Synthesis of polycyclic cyclohexadienyl ruthenium(II) Complexes from η6-arene precursors via phosphine-promoted intramolecular nucleophilic aromatic addition

Article abstract of DOI:10.1021/om900178w

An experimentally straightforward procedure for the synthesis of structurally elaborate cyclohexadienyl ruthenium(II) complexes has been developed along the lines of the Morita - Baylis - Hillman reaction. Coordination of (cyclopentadienyl)Ru(II) fragment

Full text of DOI:10.1021/om900178w

Organometallics 2009, 28, 3869–3875 3869
DOI: 10.1021/om900178w
Synthesis of Polycyclic Cyclohexadienyl Ruthenium(II) Complexes from
η6-Arene Precursors via Phosphine-Promoted Intramolecular
Nucleophilic Aromatic Addition
F. Christopher Pigge,* R. Dhanya, and Dale C. Swenson
Department of Chemistry, University of Iowa, Iowa City, Iowa 52242
Received March 6, 2009
An experimentally straightforward procedure for the synthesis of structurally elaborate cyclohex-
adienyl ruthenium(II) complexes has been developed along the lines of the Morita-Baylis-Hillman
reaction. Coordination of (cyclopentadienyl)Ru(II) fragments to N-benzyl and N-phenethyl acryla-
mides was found to facilitate conversion to stable cyclohexadienyl complexes via Bu3P-mediated
intramolecular cyclization. An ipso cyclization was observed in all but one case, resulting in
formation of five- or six-membered spirolactams at C6 positions of cyclohexadienyl ligands.
Acrylamides prepared from dihydroindene and tetrahydronaphthalene precursors were suitable
substrates for this transformation, affording access to novel tricyclic cyclohexadienyl complexes. One
such complex was characterized by X-ray crystallography.
Introduction
facilitates nucleophilic aromatic addition to produce (η5-cyclo-
hexadienyl)metal derivatives. In contrast to their (η6-arene)
progenitors, however, the chemistry and synthetic utility of
cyclohexadienyl adducts have not been extensively investi-
gated.5,6
Arene metal complexes have proven to be versatile organo-
metallic intermediates that are widely used in organic synthesis
and materials chemistry.1,2 In particular, various arene com-
plexes of Cr(0), Mn(I), Fe(II), and Ru(II) are easily prepared
and possess excellent air and moisture stability.3 The utility of
these complexes is due in large part to the enhanced electro-
philicity exhibited by the coordinated arene ligand.4 Conse-
quently, arene functionalization can be accomplished via
normally unfavorable reaction manifolds such as nucleophilic
aromatic substitution. This enhanced arene reactivity also
For the past several years we have been developing Ru-
mediated dearomatization reaction sequences that lead to genera-
tion of 2-azaspiro[4.5]decanes starting from various (η6-N-benzy-
lamide) complexes.7,8 A particularly straightforward procedure
utilizing simple benzyl acrylamides is illustrated in Scheme 1.9
Conversion of 1 to 2 is envisioned to proceed via Michael-type
addition of a phosphine promoter to the acrylamide side chain.
Regioselective nucleophilic aromatic addition to the ipso position
followed by base-mediated elimination of phosphine affords
cyclohexadienyl complexes 2 as stable and isolable products.
The presence of an electron-releasing substituent at the cyclohex-
adienyl C3 position (R = OMe in Scheme 1) then allows oxidative
demetalation of 2 to proceed with preservation of the spirocyclic
linkage.
An interesting observation in the context of the chemistry
shown in Scheme 1 concerns the compatibility of N-phenethyl
acrylamide complexes with the spirocyclization manifold
(i.e., 1, n = 1).9 These substrates reacted smoothly in the
presence of Bu3P to deliver 6,6-spirofused products in good
yield, whereas closely related complexes possessing alternative
*Corresponding author. E-mail: chris-pigge@uiowa.edu.
ꢀ
::
(1) (a) Lavy, S.; Perez-Luna, A.; Kundig, E. P. Synlett 2008, 2621.
ꢀ
(b) Rosillo, M.; Domꢀınguez, G.; Perez-Castells, J. Chem. Soc. Rev. 2007,
36, 1589. (c) Pearson, A. J.; Paramahamsan, H.; Dudones, J. D. Org.
~
Lett. 2004, 6, 2121. (d) Bolm, C.; Muniz, K. Chem. Soc. Rev. 1999, 28, 51.
(2) (a) Astruc, D.; Ornelas, C.; Ruiz, J. Acc. Chem. Res. 2008, 41, 841.
(b) Park, K. H.; Jang, K.; Cho, Y.; Chun, J.; Kim, H. J.; Sweigart, D. A.;
Son, S. U. Adv. Mater. 2007, 19, 2547. (c) Rigby, J. H.; Kondratenko,
M. A. Org. Lett. 2001, 3, 3683.
(3) Kundig, E. P. Top. Organomet. Chem. 2004, 7, 3.
(4) Recent examples: (a) Pearson, A. J.; Ciurea, D. V.; Velankar, A.
Tetrahedron Lett. 2008, 49, 1922. (b) Storm, J. P.; Andersson, C.-M.
J. Org. Chem. 2000, 65, 5264. Reviews: (c) Semmelhack, M. F.;
Chlenov, A. Top. Organomet. Chem. 2004, 7, 43. (d) Abd-El-Aziz,
A. S.; Bernardin, S. Coord. Chem. Rev. 2000, 203, 219. (e) Pike, R. D.;
Sweigart, D. A. Coord. Chem. Rev. 1999, 187, 183.
::
(6) (η5-Cyclohexadienyl)Fe(CO)3 cations have been extensively used
in synthesis; however these materials are typically prepared from iron
diene precursors. For example, see: Owen, D. A.; Malkov, A. V.;
Palotai, I. M.; Roe, C.; Sandoe, E. J.; Stephenson, G. R. Chem.;Eur.
J. 2007, 13, 4293, and references therein.
(7) (a) Pigge, F. C.; Dalvi, R. Tetrahedron 2008, 64, 10123. (b) Pigge,
F. C.; Coniglio, J. J.; Dalvi, R. J. Am. Chem. Soc. 2006, 128, 3498.
(c) Pigge, F. C.; Coniglio, J. J.; Rath, N. P. J. Org. Chem. 2004, 69, 1161.
(d) Pigge, F. C.; Coniglio, J. J.; Fang, S. Organometallics 2002, 21, 4505.
(5) For examples, see: (a) Eloi, A.; Rose-Munch, F.; Rose, E.;
ꢀ
Chavarot-Kerlidou, M.; Gerard, H. Organometallics 2009, 28, 925,
and references therein. (b) Kirss, R. U.; Henriksen, A.; Forsyth, D. A.;
Feighery, W. Inorg. Chim. Acta 2006, 359, 4393. (c) Older, C. M.;
Stryker, J. M. J. Am. Chem. Soc. 2000, 122, 2784. (d) Bhambri, S.;
Bishop, A.; Kaltsoyannis, N.; Tocher, D. A. J. Chem. Soc., Dalton
Trans. 1998, 3379. (e) Shirin, Z.; Pramanik, A.; Ghosh, P.; Mukherjee,
R. Inorg. Chem. 1996, 35, 3431. (f) Djukic, J.-P.; Rose-Munch, F.; Rose,
E.; Dromzee, Y. J. Am. Chem. Soc. 1993, 115, 6434. (g) Sutherland, R.
(8) For a review of metal-mediated dearomatization, see: (a) Pape,
A. R.; Kaliappan, K. P.; Kundig, E. P. Chem. Rev. 2000, 100, 2917.
(b) Keane, J. M.; Harman, W. D. Organometallics 2005, 24, 1786.
(9) Pigge, F. C.; Dhanya, R.; Hoefgen, E. R. Angew. Chem., Int. Ed.
2007, 46, 2887.
ꢀ
G.; Chowdhury, R. L.; Piorko, A.; Lee, C. C. J. Organomet. Chem.
::
1987, 319, 379. (h) Vol’kenau, N. A.; Bolesova, L. N.; Shul’pina,
L. S.; Kitaigorodskii, A. N. J. Organomet. Chem. 1984, 267, 313.
(i) Robertson, D. R.; Robertson, I. W.; Stephenson, T. A. J. Organomet.
Chem. 1980, 202, 309.
r
2009 American Chemical Society
Published on Web 05/19/2009
pubs.acs.org/Organometallics

3870 Organometallics, Vol. 28, No. 13, 2009
Pigge et al.
Scheme 1
Table 1. Phosphine-Promoted Transformations of Phenethylamine-Based
Arene Complexes
Scheme 2
a Counterion is PF6 in all cases.
diastereomers. The exo complex has been assigned primarily
on the basis of subsequent reactivity (vide infra), as the
presence of amide bond rotamers resulted in a complicated
NMR spectrum that precluded definitive determination of
stereochemistry.
pronucleophilic side-chain functionality (acetoacetamide 4
and β-amidophosphonate 5) failed to undergo similar trans-
formations (Scheme 2). Notably, however, the N-benzyl
analogues 6 and 7 (with n = 0) have been efficiently converted
to spirolactam cyclohexadienyl complexes 8.7 On the basis of
these initial observations we became interested in testing the
limits of phosphine-promoted nucleophilic aromatic addition
as a means to construct unique and structurally elaborate
cyclohexadienyl ruthenium(II) complexes. We now report the
successful application of this method for the preparation of
several bicyclic (azaspiro[5.5]undecane) and tricyclic cyclo-
hexadienyl complexes. One example from this latter family of
compounds has been structurally characterized by X-ray
crystallography.
As indicated in Table 1, 9a, 9b, and 9d were all converted to
the corresponding spirocyclic cyclohexadienyl products 10a,
10b, and 10d in good yield upon treatment with Bu3P and
1
NaH in DME at room temperature. The H NMR spectra
clearly reveal transformation of the bound arenes into cyclo-
hexadienyl ligands. Diagnostic signals include a triplet at∼5.5
ppm (C3 hydrogen, see 10a for numbering), triplet(s) at ∼4.5
ppm (C2 and C4), and upfield doublet(s) at ∼2-3 ppm (C1
and C5). Additionally, the signal for the Cp hydrogens
experiences anupfield shift from∼5.5ppm inarene complexes
9 to ∼4.8 ppm in 10. The stereochemistry at the newly
generated C-C bond is envisioned to arise from exo addition
of the nucleophilic side chain to the coordinated arene, a result
consistent with the well-known reactivity profile of arene
metal complexes and our own observations in closely related
systems.4,7,8a Thus, the successful construction of sterically
congested and structurally intriguing tricyclic spirolactam 10d
seemingly confirms the stereochemical assignment of 9d.
Substrate 9c, featuring a benzylic quaternary center, exhibits
a different reactivity. Intramolecular nucleophilic aromatic
addition was found to give a cyclohexadienyl product exhibit-
ing a doublet at 5.67 ppm corresponding to a C3 cyclohex-
adienyl hydrogen and a doublet at 4.46 ppm (integrating to
one hydrogen) corresponding to a C2 cyclohexadienyl
hydrogen. Since the spirocyclic product would possess two
Results and Discussion
The first set of substrates examined in this study all featured
arene ligands with a two-carbon linker between the arene ring
and the acrylamide group. Introduction of the cyclopentadie-
nyl (Cp) ruthenium fragment was achieved in high yields (70-
98%)upon exposure of the areneligands to[(CH3CN)3RuCp]
[PF6] in warm dichloroethane.10 In this manner (η6-arene)
complexes 9a-9d were obtained (Table 1). It is notable that
selective metalation of a single phenyl ring in 9b occurred
in the presence of 1 equiv of the Ru-tris(acetonitrile) salt.
Complex 9d can potentially exist as a mixture of exo and endo
(10) (a) Gill, T. P.; Mann, K. R. Organometallics 1982, 1, 485.
(b) Kundig, E. P.; Monnier, F. R. Adv. Synth. Catal. 2004, 346, 901.
::

Article
Organometallics, Vol. 28, No. 13, 2009 3871
Table 2. Synthesis of Spirotricyclic Cyclohexadienyl Ru(II) Complexes
˚
Figure 1. Molecular structure of 12a. Selected bond distances (A):
Ru-C1, 2.178; Ru-C2, 2.164; Ru-C3, 2.171; Ru-C4, 2.180;
Ru-C5, 2.210; Ru-C15, 2.181; Ru-C16, 2.202; Ru-C17, 2.245;
Ru-C18, 2.231; Ru-C19, 2.178.
complicated arene ruthenium complexes may be amenable
to phosphine-promoted spirocyclization. To test the gen-
erality of the process, several acrylamide arene ruthenium
complexes were prepared from indanone and tetralone
precursors. Each of these materials was then subjected to
our standard intramolecular cyclization conditions (see
Table 1), and the results are tabulated in Table 2. As shown
in entry 1, a dihydroindene acrylamide complex (11a) was
smoothly converted to cyclohexadienyl product 12a in 59%
isolated yield. As with 9d, isolation of the exo diastereomer
of 11a upon coordination of the CpRu(II) fragment is
inferred from subsequent reactivity and an X-ray crystal
structure analysis of 12a (vide infra). The stereochemistry of
the other (η6-arene) complexes shown in Table 2 was
assigned by analogy to 11a. Complex 11b features a β,β-
disubstituted acrylamide unit. Nonetheless, cyclization was
found to proceed smoothly, and 12b was isolated in 54%
yield as a separable ∼1:1 mixture of R,β- and β,γ-unsatu-
rated spirolactams. The reaction was found to be compatible
with additional substitution on the dihydroindene frame-
work (11c) as well as the presence of an oxygen heteroatom
(11d). Tetrahydronaphthalene derivatives 11e-11g also
gave the reaction to afford the 6,6,5-fused tricycles 12e-
12g with isolated yields of ∼60% in each case.
a Counterion is PF6. b 1:1 mixture of alkene isomers. c ∼5:1 mixture of
C3 diastereomers. d ∼2:1 mixture of C3 diastereomers.
hydrogens at the C2/C4 positions and no C3 hydrogen, the
product of this reaction must result from cyclization to an
ortho position, affording fused bicyclic cyclohexadienyl com-
plex 10c. This regioselectivity may arise from an electronic
effect exerted by the methoxy substituent, as Semmelhack has
shown that methoxy groups in (arene)Cr(CO)3 complexes
direct nucleophilic aromatic addition to occur at meta posi-
tions.4c,11 However, a simpler analogue of 9c also possessing a
para methoxy group but lacking a benzylic substituent (1, see
Scheme 1) was found to exhibit regioselective ipso cyclization
under the same reaction conditions.9 Consequently, we attri-
bute the behavior of 9c primarily to steric effects emanating
from the benzylic cyclohexyl substituent.
Crystals of 12a suitable for X-ray diffraction were obtained
from slow evaporation of an EtOAc solution, and the mole-
cular structure is shown in Figure 1.12 The exo orientation of
the spirolactam ring with respect to the CpRu(II) fragment is
clearly evident. The CpRu(II) fragment is located on a
line between the centroids of the Cp ring and cyclohexadienyl
ligand (centroid-Ru-centroid angle ∼178°). The average
Ru-carbon bond lengths to the cyclohexadienyl and
˚
Cp ligands are 2.181 and 2.207 A, respectively, indicative of
(12) Crystal data: fw = 380.44, orthorhombic, P212121, a = 7.9074
The successful elaboration of 9d into tricyclic cyclohex-
adienyl 10d seemed to indicate that structurally more
3
˚
˚
˚
˚
(9) A, b = 8.1560(9) A, c = 24.107(3) A, V = 1554.7(3)A, Z = 4, Dcalc
=
1.625 g cm-3, μ = 1.010 mm-1, T (K) = 190(2), reflections = 37452,
unique reflections = 3572, reflections I > 2σ(I ) = 3348, parameters =
201, R1 [I > 2σ(I )] = 0.0247, wR2 = 0.0541. This structure has been
deposited with the Cambridge Crystallographic Database (CCDC
#722760).
(11) (a) Semmelhack, M. F.; Harrison, J. J.; Thebtaranonth, Y.
J. Org. Chem. 1979, 44, 3275. (b) Semmelhack, M. F.; Yamashita, A.
J. Am. Chem. Soc. 1980, 102, 5924.

3872 Organometallics, Vol. 28, No. 13, 2009
Pigge et al.
slightly stronger bonding to the cyclohexadienyl ligand.13
In the solid state both the Cp and cyclohexadienyl ligands
are slightly tilted such that the Ru-carbon bonds distal
from the fused ring substituent (Ru-C2, Ru-C3, Ru-C15,
and Ru-C19) are slightly shorter than the remaining
Ru-carbon linkages. Carbon-carbon distances within the
η5-cyclohexadienyl ligand are all comparable and range from
Scheme 3
˚
1.409 to 1.419 A.
From the results described above we conclude that phos-
phine-promoted intramolecular nucleophilic aromatic addition
of acrylamide-functionalized arene ruthenium complexes pro-
vides a relatively straightforward means of constructing sub-
stituted and stable cyclohexadienyl ruthenium complexes. The
basis for the enhanced reactivity exhibited by the acrylamide/
phosphine reagent combination compared to β-amido phos-
phonate anions derived from complexes such as 5 (n = 1) is
attributed to differences in reactivity of the anion intermediates.
While our previous success in manipulating N-benzyl β-amido
phosphonate complexes (see Scheme 2) demonstrates that
stabilized phosphoryl anions (13) are suitable partners for
nucleophilic aromatic additions,7a,7b the wider substrate scope
evident in phosphine-promoted reactions of acrylamide
complexes presumably reflects enhanced reactivity (greater
nucleophilicity) of zwitterion 14. Additionally, the zwitterionic
intermediate 14 may adopt a more ordered conformation
conducive to intramolecular nucleophilic addition as com-
pared to the nominally more flexible phosphonate anion 13.
Evidence supporting the importance of side-chain con-
formational effects in these types of reactions is provided
by the failure of 15 and 16 (complexes in which the amide
group has been replaced with an ester or alkyl linkage,
respectively) to afford cyclohexadienyl ruthenium derivatives
upon treatment with Bu3P/NaH.
migration of the vinyl group.7,9 No evidence for the addition
of H2O to a cyclohexadienyl terminal position was detected,
although this type of transformation has been observed in
closely related substrates. It should be noted that application
of a CO atmosphere resulted in recovery of the CpRu(II)
fragment. The 3-benzazepine product 17 was obtained in
excellent isolated yield, while the tetrahydroisoquinolinone
derivatives 18 and 19 were formed slightly less efficiently. The
NMR spectra of these latter two compounds are fully con-
sistent with the illustrated structures; however, rapid decom-
position prevented further characterization. Cyclohexadienyl
complex 12g was also subjected to oxidative demetalation
reaction conditions. In this case the spirocyclic linkage
was preserved in the metal-free product due to the presence
of the C3 methoxy substituent and 21 was isolated in good
yield (eq 1).
Conclusions
In summary, the conversion of easily prepared cationic
arene ruthenium complexes bearing acrylamide side chains
into neutral spirocyclic cyclohexadienyl derivatives has been
achieved in the presence of Bu3P and NaH. These mild
reaction conditions were found to be compatible with a range
of acrylamide substrates, and a variety of structurally intri-
guing (cyclohexadienyl)RuCp products have been success-
fully prepared and characterized. Superficially these
transformations resemble the well-known Morita-Baylis-
Hillman reaction.14 It is noteworthy that while the com-
pounds examined in this study are all racemic, enantiomeri-
cally pure analogues of ligands found in arene complexes 11
should be easily accessible.15 Coupled with the high stereo-
selectivity exhibited in the arene complexation and nucleo-
philic aromatic addition reactions described above, the use of
such optically enriched ligands would provide entry to en-
antiomerically pure cyclohexadienyl complexes.
As mentioned previously, the chemistry of discrete cyclohex-
adienyl metal complexes (especially ruthenium complexes)
derived from (η6-arene) precursors has not been extensively
developed.5 The preparative route to structurally elaborate
cyclohexadienyl complexes described above has proven to be
straightforward and reasonably broad in scope, features that
may spur additional investigations into the reactivity of these
materials. In this context we have briefly examined oxidative
demetalation of selected substrates with the aim of obtaining
heterocyclic synthetic building blocks. As shown in Scheme 3,
exposure of complexes 2 and 12e,f to previously established
oxidative demetalation reaction conditions afforded rearo-
matizedproducts arisingfrom cleavage of the spirolactam and
(14) Basavaiah, D.; Rao, A. J.; Satyanarayana, T. Chem. Rev. 2003,
103, 811.
(13) These bond distances are similar to other structurally character-
ized cyclohexadienyl ruthenium complexes. See refs 5c-5e and: Pigge,
F. C.; Coniglio, J. J.; Rath, N. P. Organometallics 2005, 24, 5424.
(15) For example both antipodes of enantiomerically enriched
1-aminoindane and 1-aminotetraline are commercially available
(Aldrich).

Article
Organometallics, Vol. 28, No. 13, 2009 3873
Experimental Section
2.88 (s, 2.5H), 2.96-2.99 (m, 1H), 3.04 (s, 0.5H), 3.31-3.43 (m, 1H),
5.52 (s, 5H), 5.76-5.80 (m, 1H), 5.93 (s, 0.8H), 6.08 (s, 0.2H), 6.18-
6.24 (m, 2H), 6.47-6.49 (m, 1H), 6.55-6.57 (m, 1H). 13C NMR
(acetone-d6): δ 19.5, 19.7, 25.7, 31.0, 32.2, 54.7, 58.7, 65.4, 81.0, 81.4,
82.8, 83.0, 83.2, 83.5, 83.9, 85.0, 86.3, 106.1, 109.6, 118.0, 147.8, 167.7.
Anal. Calcd for C20H24NORuPF6: C, 44.45; H, 4.48; N, 2.59. Found:
C, 44.27, H, 4.49, N, 2.66.
Arene Complex 11c. White solid, 83%, ∼5:1 mixture of insepar-
able diastereomers. 1H NMR (acetone-d6, mixture of rotamers):
δ 1.36 (dd, 0.5H, J1 = 2.1 Hz, J2 = 6.6 Hz), 1.44 (d, 2.5H, J =
7.2 Hz), 1.77-1.84 (m, 1H), 1.87 (dd, 3H, J1 = 1.2 Hz, J2 = 6.9 Hz),
2.83 (s, 0.5H), 2.85 (s, 2.5H), 2.99-3.04 (m, 1.6H), 3.12-3.13
(m, 0.4H), 3.52-3.59 (m, 1H), 5.48 (s, 4.18H), 5.62 (s, 0.82H),
5.93-5.95 (m, 1H), 6.18-6.23 (m, 2H), 6.46-6.48 (m, 1H), 6.49-
6.66 (m, 1H), 6.80-6.87 (m, 1H). 13C NMR (acetone-d6): δ 18.2, 21.3,
33.5, 37.9, 60.8, 81.5, 82.3, 82.5, 83.4, 85.03, 85.05, 85.2, 85.4, 108.5,
108.6, 113.3, 122.9, 123.1, 142.6, 142.8, 166.9, 167.0. Anal. Calcd
for C20H24NORuPF6: C, 44.45; H, 4.48; N, 2.59. Found: C, 44.36;
H, 4.41; N, 2.55.
All reactions were performed in oven-dried glassware under a
blanket of dry argon unless otherwise noted. Reagents purchased
from commercial sources were used as received. Solvents were
distilled from appropriate drying agents. 1H and 13C NMR
spectra were obtained at 300 and 75 MHz, respectively.
Chemical shifts (δ) are reported relative to TMS. IR spectra were
recorded onan FT-IR spectrophotometer equipped withan ATR
attachment. Melting points were determined using a capillary
melting point apparatus and are uncorrected. High-resolution
mass spectra were obtained using electron impact ionization (EI).
All arene ligands were prepared from commercially available
starting materials using routine functional group transforma-
tions. [CpRu(CH3CN)3][PF6] was prepared according to litera-
ture procedures.10
General Procedure for the Preparation of (η6-Arene)ruthenium
complexes. The preparation of 9a is representative. The arene ligand
(189 mg, 1.0 mmol) and [CpRu(CH3CN)3][PF6] (477 mg, 1.1 mmol)
were combined in 20 mL of 1,2-dichloroethane. The solution was
heated to 70 °C for 36 h. After cooling to rt the solvent was evaporated
and the residue was dissolved in acetone and passed through a short
column of neutral alumina. The filtrate was concentrated, then
redissolved in a minimum amount of acetone. Slow addition
of anhydrous ether resulted in precipitation of 9a as a colorless solid
that was collected by filtration and dried under vacuum. Yield:
Arene Complex 11d. White solid, 78%, mp 177-179 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.86 (dd, 3H, J1 = 1.6 Hz,
J2 = 6.9 Hz), 2.86 (br s, 1.5H), 2.96 (br s, 2.5H), 4.75-4.82 (m, 2H),
5.57 (s, 5H), 5.94-5.96 (m, 1H), 6.05-6.11 (m, 1H), 6.22-6.33
(m, 1H), 6.45-6.56 (m, 2H), 6.80-6.87 (m, 1H). 13C NMR (acetone-
d6): 18.0, 56.8, 72.8, 76.7, 81.1, 81.6, 82.5, 83.3, 84.7, 86.9, 122.5, 143.2,
158.8, 167.1. Anal. Calcd for C18H20NO2RuPF6: C, 40.92; H, 3.82;
N, 2.65. Found: C, 41.09; H, 3.75; N, 2.28.
1
350 mg (70%). Mp: 172-173 °C. H NMR (acetone-d6, mixture of
Arene Complex 11e. White solid, 88%, mp 203-206 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.88 (dd, 3H, J1 = 1.6 Hz,
J2 = 6.9 Hz), 1.98-2.00 (m, 2H), 2.11-2.12 (m, 1H), 2.68-2.77
(m, 1H), 2.95-3.00 (m, 1H), 3.03 (s, 3H), 5.53 (s, 5H), 5.55-5.63
(m, 2H), 6.17-6.26 (m, 3H), 6.29-6.33 (m, 1H), 6.48 (d, 1H, J =
14.7 Hz), 6.79-6.89 (m, 1H). 13C NMR (acetone-d6): δ 17.4, 21.7,
25.9, 31.8, 53.7, 81.3, 81.5, 81.6, 85.0, 85.4, 102.8, 104.7, 122.2, 142.1,
166.3. Anal. Calcd for C20H24NORuPF6: C, 44.45; H, 4.48; N, 2.59.
Found: C, 44.88; H, 4.52; N, 2.76.
rotamers): δ 2.75-2.88 (m, 3.2H), 3.08 (s, 1.8H), 3.70 (t, 1.5H, J =
7.4 Hz), 3.77-3.82 (m, 0.5H), 5.63 (s, 5H), 5.65 (dd, 1H, J1 = 10.4 Hz,
J2 = 2.5 Hz), 6.14 (dd, 1H, J1 = 12.0 Hz, J2 = 4.4 Hz), 6.23-6.63
(m, 5H), 6.60-6.81 (m, 1H). 13C NMR (acetone-d6): δ 31.9, 35.2, 48.7,
80.8, 80.9, 85.2, 85.4, 85.8, 85.9, 87.1, 87.5, 104.2, 127.0, 128.4, 165.7.
Anal. Calcd for C17H20NORuPF6: C, 40.81; H, 4.03; N, 2.80. Found:
C, 40.89, H, 4.05, N, 2.87.
Arene Complex 9b. White solid, 74%, mp 165-167 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.71 (d, 0.5H, J = 6.7 Hz), 1.84
(d, 2.5H, J = 6.8 Hz), 2.75 (s, 1.2H), 2.88 (s, 1.8H), 3.74 (t, 1H,
J = 7.3 Hz), 4.17-4.21 (m, 1H), 4.36-4.42 (m, 1H), 5.55 (s, 5H),
6.26-6.29 (m, 5H), 6.54 (br s, 1H), 6.80 (m, 1H), 7.34-7.49 (m, 5H).
13C NMR (acetone-d6): δ 18.0, 37.2, 48.4, 54.0, 81.7, 85.9, 86.0, 87.2,
109.1, 122.7, 128.7, 129.2, 129.8, 141.8, 142.0, 166.8. Anal. Calcd for
Arene Complex 11f. White solid, 99%, mp 218-220 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.86-1.98 (m, 5H), 2.06-2.10
(m, 2H), 2.64-2.70 (m, 1H), 3.00 (s, 2.5H), 3.22 (s, 0.5H), 3.79-3.84
(m, 4H), 5.51 (s, 5H), 5.57 (s, 1H), 6.22-6.31 (m, 3H), 6.47 (d, 1H,
J = 14.1 Hz), 6.79-6.90 (m, 1H). 13C NMR (acetone-d6): δ 17.4, 21.8,
25.9, 26.4, 32.0, 54.0, 57.0, 72.8, 73.2, 80.4, 80.5, 81.0, 81.1, 81.3, 83.4,
86.3, 101.4, 101.7, 122.3, 133.9, 142.0, 166.3. Anal. Calcd for
C
24H26NORuPF6: C, 48.82; H, 4.44; N, 2.37. Found: C, 48.56, H,
4.49, N, 2.32.
Arene Complex 9c. White solid, 98%, mp 203-205 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.25-1.30 (m, 3H), 1.31-1.88
(m, 8H), 2.06-2.21 (m, 2H), 2.85 (s, 2.8H), 2.95 (s, 0.2H), 3.77 (s, 2H),
3.86 (s, 3H), 5.51 (s, 5H), 6.28-6.23 (m, 5H), 6.54-6.63 (m, 1H).
13C NMR (acetone-d6): δ 18.0, 22.6, 26.1, 34.3, 39.4, 40.9, 55.1, 57.6,
73.7, 80.8, 83.5, 115.0, 123.3, 134.9, 141.4, 167.7. Anal. Calcd for
C
21H26NO2RuPF6: C, 44.21; H, 4.59; N, 2.46. Found: C, 43.95; H,
4.53; N, 2.35.
Arene Complex 11g. White solid, 90%, mp 170-172 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.90 (dd, 3H, J1 = 1.7 Hz, J2 =
6.9 Hz), 1.93-1.97 (m, 3H), 2.06-2.11 (m, 1H), 2.69-2.79 (m, 2H),
2.90 (s, 3H), 3.84 (s, 3H), 3.86-3.88 (m, 1H), 5.53 (s, 5H), 5.57 (s, 1H),
6.13 (d, 1H, J = 6.4 Hz), 6.31 (d, 1H, J = 6.4 Hz), 6.49 (d, 1H, J =
15.0 Hz), 6.85-6.91 (m, 1H). 13C NMR (acetone-d6): δ 17.4, 21.8,
26.0, 31.8, 53.4, 57.0, 73.4, 73.9, 80.5, 81.0, 81.2, 82.4, 99.8, 103.1,
133.9, 142.0, 166.2. Anal. Calcd for C21H26NO2RuPF6: C, 44.21;
H, 4.59; N, 2.46. Found: C, 43.76; H, 4.50; N, 2.41.
C24H32NO2RuPF6: C, 47.06; H, 5.27; N, 2.29. Found: C, 47.08;
H, 5.40; N, 2.23.
Arene Complex 9d. White solid, 82%, mp 210-212 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.66-2.00 (m, 6H), 2.79-3.02
(m, 5H), 3.11-3.23 (m, 2H), 3.36-3.62 (m, 1H), 3.76-3.94 (m, 1H),
5.49 (s, 2.5 H), 5.58 (s, 2.5H), 6.15-6.37 (m, 4H), 6.49-6.55 (m, 1H),
6.75-6.89 (m, 1H). 13C NMR (acetone-d6): δ 18.0, 19.9, 25.5, 32.5,
36.0, 52.8, 54.0, 80.6, 81.1, 81.2, 81.3, 84.3, 84.5, 85.1, 104.2, 107.4,
141.5, 167.6. Anal. Calcd for C21H26NORuPF6: C, 45.66; H, 4.38; N,
2.54. Found: C, 45.46; H, 4.80; N, 2.66.
General Procedure for Preparation of (η5-Cyclohexadienyl)
ruthenium Complexes. The procedure used for the synthesis of 10a
is representative. A solution of 9a (200 mg, 0.4 mmol), Bu3P (80 mg,
0.4 mmol), and NaH (60%, 32 mg, 0.8 mmol) in 1,2-dimethoxyethane
(DME, 10 mL) was stirred at rt for 12 h. The solvent was evaporated,
and the residue was partitioned between CH2Cl2 and brine. The
organic phase was separated, dried over anhydrous Na2SO4, filtered,
and concentrated. The residue was purified by flash column chroma-
tography (SiO2, 1:1 hexanes/EtOAc) to afford 10a (126 mg, 89%) as a
yellow solid. Mp: 181-183 °C. 1H NMR (CDCl3): δ 2.15 (t, 2H, J =
6.4 Hz), 2.63 (d, 2H, J = 6.4 Hz), 2.93 (s, 3H), 3.40 (t, 2H, J = 6.4 Hz),
4.51 (t, 2H, J = 5.6 Hz), 4.72 (s, 5H), 4.95 (d, 1H, J = 2.2 Hz), 5.70
(t, 1H, J = 4.8 Hz), 5.82 (d, 1H, J = 2.2 Hz). 13C NMR (CDCl3):
δ 34.6, 35.0, 36.8, 43.8, 45.80, 75.6, 76.8, 80.4, 119.5, 148.2, 164.1. IR
(neat): ν (cm-1) 1651. HRMS (EI): calcd for C17H19NORu 354.0437
[M]+, found 354.0432.
Arene Complex 11a. White solid, 87%, mp 145-147 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.87 (dd, 3H, J1 = 1.6 Hz,
J2 = 6.8 Hz), 2.14-2.23 (m, 1H), 2.81 (s, 3H), 3.02-3.08 (m, 3H),
3.34-3.46 (m, 1H), 5.58 (s, 5H), 5.77 (d, 1H, J = 8.1 Hz), 6.19-6.24
(m, 2H), 6.41-6.57 (m, 2H), 6.78-6.87 (m, 1H). 13C NMR (acetone-
d6): δ 19.9, 33.5, 34.3, 62.1, 83.5, 83.9, 85.5, 85.8, 85.9, 87.5, 87.6,
112.2, 124.8, 144.3, 168.2. Anal. Calcd for C19H22NORuPF6:
C, 43.35; H, 4.21; N, 2.66. Found: C, 43.31, H, 4.23, N, 2.68.
Arene Complex 11b. White solid, 83%, mp 135-137 °C. 1H NMR
(acetone-d6, mixture of rotamers): δ 1.83 (s, 2.5H), 1.89 (s, 0.5H),
1.91 (s, 2.5H), 2.04 (s, 0.5H), 2.12-2.25 (m, 1H), 2.56-2.27 (m, 1H),

3874 Organometallics, Vol. 28, No. 13, 2009
Pigge et al.
Cyclohexadienyl Complex 10b. Yellow solid, 48%, mp 222-
224 °C. 1H NMR (CDCl3): δ 1.87 (d, 3H, J = 7.1 Hz), 2.21 (d, 1H, J =
7.5 Hz), 2.94 (s, 3H), 2.95 (d, 1H, J = 7.5 Hz), 3.34 (d, 1H, J = 13.0 Hz),
3.80 (d, 1H, J = 7.2 Hz), 3.90-3.96 (m, 1H), 4.39 (t, 1H, J = 5.5 Hz),
4.52 (t, 1H, J = 5.5 Hz), 4.84 (s, 5H), 5.60 (q, 1H, J = 7.1 Hz), 5.62
(t, 1H, J = 4.8 Hz), 7.01-7.04 (m, 2H), 7.22-7.26 (m, 3H). 13C NMR
(CDCl3): δ 15.3, 32.3, 34.2, 36.8, 49.9, 50.6, 52.7, 65.8, 75.7, 80.6, 127.0,
128.0, 129.2, 134.1, 138.1, 142.4, 165.4. IR (neat): ν (cm-1) 1661. HRMS
(EI): calcd for C24H25NORu 444.0907 [M]+, found 444.0901.
Cyclohexadienyl Complex 10c. Yellow solid, 75%, mp 142-
144 °C. 1H NMR (CDCl3): δ 0.88-1.77 (m, 10H), 1.76 (d, 3H, J =
5.0 Hz), 2.03 (d, 1H, J = 14.0 Hz), 2.93 (s, 3H), 3.25 (d, 1H, J = 14.0 Hz),
3.29 (s, 3H), 3.46 (br s, 2H), 4.45 (d, 1H, J = 4.5 Hz), 4.73 (s, 5H), 5.64
(d, 1H, J = 4.5 Hz) 5.70 (q, 1H, J = 5.0 Hz). 13C NMR (CDCl3): δ 14.2,
22.1, 22.6, 23.6, 26.6, 28.3, 37.2, 38.9, 40.4, 40.8, 53.25, 53.31, 54.7, 66.1,
71.9, 75.9, 127.5, 128.4, 147.3, 172.6. IR (neat): ν (cm-1) 1655. HRMS
(EI): calcd for C24H30NO2Ru 466.1320 [M - H]+, found 466.1328.
Cyclohexadienyl Complex 10d. Yellow solid, 50%, mp 156-
158 °C. 1H NMR (CDCl3): δ 1.58-1.62 (m, 4H), 1.87 (d, 3H, J =
7.1 Hz), 1.89-1.96 (m, 3H), 2.85 (d, 1H, J = 6.4 Hz), 2.88 (s, 3H), 3.09
(d, 1H, J = 13.1 Hz), 3.38 (d, 1H, J = 13.2 Hz), 4.45 (t, 1H, J = 5.6 Hz),
4.58 (d, 1H, J = 4.7 Hz), 4.81 (s, 5H), 5.43 (q, 1H, J = 7.1 Hz), 5.66
(t, 1H, J = 4.8 Hz). 13C NMR (CDCl3): δ 15.5, 26.0, 29.2, 31.1, 34.1,
38.0, 43.1, 49.5, 52.4, 75.7, 75.5, 76.0, 78.1, 78.5, 134.3, 135.6. IR (neat):
ν (cm-1) 1646. HRMS (EI): calcd for C21H25NORu 409.0978 [M]+,
found 409.0980.
Cyclohexadienyl Complex 12a. Yellow solid, 59%, mp 167-
169 °C. 1H NMR (CDCl3): δ 1.53-1.74 (m, 1H), 1.80-1.89 (m, 2H),
2.02 (d, 3H, J = 7.2 Hz), 2.27-2.33 (m, 1H), 2.83 (d, 1H, J = 6.0 Hz),
2.86 (s, 3H), 3.80 (d, 1H, J = 7.5 Hz), 4.35 (t, 1H, J = 2.7 Hz), 4.58
(d, 1H, J = 4.5 Hz), 4.71 (s, 5H), 5.61 (t, 1H, J= 4.7 Hz), 5.70 (q, 1H, J =
7.4 Hz). 13C NMR (CDCl3): δ 12.7, 27.9, 30.3, 31.0, 33.7, 52.7, 59.2,
70.8, 71.6, 73.5, 76.0, 133.6, 140.9, 167.7. IR (neat): ν (cm-1) 1679.
Anal. Calcd for C19H21NORu: C, 59.98; H, 5.56; N, 3.68. Found:
C, 59.59; H, 5.43; N, 3.89.
Cyclohexadienyl Complex 12b. Obtained as a separable mixture
of alkene isomers. r,β-isomer: Yellow solid, 27%, mp 162-164 °C.
1H NMR (CDCl3): δ 1.51-1.60 (m, 2H), 1.69 (s, 3H), 2.02 (d, 2H, J =
7.2 Hz), 2.14 (s, 3H), 2.85-2.90 (m, 1H), 2.91 (s, 3H), 4.23 (dd, 1H,
J1 = 3.3 Hz, J2 = 8.9 Hz), 4.35 (t, 1H, J = 5.4 Hz), 4.71 (s, 5H), 4.78
(d, 1H, J = 4.5 Hz), 5.66 (t, 1H, J = 4.7 Hz). 13C NMR (CDCl3):
δ 13.3, 22.6, 25.1, 29.0, 30.0, 31.6, 34.3, 39.7, 55.6, 60.9, 76.2, 75.4,
75.7, 75.5, 76.3, 133.0, 134.2, 168.9. IR (neat): ν (cm-1) 1679.
Anal. Calcd for C20H23NORu: C, 60.90; H, 5.88; N, 3.55. Found:
C, 60.97; H, 5.89; N, 3.58. β,γ-isomer: Pale yellow solid, 27%,
mp 174-176 °C. 1H NMR (CDCl3): δ 1.59 (s, 3H), 1.61-1.71
(m, 2H), 1.82-2.05 (m, 2H), 2.15 (s, 1H), 2.17-2.65 (m, 1H), 2.66
(d, 1H, J = 6.0 Hz), 2.83 (s, 3H), 3.88 (d, 1H, J = 6.5 Hz), 4.36 (t, 1H,
J = 5.7 Hz), 4.61 (s, 1H), 4.67 (s, 5H), 4.93 (s, 1H), 5.46 (t, 1H, J =
4.8 Hz). 13C NMR (CDCl3): δ 19.6, 21.0, 22.5, 25.8, 28.3, 30.8, 31.5,
53.0, 55.6, 65.5, 71.5, 71.8, 75.4, 76.4, 77.6, 116.9, 118.3, 141.2, 173.9.
IR (neat): ν (cm-1) 1667. Anal. Calcd for C20H23NORu: C, 60.90; H,
5.88; N, 3.55. Found: C, 60.89; H, 5.91; N, 3.65.
28.6, 36.3, 55.6, 62.6, 69.3, 71.8, 72.5, 73.9, 76.0, 97.3, 135.9, 139.9,
167.6. IR (neat): ν (cm-1) 1676. HRMS (EI): calcd for C18H19NO2Ru
381.0458 [M]+, found 381.0443.
Cyclohexadienyl Complex 12e. Yellow solid, 58%, mp 152-
1
154 °C. H NMR (CDCl3): δ 1.57-1.75 (m, 5H), 1.96 (d, 3H, J =
7.2 Hz), 2.09-2.13 (m, 1H), 2.67 (d, 1H, J = 6.0 Hz), 2.87 (s, 3H),
3.29-3.38 (m, 1H), 4.12 (t, 1H, J = 5.3 Hz), 4.57 (d, 1H, J = 4.5 Hz),
4.77 (s, 5H), 5.35 (q, 1H, J = 7.4 Hz), 5.60 (t, 1H, J = 4.7 Hz).
13C NMR (CDCl3): δ 13.8, 14.7, 24.5, 28.7, 30.4, 31.9, 40.0, 47.8, 50.7,
68.4, 75.4, 78.9, 131.0, 138.3, 168.2. IR (neat): ν (cm-1) 1676. Anal.
Calcd for C20H23NORu: C, 60.90; H, 5.88; N, 3.55. Found: C, 61.37;
H, 6.39; N, 3.24.
Cyclohexadienyl Complex 12f. Yellow solid, 62%, mp 148-
150 °C. 1H NMR (CDCl3): δ 1.26-1.78 (m, 5H), 1.98 (d, 3H, J =
7.5 Hz), 2.06-2.15 (m, 1H), 2.92 (s, 3H), 3.02 (s, 1H), 3.23 (s, 3H), 3.39-
3.45 (m, 1H), 4.56 (d, 1H, J = 5.1 Hz), 4.78 (s, 5H), 5.39 (q, 1H, J =
7.2 Hz), 5.72 (d, 1H, J = 4.8 Hz). 13C NMR (CDCl3): δ 13.1, 23.8, 28.0,
29.6, 30.1, 30.5, 46.8, 52.2, 55.1, 67.1, 67.7, 73.7, 75.7, 127.7, 130.7, 136.9,
167.5. IR (neat): ν (cm-1) 1666. Anal. Calcd for C21H25NO2Ru: C,
59.42; H, 5.94; N, 3.30. Found: C, 59.50; H, 5.99; N, 3.21.
Cyclohexadienyl Complex 12g. Yellow solid, 58%, mp 177-
1
179 °C. H NMR (CDCl3): δ 1.22-1.72 (m, 6H), 1.97 (d, 3H, J =
7.2 Hz), 2.07-2.13 (m, 1H), 2.46 (d, 1H, J = 6.0 Hz), 2.88 (s, 3H),
3.27-3.38 (m, 1H), 3.63 (s, 3H), 4.32 (d, 1H, J = 6.0 Hz), 4.81 (s, 5H),
5.44 (q, 1H, J = 7.2 Hz). 13C NMR (CDCl3): δ 13.8, 24.4, 28.7, 30.3,
31.8, 34.6, 42.1, 58.1, 64.1, 67.8, 69.5, 77.3, 131.0, 132.2, 138.0, 168.2.
IR (neat): ν (cm-1) 1666. Anal. Calcd for C21H25NO2Ru: C, 59.42; H,
5.94; N, 3.30. Found: C, 59.46; H, 6.06; N, 3.40.
3-Benzazepine 17. A solution of cyclohexadienyl complex 29
(78 mg, 0.21 mmol) in ∼3 mL of THF was placed under a CO
atmosphere (balloon). Copper(II) bromide (135 mg, 0.60 mmol) in
∼1 mL of H2O was added slowly via syringe. The resulting dark
reaction mixture was maintained at rt for 3 h. The solvent was
removed in vacuo, and the residue was dissolved in CH2Cl2, washed
with brine, dried over anhydrous MgSO4, filtered, and concentrated
to afford a yellow residue. Purification by flash column chromato-
graphy (SiO2, EtOAc) gave 55 mg (88%) of CpRu(CO)2Br16
20 (eluting first) along with 42 mg (98%) of benzazepine 17 as a
white solid. Mp: 116-118 °C. 1H NMR (CDCl3): δ 2.05 (d, 3H, J =
7.0 Hz), 3.01-3.13 (m, 5H), 3.62-3.67 (m, 2H), 6.07 (q, 1H, J =
7.0 Hz). 7.22-7.38 (m, 4H). 13C NMR (CDCl3): δ 13.9, 32.1, 33.1,
47.8, 126.8, 127.8, 130.0, 130.1, 130.7, 135.0, 135.6, 139.9, 170.9.
IR (neat): ν (cm-1) 1658. Anal. Calcd for C13H15NO: C, 77.58;
H, 7.51; N, 6.96. Found: C, 77.53; H, 7.53; N, 6.98.
Tetrahydroisoquinolinone 18. This material was prepared in 66%
isolated yield from complex 12e using the procedure given above.
Mp: 130-132 °C. 1H NMR (CDCl3): δ 1.93-1.95 (m, 1H), 2.18
(d, 3H, 7.4 Hz), 2.33-2.34 (m, 2H), 2.41-2.46 (m, 2H), 2.99 (d, 1H,
J = 3.8 Hz), 3.06 (s, 3H), 3.91 (m, 1H, 3.9 Hz), 5.74 (q, 1H, J = 7.3 Hz),
6.24 (dd, 1H, J1 = 1.8 Hz, J2 = 9.8 Hz), 6.83-6.88 (m, 2H). 13C NMR
(CDCl3): δ 13.4, 24.3, 27.9, 32.1, 47.1, 60.0, 125.3, 127.9, 129.7, 137.9,
148.8, 149.7, 168.7. IR (neat): ν (cm-1) 1687. Satisfactory HRMS data
could not be obtained as the compound was observed to decompose
within several hours after isolation.
Cyclohexadienyl Complex 12c. Pale yellow oil, 53%, ∼2:1
mixture of inseparable diasteromers. 1H NMR (CDCl3): δ 0.76
(d, 1.5H, J = 5.7 Hz), 0.89 (d, 3H, J = 7.5 Hz), 1.52 (d, 1H, J =
13.2 Hz), 1.82-1.88 (m, 2H), 2.02 (d, 4.5H, J = 7.5 Hz), 2.17-2.22
(m, 1H), 2.46-2.53 (m, 1H), 2.82-2.85 (m, 2.5H), 2.89 (s, 3H), 3.67
(d, 0.5H, J = 6.9 Hz), 3.84 (d, 1H, J = 6.6 Hz), 4.28-4.32 (m, 1.5H),
4.42 (d, 0.5H, J = 4.5 Hz), 4.62 (d, 1H, J = 4.5 Hz), 4.61 (s, 5H), 4.63
(s, 2.5H), 5.62-5.75 (m, 3H). 13C NMR (CDCl3): δ 13.3, 14.8, 24.0,
28.03, 28.05, 29.9, 34.3, 34.8, 35.3, 37.9, 39.8, 42.3, 53.3, 54.0, 63.6,
67.8, 69.9, 71.3, 71.9, 72.3, 72.9, 73.7, 133.8, 133.9, 142.1, 143.5, 167.8,
168.4. IR (neat): ν (cm-1) 1647, 1673. HRMS (EI): calcd for
Tetrahydroisoquinoline 19. Isolated as an oil in 68% yield from
12f using the procedure given above. 1H NMR (CDCl3): δ 1.68-1.73
(m, 1H), 2.11-2.12 (m, 2H), 2.26 (d, 3H, J = 7.1 Hz), 2.53-2.86
(m, 3H), 2.88 (s, 3H), 3.91 (s, 3H), 4.62 (dd, 1H, J1 = 4.5 Hz, J2 =
12.3 Hz), 6.80 (q, 1H, J = 7.4 Hz), 7.01 (d, 1H, J = 8.8 Hz), 7.80
(d, 1H, J = 8.8 Hz). 13C NMR (CDCl3): δ 14.0, 16.5, 28.4, 28.9, 36.7,
54.6, 56.2, 111.3, 123.3, 123.4, 125.1, 128.1, 139.9, 140.0, 160.0. IR
(neat): ν (cm-1) 1682. Satisfactory HRMS data could not be obtained
as the compound was observed to decompose within several hours
after isolation.
20H23NORu 395.0827 [M]+, found 395.0823.
Tricyclic Spirolactam 21. Solid CuCl2 (46 mg, 0.35 mmol) was
added to a solution of 12g (60 mg, 0.14 mmol) in ∼3 mL of CH2Cl2.
The mixture was stirred at rt for 30 min. The dark-colored precipitate
was removed by filtration, and the filtrate was concentrated.
C
Cyclohexadienyl Complex 12d. Yellow solid, 59%, mp 177-
179 °C. 1H NMR (CDCl3): δ 2.01 (d, 3H, J = 7.2 Hz), 2.87 (s, 3H),
3.15 (d, 1H, J = 6.0 Hz), 3.82-3.87 (m, 1H), 3.96-4.03 (m, 2H), 4.22
(t, 1H, J = 2.9 Hz), 4.80 (s, 5H), 4.81 (d, 1H, J = 1.8 Hz), 5.42 (t, 1H,
J = 4.7 Hz), 5.75 (d, 1H, J = 7.5 Hz). 13C NMR (CDCl3): δ 13.1,
(16) Haines, R. J.; du Preez, A. L. J. Chem. Soc., Dalton Trans. 1972, 944.

Article
Organometallics, Vol. 28, No. 13, 2009 3875
Purification of the residue by flash column chromatography (SiO2,
EtOAc) afforded 21 (28 mg, 89%) as a white solid. Mp: 140-142 °C.
1H NMR (CDCl3): δ 1.60-1.73 (m, 4H), 2.19 (d, 3H, J = 7.4 Hz),
2.20-2.49 (m, 1H), 2.95 (s, 3H), 3.61-3.64 (m, 1H), 5.69 (q, 1H, J =
7.4 Hz), 6.15 (d, 1H, J = 9.8 Hz), 6.28 (s, 1H), 6.80 (d, 1H, J =
9.8 Hz). 13C NMR (CDCl3): δ 14.3, 18.5, 26.8, 28.9, 31.0, 50.3,
63.5, 126.4, 129.4, 131.0, 136.2, 151.8, 161.4, 167.7, 187.1. IR (neat):
ν (cm-1) 1655, 1685. Anal. Calcd for C15H17NO2: C, 74.05; H, 7.04;
N, 5.76. Found: C, 73.28; H, 7.00; N, 5.72.
Acknowledgment. We thank the U.S. National Science
Foundation for financial support (CHE-0544572),
and Dr. Venu R. Vangala for assistance with X-ray
crystallography.
Supporting Information Available: X-ray crystallographic
details for 12a (cif). Copies of NMR spectra for compounds
10a-d, 12a, 12c-e, 18, 19, and 21. This material is available free
of charge via the Internet at http://pubs.acs.org.