ar CH), 132.1

(Ar CH), 144.3 (C₄), 217.1 (CO(Mn)). ³¹P NMR (CDCl₃): 32.7.

Anal. Calcd: C, 59.50; H, 4.05. Found: C, 59.6; H, 4.46.

36 (64%). IR (CHCl₃): 1942, 2018 (CO(Mn)). ¹H NMR

(CDCl₃): 2.26 (1H, d, J ) 13 Hz, H_6exo), 2.77 (1H, dd, J ) 13

and 6 Hz, H_6endo), 2.85 (1H, br d, J ) 6.0 Hz, H₅), 3.44 (3H, s,

OMe), 4.81 (1H, d, J ) 6 Hz, H₂), 5.80 (1H, dd, J ) 6 and 2.5

Hz, H₃), 7.19 (6H, m, Ar H), 7.43 (4H, d, J ) 7.5 Hz, Ar H).

¹³C NMR (CDCl₃): 29.7 (C₆), 35.2 (C₅), 54.4 (OMe), 59.0 (C₁),

68.9 (C₃), 99.1(C₂), 128.5 (Ar CH), 129.5 (Ar CH), 133.4 (Ar

(CDCl₃): 2.16 (1H, d, J ) 12 Hz, H_6exo), 3.25 (2H, m, H_6endo

,

H₅), 3.47 (3H, s, OMe), 3.85 (1H, m, H₂), 6.62 (1H, d, J ) 6

Hz, H₃), 7.00 (2H, t, J ) 7.5 Hz, Ar H), 7.20 (2H, d, J ) 7.5

Hz, Ar H), 7.36 (1H, t, J ) 7.5 Hz, Ar H). ¹³C NMR (CDCl₃):

25.7 (C₆), 38.8 (C₅), 54.8 (OMe), 65.9 (C₁), 73.0 (C₃), 99.0 (C₂),

116.0 (Ar CH), 125.7 (Ar CH), 129.4 (Ar CH), 144.4 (C₄), 150.9

(Ar C), 222.0 (CO(Mn)). Anal. Calcd: C, 56.50; H, 3.83.

Found: C, 56.18; H, 4.14.

31 (38%). IR (CHCl₃): 1958, 202 (CO(Mn)). ¹H NMR

(CDCl₃): 0.80-1.20 (7H, m, CH and CH₃), 1.75 (1H, d, J ) 13

Hz, H_6exo), 2.02 (1H, dd, J ) 13 and 5.5 Hz, H_6endo), 3.17 (1H,

dd, J ) 5.5 and 2 Hz, H₅), 3.31 (2H, m, CH₂), 3.44 (3H, s, OMe),

3.86 (1H, d, J ) 6.5 Hz, H₂), 5.90 (1H, dd, J ) 6.5 and 2 Hz,

+

Novel η⁶-(Arene)Mn(CO)₃Cations

Organometallics, Vol. 22, No. 9, 2003 1913

CH), 134.5 (Ar C), 143.7 (C₄), 219.3 (CO(Mn)). ³¹P NMR

(CDCl₃): 59.6. Anal. Calcd: C, 61.12; H, 4.20. Found: C, 61.28;

H, 4.20.

43 (85%). IR (CH₃CN): 2023, 2079 (CO(Mn)), 1705 (CO).

¹H NMR (acetone-d₆): 3.67 (8H, m, NCH₂and OCH₂), 4.18

(3H, s, OMe), 6.40 (1H, d, J ) 7.5 Hz, H₃and H₅), 7.45 (1H, d,

J ) 7.5 Hz, H₂and H₆). ¹³C NMR (acetone-d₆): 51.6 (NCH₂),

61.9 (OMe), 69.8 (OCH₂), 83.8 (C₃and C₅), 108.6 (C₂and C₆),

110.2 (C₁), 154.2 (C₄), 164.8 (CO), 218.7 (CO(Mn)). Anal. (+ 1

CH₂Cl₂): Calcd: C, 36.12; H, 3.22; N, 2.63. Found: C, 35.89;

H, 3.63; N, 2.88.

R ea r om a t iza t ion . Typ ica l R ea r om a t iza t ion P r oce-

d u r e: P r ep a r a tion of Com p lex 37. A solution of triphenyl

carbenium tetrafluoroborate (0.173 g, 0.65 mmol) in CH₂Cl₂

(3 mL) was added to a solution of complex 5c (0.086 g, 0.26

mmol) in CH₂Cl₂(3 mL). After stirring at room temperature

for 1.5 h, the solution was concentrated under N₂flush.

Addition of freshly distilled diethyl ether induced precipitation

of ether complex 37. The yellow solid was obtained by filtra-

tion. 37 (93%). IR (CH₃CN): 2025, 2080 (CO(Mn)). ¹H NMR

(acetone-d₆): 4.23 (3H, s, OCH₃), 6.63 (2H, d, J ) 8 Hz, H₃

and H₅), 7.30 (1H, t, J ) 4.5 Hz, Ar H), 7.58 (2H, d, J ) 8 Hz,

H₂and H₆), 7.86 (1H, d, J ) 4.5 Hz, Ar H), 7.97 (1H, d, J )

4.5 Hz, Ar H). ¹³C NMR (acetone d₆): 59.4 (OMe), 84.2 (C₃

and C₅), 100.7 (C₂and C₆), 103.2 (C₁), 128.7, 130.3, 131.8 (Ar

CH), 135.8 (Ar C), 149.1 (C₄), 216.8 (CO(Mn)). Anal. Calcd:

C, 40.42; H, 2.42. Found: C, 40.52; H, 2.59.

44 (65%). IR (CH₃CN): 2030, 2084 (CO(Mn)), 2157 (CtC),

1

1667 (CO). H NMR (acetone-d₆): 0.35 (9H, s, Me), 4.33 (3H,

s, OMe), 6.59 (1H, d, J ) 8 Hz, H₃and H₅), 7.78 (1H, d, J ) 8

Hz, H₂and H₆). ¹³C NMR (acetone-d₆): -2.0 (Me), 59.0 (OMe),

82.3 (C₃and C₅), 93.6 and 97.5 (C(CtC)), 105.2 (C₂and C₆),

114.2 (C₁), 153.4 (C₄), 171.6 (CO), 215.0 (CO(Mn)). Anal.

Calcd: C, 41.95; H, 3.49. Found: C, 42.16; H, 3.61.

45 (35%, two steps). IR (CH₃CN): 2011, 2046 (CO(Mn)),

2233 (CN). ¹H NMR (acetone-d₆): 3.72 (3H, s, OMe), 7.76 (2H,

d, J ) 7 Hz, H₃and H₅), 7.89 (2H, d, J ) 7 Hz, H₂and H₆). ¹³

C

NMR (acetone-d₆): 54.2 (OMe), 77.1 (C₃and C₅), 121.1 (CN),

131.0 (C₁), 144.0 (C₄), 147.8 (C₂and C₆), 216.9 (CO(Mn)).

X-r a y Cr ysta l Str u ctu r e Deter m in a tion for 23, 33f, 40c,

a n d 44. The selected crystals were mounted onto the top of a

glass rod. Accurate cell dimensions, orientation matrixes, and

data collections were performed at -7 °C for 40c and at room

temperature for the three other compounds, on a Enraf-Nonius

MACH-3 diffractometer equipped with graphite-monochro-

mated Mo KR radiation. No significant variations were ob-

served in the intensities of two checked reflections during data

collection for 23, 33f, and 44; however, strong decay was

observed for 40c (44%). This decay was corrected according to

standards. More complete crystallographic data, collection

parameters, and other significant details are listed in Table

12. Computations were performed by using the PC version of

Crystals.⁴⁵The usual corrections for Lorentz and polarization

effects were applied. Scattering factors and corrections for

anomalous dispersion were taken from International Tables

for X-ray Crystallography.⁴⁶The structures were solved by

direct methods (SHELXS⁴⁷) and refined by full-matrix least-

squares. Non-hydrogen atoms were refined anisotropically

The same procedure was applied to the synthesis of com-

plexes 38, 39E, 40b, 40c, 41, 42, 43, and 44.

38 (96%). IR (CH₃CN): 2024, 2079 (CO(Mn)), 2208 (CtC).

¹H NMR (acetone-d₆): 3.84 (3H, s, OMe), 7.00 (2H, d, J ) 7.5

Hz, H₃and H₅), 7.40 (5H, m, Ar H), 7.64 (2H, d, J ) 7.5 Hz,

H₂and H₆). ¹³C NMR (acetone-d₆): 60.0 (OMe), 85.0 (C₃and

C₅), 101.6 (C₂and C₆), 106.4 (C(CtC)), 121.0 (C₁), 128.6 (Ar

CH), 131.5 (Ar CH), 132.9 (Ar C), 133.5 (Ar CH), 138.6 (C(Ct

C)), 148.9 (C₄), 216.8 (CO(Mn)). Anal. (+1 CH₂Cl₂) Calcd: C,

47.15; H, 2.89. Found: C, 46.93; H, 2.76.

39E (94%). IR (CH₃CN): 1639 (CdC), 2017 (CO(Mn)). ¹H

NMR (acetone-d₆) 4.18 (3H, s, OMe), 6.92 (2H, d, J ) 7.5 Hz,

H₃and H₅), 7.12-7.64 (9H, m, H₂, H₆, Ar H and H(CdC)). ¹³

C

NMR (acetone-d₆): 60.1 (OMe), 85.0 (C₃and C₅), 101.6 (C₂and

C₆), 106.4 (CH(CdC)), 121.1 (C₁), 128.8 and 129.8 (Ar CH),

130.6 (Ar CH), 135.6 (Ar C), 138.4 (CH(CdC)), 148.9 (C₄), 216.8

(CO(Mn)). Anal. (+1 CH₂Cl₂) Calcd: C, 44.90; H, 3.36. Found:

C, 44.98; H, 3.37.

40b (95%). IR (CH₃CN): 2021, 2082 (CO(Mn)), 1720 (CO).

¹H NMR (acetone-d₆): 2.73 (3H, s, Me), 6.83 (1H, d, J ) 7 Hz,

H₃and H₅), 7.38 (1H, dd, J ) 4 and 5 Hz, Ar H), 7.52 (2H, d,

J ) 7 Hz, H₂and H₆), 8.07 (1H, d, J ) 4 Hz, Ar H), 8.25 (1H,

d, J ) 5 Hz, Ar H). ¹³C NMR (acetone-d₆): 20.4 (Me), 98.5 (C₃

and C₅), 103.9 (C₂and C₆), 110.7 (C₁), 124.2 (Ar C), 130.3 (Ar

CH), 138.9 (Ar CH), 139.4 (Ar CH), 141.8 (C₄), 181.9 (CO),

215.4 (CO(Mn)). Anal. Calcd: C, 42.06; H, 2.33. Found: C,

42.06; H, 2.35.

-

excluding the agitated BF₄anion and the solvent molecule

(acetone) located on the 2-fold axis in 40c. For these two

molecules it was necessary to apply restraints on the bond

lengths and angles. In all cases hydrogen atoms were intro-

duced in calculated positions in the last refinements and were

allocated an overall refinable isotropic thermal parameter.

40c (95%). IR (CH₃CN): 2023. 2081 (CO(Mn)), 1720 (CO).

¹H NMR (acetone-d₆): 4.27 (3H, s, OMe), 6.58 (1H, d, J ) 7.5

Hz, H₃and H₅), 7.36 (1H, d, J ) 4.5 Hz, Ar H), 7.66 (1H, d, J

) 7.5 Hz, H₂and H₆), 8.03 (1H, t, J ) 4.5 Hz, Ar H), 8.24 (1H,

d, J ) 4.5 Hz, Ar H). ¹³C NMR (acetone-d₆): 58.6 (OMe), 81.3

(C₃and C₅), 105.3 (C₂and C₆), 111.2 (C₁), 129.5 (Ar C), 138.0

(Ar CH), 138.5 (Ar CH), 141.1 (Ar CH), 151.7 (C₄), 181.0 (CO),

214.7 (CO(Mn)). Anal. Calcd: C, 40.42; H, 2.42. Found: C,

40.52; H, 2.59.

41 (70%). IR (CH₃CN): 2021, 2080 (CO(Mn)), 1725 (CO).

¹H NMR (acetone-d₆): 4.18 (3H, s, OMe), 6.49 (2H, d, J ) 2.5

Hz, H₃and H₅), 7.15 (1H, m, Ar H), 7.33 (2H, d, J ) 5.5 Hz,

Ar H), 7.37 (2H, d, J ) 5.5 Hz, Ar H), 7.69 (2H, d, J ) 2.5 Hz,

H₂and H₆). ¹³C NMR (acetone-d₆): 57.7 (OMe), 81.4 (C₃and

C₅), 104.5 (C₂and C₆), 111.9 (C₁), 120.7 (Ar CH), 125.7 (Ar

CH), 128.6 (Ar CH), 150.2 (Ar C), 159.8 (C₄), 163.0 (CO), 213.0

(CO(Mn)). Anal. Calcd: C, 44.87; H, 2.42. Found: C, 40.52;

H, 2.59.

Ack n ow led gm en t. We thank the CNRS and the

European Community TMR program, No. FMRX-CT98-

0166, and COST D14 program for financial suppport

and the Ministe`re de l’Education Nationale et de la

Recherche for a MENRT grant to A.A.

Su p p or tin g In for m a tion Ava ila ble: Text giving tables

of crystal data, atomic coordinates, and bond distances and

angles for complexes 23, 33f, 40c, and 44. This material is

available free of charge via the Internet at http://pubs.acs.org.

OM021017O

(44) Watkin, D. J .; Prout, C. K.; Carruthers, J . R.; Betteridge, P.

W. Crystals, issue 10; Chemical Crystallography Laboratory: Univer-

sity of Oxford, U.K., 1996.

(45) Cromer, D. T. International Tables for X-ray Crystallography,

Vol. IV; Kynoch Press: Birmingham, U.K., 1974.

42 (77% two steps). IR (CH₃CN): 2018, 2082 (CO(Mn)), 1718

1

(CO). H NMR (acetone-d₆): 4.08 (3H, s, CO₂Me), 4.28 (3H, s,

OMe), 6.56 (2H, d, J ) 7 Hz, H₃and H₅), 7.68 (2H, d, J ) 7

Hz, H₂and H₆). ¹³C NMR (acetone-d₆): 57.7 (OMe), 62.4 (CO₂-

Me), 81.9 (C₁), 86.2 (C₃and C₅), 109.3 (C₂and C₆), 154.2 (C₄),

166.3 (CO), 214.6 (CO(Mn)). Anal. Calcd: C, 36.77; H, 2.57.

Found: C, 36.34; H, 2.42.

(46) Altomare, A.; Cascarano, G.; Giacovazzo G.; Guagliardi A.;

Burla M. C.; Polidori, G.; Camalli, M. SIR92, a program for automatic

solution of crystal structures by direct methods. J . Appl. Crystallogr.

1994, 27, 435.

(47) Sheldrick, G. M. SHELXS86, program for the solution of crystal

structures; University of Gottingen: Fed. Rep. of Germany, 1986.

Article Doi

Palladium-catalyzed chloride substitution of η5-(Chlorocyclohexadienyl)Mn(CO)3 complexes: An access to novel η6-(Arene)Mn(CO)3+ cations

DOI: 10.1021/om021017o

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