Friedel-crafts ring-coupling reactions promoted by tungsten dearomatization agent

Article abstract of DOI:10.1021/om3012008

The complexes TpW(NO)(PMe₃)(L), where L = phenol, N,N-dimethylanilinium, or naphthalene, undergo protonation followed by addition of an aromatic nucleophile. The addition of aromatic molecules occurs at the para carbon of the phenol or aniline

Full text of DOI:10.1021/om3012008

Article
pubs.acs.org/Organometallics
Friedel−Crafts Ring-Coupling Reactions Promoted by Tungsten
Dearomatization Agent
Jared A. Pienkos,†,⊥ Victor E. Zottig,†,⊥ Diana A. Iovan,‡ Mengxun Li,† Daniel P. Harrison,† Michal Sabat,§
Rebecca J. Salomon,† Laura Strausberg,† Victor A. Teran,† William H. Myers,‡ and W. Dean Harman*,†
†Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
‡Department of Chemistry, University of Richmond, Richmond, Virginia 27173, United States
§Nanoscale Materials Characterization Facility, Department of Materials Science and Engineering, University of Virginia,
Charlottesville, Virginia 22904, United States
S
* Supporting Information
ABSTRACT: The complexes TpW(NO)(PMe3)(L), where L
= phenol, N,N-dimethylanilinium, or naphthalene, undergo
protonation followed by addition of an aromatic nucleophile.
The addition of aromatic molecules occurs at the para carbon
of the phenol or aniline ring or the beta carbon of the
naphthalene. The addition occurs anti to the metal fragment,
as determined by X-ray crystallography. In the case where L =
phenol or N,N-dimethylanilinium, treatment of the bound
arene with an electrophilic heteroatom followed by an
aromatic nucleophile sets two stereocenters, with both
additions occurring anti to the metal. The resultant ligands
have been removed from the metal by oxidative decomplexation using ceric ammonium nitrate.
Scheme 1. Proposed Aromatic Coupling with η2-
Coordinated Arenes
INTRODUCTION
■
The Suzuki,1,2 Negishi,3−5 and Heck6−8 reactions have become
valuable methods for the coupling of two aromatic rings. Such
cross-coupling reactions typically result in the formation of a
new bond between two sp2 carbons.9,10 Cross-coupling
reactions that form an Csp2−Csp3 bond are also known, but
can be more difficult to perform,11−13 owing to undesired
eliminations and hydrodehalogenation reactions.14 A comple-
mentary ring-coupling procedure was envisioned between two
aromatic rings in which one was first activated (dearomatized)
via its dihapto-coordination to a π-basic metal. Protonation of
such an arene complex would create an electrophilic arenium
species that could react with a second aromatic molecule
through a Friedel−Crafts-type reaction mechanism, and a
subsequent deprotonation would regenerate the acid. The
product, after removal of the metal, would be a hydroarylated
arene. Alternatively, other electrophiles (E+) could be used in
place of protons if substituted cyclohexadienes were desired.
The general reaction sequence is proposed in Scheme 1, using
benzene for both arenes.
to the electrophilic partner of the coupling reaction, including
complexes of benzene (1), naphthalene (2), and anisole (3).
Complexes of phenol (4) and p-cresol (5) were included since
these arenes exist bound to the tungsten as their nonaromatic
2H-tautomers.16 Finally, 2H-arenium complexes derived from
anisole (6) and N,N-dimethylaniline (7) were also included in
the study, as these nonaromatic systems are structurally similar
to the phenol analogues. The seven arene-derived tungsten
complexes investigated are summarized in Figure 1.17−22
RESULTS AND DISCUSSION
■
Of the dihapto-coordinate dearomatization reagents available,
{TpW(NO)(PMe3)} is most economical,15 provides the
greatest degree of activation, and has a commercially available
precursor, TpW(NO)(Br)2. Several different types of η2-
coordinated arene complexes were considered as precursors
Received: December 11, 2012
Published: January 11, 2013
© 2013 American Chemical Society
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Scheme 2. Reactions with Naphthalene Complex 2 and
a
Various Aromatic Nucleophiles
Figure 1. η2-Arene-derived complexes for consideration as partners for
Friedel−Crafts reactions.
Solvents and Brønsted acid catalysts were varied to optimize
the addition of aromatic nucleophiles across the highlighted
double bond of 1−7. For the case of the benzene complex 1,
exposure to strong acids (e.g., CH3CN·HOTf) resulted in
significant decomposition judging from the appearance of
multiple peaks in the 31P NMR spectra. The use of weaker acids
as catalysts (e.g., diphenylammonium triflate (DPhAT),
camphorsulfonic acid, and 2,6-lutidinium triflate) resulted in
no reaction other than eventual ligand substitution. Attempts to
quantitatively protonate the benzene complex 1 in the presence
of an aromatic nucleophile led to either intractable mixtures of
products or decomposition, as indicated by 31P NMR data.
The naphthalene complex 2 was more tolerant of acids, and
the naphthalenium complex 8 could even be isolated at ambient
temperatures. Proton NMR data for the naphthalenium ligand
of complex 8 generally match that of the Re analogue,23 with
the exception of H4, whose peak appears considerably more
downfield for the W system owing to its “η2-allyl” character.21
When naphthalene complex 2 was stirred in a CHCl3 solution
of indole along with 0.1 equiv of the acid catalyst [Ph2NH2]-
OTf (DPhAT), the addition product 9 was obtained. Similar
results were observed with pyrrole to yield compound 10.
While furan failed to react with naphthalene complex 2 under
the conditions tested, 2-methyl- and 2,3-dimethylfuran were
both sufficiently nucleophilic to undergo ring-coupling. The
2,3-dimethylfuran-derived product 11 was chosen as an
example for full characterization. Parallel reactions with
nucleophilic benzenes such as anisole and aniline were not
observed. Successful ring-coupling reactions with naphthalene
complex 2 are summarized in Scheme 2.
a
[W] = TpW(NO)(PMe3).
HMBC and NOE data, along with chemical shifts of the
aromatic protons, confirm that the electrophilic addition occurs
at the alpha-carbon of these heterocycles. HMBC, COSY, and
NOE data further support the given structural and stereo-
chemical assignments in Scheme 2.18 A solid-state molecular
structure determination for the indolyldihydronaphthalene 9
confirms that the addition of the indole occurs anti to the
tungsten metal fragment (Figure 2).
Coordinated anisole, 3, exists as two coordination diaster-
eomers in which the methoxy group is either proximal or distal
to the PMe3 ligand. Treating 3 with catalytic acid (e.g., DPhAT
or CH3CN·HOTf) in the presence of an aromatic nucleophile
With regard to characterization of 9−11, the H2 signal
showed a strong NOE interaction with the PMe3 ligand, which
supports the assignment of nucleophilic addition anti to the
metal fragment. Data from multidimensional NMR experiments
indicated that the addition reactions to naphthalene 2 occurred
in a 1,2-fashion, rather than the 1,4-addition occasionally
observed with rhenium complexes.24 In the case of the pyrrole-
derived product 10, as well as the dimethylfuran analogue 11,
Figure 2. Solid-state molecular structure of the indolyldihydronap-
thalene product 9.
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resulted in the decomposition of the starting material: the 31P
signal observed for 3 was replaced with a new signal that
showed no 183W−31P coupling. Weaker acids failed to alter the
starting material. However, for the dearomatized 2H-phenol
complex (4), indole and pyrrole derivatives were found to add
across the C4−C5 double bond. A screen of substituted indole
complexes showed that substitution on the indolyl 3′-position
prevented this reaction, but substitution on the nitrogen or
biorelevant 5′-position was well tolerated (Scheme 3).
CH3CN·HOTf (Scheme 4). However, this allylic species failed
to react with any aromatic nucleophiles. Likely reasons for this
a
Scheme 4. Protonation of the p-Cresol Complex 5
Scheme 3. Reactions of Phenol Complex 4 with Various
Aromatic Nucleophiles
a
[W] = TpW(NO)(PMe3).
a
include an increased steric repulsion between the methyl group
and the Tp ligand upon the addition of a nucleophile and the
decreased electrophilicity of the allyl species due to the donor
methyl group.21
Quantitative protonation of anisole complex 3 forms 6, an
isolable, cationic species.25 Under the conditions tested,
compound 6 did not react cleanly with any aromatic
nucleophiles. Monitoring reactions between 6 and an aromatic
compound in different solvents showed in each case a
substantial amount of decomposition.
Attempts to quantitatively protonate complex 6 with
CH3CN·HOTf showed no reaction, as indicated by 31P NMR
spectra. Conditions involving catalytic acid, 6, and an excess of
an aromatic nucleophile were also unsuccessful in generating
clean product complexes.
a
[W] = TpW(NO)(PMe3).
As shown in the solid-state molecular structures of 12 and
13, the additions occurred both regio- and stereoselectively,
with the orientation of the nucleophile anti to the metal
complex (Figure 3).
In contrast to the phenol complex (4), the p-cresol analogue
5 underwent quantitative protonation with DPhAT or
The TpW(NO)(PMe3) complex of N,N-dimethylaniline is
not sufficiently stable to be isolated, but its conjugate acid 7 is
easily handled, even in air. While the bound 2H-anilinium
ligand is formally a cation, strong back-bonding from the
tungsten renders it capable of additional protonation.17 In the
presence of acid, 7 reacts with indole, pyrrole, activated furans,
and even 1,3-dimethoxybenzene and 1,3,5-trimethoxybenzene.
Of the nucleophiles that successfully reacted with anilinium
complex 7, 1,3-dimethoxybenzene appeared to be the least
activated.26 Various anisole derivatives and thiophenes showed
no reactivity with 7, as indicated by 31P NMR experiments.
These results are summarized in Scheme 5.
Electrophiles other than H+ are capable of reacting with
arene or arenium derivatives,17,27 and Friedel−Crafts reactions
Scheme 5. Reactions with Anilinium Complex 7 and Various
a
Aromatic Nucleophiles
Figure 3. Solid-state molecular structure of indole (12; top) and
pyrrole (13; bottom) addition products. Co-crystallized CHCl3 is
omitted for clarity from 12.
a
[W] = TpW(NO)(PMe3).
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to form more functionalized ring-coupling products were also
attempted.
Scheme 7. Electrophilic Hetereoatom Addition Followed by
Aromatic Nucleophilic Addition to Anilinium Complex 7
a
Phenol complex 4 and anilinium complex 7 were both found
to react with heteroatom electrophiles followed by the
stereospecific addition of aromatic nucleophiles to form cis-
γ,δ-disubstituted cyclohexenone derivatives. This reaction
sequence seemed to work best for the phenol complexes
(Scheme 6). Whereas the byproducts from Selectfluor and N-
Scheme 6. Electrophilic Heteroatom Addition Followed by
a
Aromatic Nucleophilic Addition to Phenol Complex 4
a
[W] = TpW(NO)(PMe3).
a
[W] = TpW(NO)(PMe3).
chlorosuccinimide did not seem to interfere with the Friedel−
Crafts reaction step, 3-chlorobenzoate (from mCPBA) was
apparently competitive.27 However, the oxygenated derivative
26 could be generated from phenol 4 using mCPBA, and
subsequent treatment with acid in the presence of indole
formed the desired 5-hydroxy-4-indolyl-substituted product 27
in 60% yield.
Figure 4. Solid-state molecular structure of the 5-chloro-4-arylated
derivative 32. Triflate counterion is omitted for clarity.
Similar to the reaction with the hydroxylated enone 26, by
starting with the previously reported 5-halo-4-methoxy
analogue of the anilinium system, 28 or 29, one could generate
clean ring-coupled products via a π-allyl intermediate (Scheme
7). This strategy prevented any complications that could occur
from the electrophile reacting with the aromatic nucleophile.
Indeed a one-pot, sequential addition of an electrophilic
reagent (e.g., Selectfluor), followed by an aromatic carbon
nucleophile, led to impurities in the isolated product.
A solid-state molecular structure of compound 32 confirms
the relative stereochemistry of the hetereoatom electrophile
and carbon nucleophile (Figure 4). Complexes 30 and 31 have
NOE interactions between signals of H4 and H5, and the
methine proton anti to the aromatic nucleophile (H4) has a
strong NOE interaction with the PMe3 ligand.
Interestingly, the methoxy groups in 32 are all nonequivalent,
an observation suggesting slow rotation of the bulky aryl ring
about the C4−C4′ axis on the NMR time scale.
In order to liberate the ring-coupled organic products,
various complexes described above were treated with a reagent
capable of oxidizing the tungsten. For enone complexes, either
ceric ammonium nitrate (CAN) or 2,3-dichloro-5,6-dicyano-
benzoquinone (DDQ) was sufficient, but for the iminium
analogues, the stronger oxidant CAN was required. In addition,
DDQ sometimes rearomatized the liberated product back to a
phenol. For example, the oxidation of 12 by DDQ afforded two
organic products, both the enone, 33, and the rearomatized
para-substituted phenol, 34, in a 1:1 ratio. Varying equivalents
of DDQ, concentration, temperature, solvent, and addition of
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base to the reaction failed to prevent the formation of the p-
indol-3-ylphenol impurity. In contrast, oxidation of 12 with
CAN did not produce any of the aromatic side product.
However, purification of 33 using basic alumina in the presence
of O2 effected its conversion to 34. Rearomatization was
avoided using silica, and 33 could be isolated in a 61% yield. 1H
NMR resonances from the uncoordinated double bond of 33
shifted downfield from 3.42 and 2.31 ppm in 12 to 7.13 and
6.16 ppm in 33. Multidimensional NMR data, along with
HRMS, confirmed the structural assignment of 33 as 4-(indol-
3-yl)cyclohex-2-enone (Scheme 8).
Scheme 9. Oxidative Decomplexation of
Dihydronaphthalenes 9−11
a
Scheme 8. Oxidative Decomplexation of Enones
a
[W] = TpW(NO)(PMe3).
addition of the aromatic nucleophile occurs at the para position,
reactivity that is not seen in the parent complex. To our
knowledge, none of the organic γ-substituted cyclohexenones
reported in this paper have been previously synthesized.
However, 33 closely resembles an advanced synthetic
intermediate patented for use as an antidepressant.28 In most
cases, naphthalene undergoes electrophilic addition reactions
preferentially at the 1-position. However, under thermody-
namic control or in the presence of a bulky electrophile, 2-
substitution is preferred.29 η2-Coordination of naphthalene with
the TpW(NO)(PMe3) metal fragment allows for selective
protonation at the 1-position, followed by nucleophilic addition
to the 2-position. Of the organic complexes made through this
strategy, only 38 has been previously synthesized: under
photochemical conditions, pyrrole and naphthalene are
reported to combine to produce 38 as one component of a
complex mixture of products.30
Unfortunately, the decomplexation conditions used for 33
did not work for the pyrrole analogue, and only phenol and
pyrrole were recovered. Further, using these conditions with
products containing halogens did not yield any clean organic
compounds.
Compared to enone complexes, iminium compounds 17−21
are oxidized at higher potentials. For these complexes, DDQ
fails to oxidize the tungsten, and CAN was employed. Thus,
compounds 20 and 21 were oxidized with CAN, and the
liberated iminiums were hydrolyzed in situ to form the 4-
arylated enones 35 and 36 in yields of 38% and 48%,
respectively (Scheme 8). Oxidative decomplexation failed to
generate clean organic products from the halide derivatives
(22−25 or 30−32).
Dihydronaphthalene derivatives 9−11, having lower W(I/0)
reduction potentials than the enone or eniminium complexes,
readily oxidized in the presence of CAN, as shown in Scheme 9.
Treating 9−11 with one equivalent of CAN produced the
organic products 37−39 with yields of 61%, 28%, and 47%,
respectively. NOE and COSY interactions between H1 and H2
of compounds 37−39 confirmed 1,2-addition in the liberated
dihydronapthalenes.
Whereas organic anilines and phenols react with electrophiles
at the ortho and para positions, coordination to the
TpW(NO)(PMe3) metal fragment allows the initial electro-
philic attack to occur at the meta position. The subsequent
Pioneering work by the Yamamoto,31 Maier,32 Miura,33 and
Buchwald34 groups demonstrated the ability to arylate the γ-
position of enones, generating products similar to some of
those synthesized in this report. This was accomplished by
using Pd-catalyzed coupling of the enone to an aryl bromide or
by trapping Sn-masked dienolates.31 In particular, Buchwald et
al. have generated compounds similar to compounds herein
with a quaternary center in the γ-position.12 However, most of
the reports involving palladium-mediated arylation of carbonyl
functional groups focus on α-arylation.35−37 γ-Substituted
cyclohexenones that do not contain a quaternary carbon in
the γ-position have also been synthesized directly through
conjugate addition to cyclohexenones, followed by ring
expansion,38 or by dehydrogenation of cyclohexenones.39,40
However, in no other cases are sp2−sp3 ring-coupled products
formed from aromatic precursors.
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(Pz3A), 144.56 (Pz3B), 143.20 (Pz3C), 138.38 (Pz5C), 138.35
(Pz5A), 138.17 (Pz5B), 136.61 (C9 or C10), 132.86 (C9 or C10),
131.25 (C7), 130.46 (C4), 129.73 (C5), 128.10 (C8), 126.88 (C6),
109.02 (Pz4C), 108.47 (Pz4B), 107.39 (Pz4A), 96.55 (C3), 72.15
(C2), 33.17 (C1), 12.85 (d, J = 32, PMe3).
CONCLUSION
■
A new method for coupling aromatic rings was explored in
which the bicyclic product is partially dearomatized. The
method utilizes a tungsten-activated arene prepared from the
commercially available precursor TpW(NO)Br2 (Sigma-Al-
drich), which, upon electrophilic activation, undergoes a
Friedel−Crafts-type addition of various electron-rich aromatic
rings. In all cases, the arylation is regio- and stereoselective.
Additionally, in the case of phenol- and aniline-derived
examples, the new C−C bond occurs with a reversal of the
natural polarization for these arenes.
TpW(NO)(PMe3)(3,4-η2-(3-(1,2-dihydronaphthalen-2-yl)-1H-in-
dole)) (9). Compound 2 (201 mg, 0.319 mmol), indole (178 mg, 1.521
mmol), and diphenylammonium triflate (10 mg, 0.031 mmol) were
weighed into a 4-dram vial. CHCl3 (4.982 g) was added to the vial, and
the reaction mixture was stirred for a week. Et2O (5 mL) was added to
precipitate a light beige precipitate, which was filtered on a 15 mL fine-
porosity fritted funnel as 9 (188 mg, 0.252 mmol, 79%).
1H NMR (d6-acetone): δ 9.67 (s, 1H, NH), 8.15 (d, 1H, J = 2.0,
Pz3B), 8.01 (d, 1H, J = 2.0, Pz5C), 7.96 (d, 1H, J = 2.0, Pz5B), 7.86
(d, 1H, J = 2.0, Pz5A), 7.79 (d, 1H, J = 7.6, H11), 7.71 (d, 1H, J = 2.0,
Pz3C), 7.39 (d, 1H, J = Pz3A), 7.35 (d, 1H, J = 7.9, H14), 7.08 (m,
1H, H15), 7.05 (m, 1H, H17), 7.02 (m, 1H, H16), 6.95 (t, 1H, J = 7.5,
H6), 6.76 (d, 1H, J = 7.3, H8), 6.68 (t, 1H, J = 7.3, H7), 6.61 (d, 1H, J
= 7.6, H5), 6.41 (t, 1H, J = 2.0, Pz4B), 6.36 (t, 1H, J = 2.0, Pz4C), 6.21
(t, 1H, J = 2.0, Pz4A), 4.59 (d, 1H, J = 6.1, H2), 3.74 (dd, 1H, J = 6.2,
15.4 H1), 3.30 (dd, 1H, J = 10.2, 12.6, H3), 2.66 (d, 1H, J = 15.8,
EXPERIMENTAL SECTION
■
General Methods. NMR spectra were obtained on either a 300,
500, or 600 MHz spectrometer (Varian INOVA or Bruker Avance).
All chemical shifts are reported in ppm. Proton and carbon shifts are
referenced to tetramethylsilane (TMS) utilizing residual H or 13C
1
signals of the deuterated solvent as an internal standard. Phosphorus
NMR signals are referenced to 85% H3PO4 (δ) 0.00 ppm using a
triphenylphosphate external standard in acetone (δ = −16.58 ppm).
Coupling constants (J) are reported in hertz (Hz). Infrared (IR)
spectra were recorded on a MIDAC Prospect Series (model PRS)
spectrometer as a glaze on a horizontal attenuated total reflectance
accessory (Pike Industries). Electrochemical experiments were
performed under a dinitrogen atmosphere using a BAS Epsilon EC-
2000 potentiostat. Cyclic voltammetry data were taken at ambient
temperature at 100 mV/s in a standard three-electrode cell with a
glassy carbon working electrode using tetrabutylammonium hexa-
fluorophosphate as an electrolyte [approximately 0.5 M in
dimethylacetamide (DMA)] unless otherwise noted. All potentials
are reported versus the normal hydrogen electrode using cobaltoce-
nium hexafluorophosphate (E1/2 = −0.78 V), ferrocene (E1/2 = +0.55
V), or decamethylferrocene (E1/2 = +0.04 V) as an internal standard.
The peak-to-peak separation was 100 mV or less for all reversible
couples. High-resolution electrospray ionization mass spectrometry
(ESI-MS) analyses were obtained on a Bruker BioTOF-Q instrument
running in ESI mode from samples dissolved in 1:3 water/acetonitrile
solution containing sodium trifluoroacetate (NaTFA), and using
[Na(NaTFA)x]+ clusters as an internal standard. For metal complexes,
these data are reported using the five most intense peaks from the
isotopic envelope for either M+ (for monocationic complexes) or [M +
H]+ or [M + Na]+ (for neutral complexes). The data are listed as m/z
with the intensity relative to the most abundant peak of the isotopic
envelope given in parentheses for both the calculated and observed
peaks. The difference between calculated and observed peaks is
reported in ppm. For organic species, the calculated and observed
peaks for [M + H]+ or [M + Na]+ are reported, with the difference
between them reported in ppm. LRMS data were acquired on a
Shimadzu G-17A/QP-5050 GC-MS instrument operating either in
GC-MS or in direct inlet/MS mode. Mass spectra are reported as M+
for neutral or monocationic samples. In all cases, observed isotopic
envelopes were consistent with the molecular composition reported.
The data are listed as m/z with the intensity relative to the most
abundant peak of the isotopic envelope given in parentheses for both
the calculated and observed peaks.
H1′), 2.24 (dd, 1H, J = 1.8, 10.2, H4), 1.39 (d, 9H, J = 8.3, PMe3). 13
C
NMR (d6-acetone): δ 146.7 (s, C9), 144.5 (s, Pz3A), 144.3 (s, Pz3B),
142.0 (s, Pz3C), 138.0 (s, Pz5C), 137.8 (s, C18), 137.6 (s, C13), 137.2
(s, Pz5B), 136.7 (s, Pz5A), 133.9 (s, C10), 129.6 (s, C12), 129.6 (s,
C8), 129.5 (s, C5), 124.7 (s, C6), 123.4 (s, C16), 123.2 (s, C7), 121.8
(s, C15), 119.5 (s, C11), 119.4 (s, C17), 112.2 (s, C14), 107.4 (s,
Pz4B), 107.2 (s, Pz4C), 106.0 (s, Pz4A), 63.9 (s, C3), 55.1 (s, C4),
37.9 (s, C2), 36.0 (s, C1), 13.5 (d, J = 28, PMe3). 31P NMR (d6-
acetone): δ −8.62 (JP−W = 281 Hz). CV (DMA): Ep,a = +0.488 V. IR:
νNO = 1550 cm−1. HRMS (M + Na)+ obsd (%), calcd (%), ppm:
769.20481 (83.1), 769.20715 (80.1), −3; 770.2098 (81.3), 770.20965
(81.8), 0.2; 771.20731 (100), 771.20967 (100), −3.1; 772.21193
(50.7), 772.21345 (48.7), −2; 773.20883 (76.2), 773.21287 (81.9),
−5.2.
TpW(NO)(PMe3)(3,4-η2-(2-(1,2-dihydronaphthalen-2-yl)-1H-pyr-
role)) (10). Compound 2 (150 mg, 0.238 mmol) and camphorsulfonic
acid (15 mg, 0.065 mmol) were weighed into a 4-dram vial. CHCl3
(1.531 g) and pyrrole (102 mg, 1.52 mmol) were added, and after
stirring, the solution was allowed to stand for 2.5 h. The vial was
removed from the glovebox, and the solution was diluted with 30 mL
of dichloromethane (DCM) and extracted with 10 mL of saturated
aqueous NaHCO3 solution. The aqueous layer was back-extracted with
5 mL of DCM. The organic layer was extracted twice with 10 mL
portions of water, each of which was back-extracted with DCM (5
mL). The combined organic layer was dried over anhydrous MgSO4
and filtered on a 60 mL medium-porosity fritted funnel. The filtrate
was concentrated in vacuo. The brown oil was redissolved in minimal
DCM and added to a stirring solution of hexanes (30 mL). The pale
tan solid that precipitated was collected on a 15 mL fine-porosity
fritted funnel to give 10 (128 mg, 0.183 mmol, 77%).
1H NMR (CDCl3): δ 8.05 (d, 1H, J = 2.0, Pz3B), 7.87 (br s, 1H,
NH), 7.75 (d, 1H, J = 2.0, Pz5C), 7.71 (d, 1H, J = 2.0, pz5B), 7.63 (d,
1H, J = 2.0, Pz5A), 7.39 (d, 1H, J = 2.0, Pz3C), 7.33 (d, 1H, J = 2.0,
pz3A), 7.07 (m, 2H, H6 and H8), 6.88 (t, 1H, J = 7.5, H7), 6.66 (d,
1H, J = 7.5, H5), 6.46 (m, 1H, H14), 6.29 (t, 1H, J = 2.0, Pz4B), 6.20
(t, 1H, J = 2.0, Pz4C), 6.12 (t, 1H, J = 2.0, Pz4A), 6.08 (m, 1H, H13),
5.99 (m, 1H, H12), 4.17 (d, 1H, J = 6.5, H2), 3.59 (dd, 1H, J = 6.7,
15.9, H1), 3.03 (dd, 1H, J = 10.3, 12.5, H3), 2.71 (dd, 1H, J = 6.7,
15.9, H1′), 2.14 (dd, 1H, J = 1.8, 10.3, H4), 1.33 (d, 9H, J = 8.1,
PMe3). 13C NMR (CDCl3): δ 144.7 (s, C9), 144.0 (s, pz3A), 143.4 (s,
C11), 143.1 (s, Pz3B), 140.6 (s, Pz3C), 136.7 (s, Pz5C), 136.1 (s,
Pz5B), 135.4 (s, Pz5A), 132.4 (s, C10), 129.1 (s, C5), 129.1 (s, C8),
124.5 (s, C6), 123.5 (s, C7), 116.6 (s, C14), 106.9 (s, C13), 106.9 (s,
Pz4B), 106.0 (s, Pz4C), 105.4 (s, Pz4A), 102.5 (s, C12), 62.5 (s, C3),
53.5 (s, C4), 39.3 (s, C2), 34.5 (s, C1), 13.6 (d, J = 28, PMe3). 31P
NMR (CDCl3): δ −9.36 (JP−W = 280 Hz). CV (DMA): Ep,a = +0.533
V. IR: νNO = 1535 cm−1. HRMS (M + Na)+ obsd (%), calcd (%), ppm:
719.19051 (65.1), 719.19144 (82.2), −1.3; 720.19459 (67.6),
720.19397 (81.2), 0.9; 721.19485 (100), 721.1939 (100), 1.3;
Allyl Compound 8. Triflic acid (22 mg, 0.147 mmol) in CHCl3
(1.52 g) was added to 2 (51 mg, 0.081 mmol). The resulting orange
solution was precipitated over stirring ether (16 mL) and filtered
through a 15 mL medium-porosity fritted funnel to give 8 as an orange
solid (53 mg, 84%).
1H NMR (CDCl3): δ 8.24 (d, J = 2.0, 1H, Pz3C), 8.06 (d, J = 2.0,
1H, Pz3B), 8.04 (d, J = 2.0, 1H, Pz3A), 7.89 (d, J = 2.0, 1H, Pz5C),
7.81 (d, J = 2.0, 1H, Pz5B), 7.72 (d, J = 2.0, 1H, Pz5A), 7.39 (d, J =
7.5, 1H, H5), 7.29 (m, 1H, H6), 7.17 (m, 1H, H7), 7.16 (m, 1H, H8),
6.71 (d, J = 7.2, 1H, H4), 6.59 (t, J = 2.0, 1H, Pz4C), 6.39 (t, J = 2.0,
1H, Pz4B), 6.34 (t, J = 2.0, 1H, Pz4A), 5.12 (dd, J = 20.7, 5.6, 1H,
H1), 5.04 (m, 1H, H2), 4.95 (t, J = 7.3, 1H, H3), 3.83 (d, J = 20.5, 1H,
H1′), 1.23 (d, J = 9.4, 9H, PMe3). 13C NMR (CDCl3): δ 147.09
696
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Organometallics
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722.19681 (47.3), 722.19785 (46), −1.4; 723.19812 (81.5), 723.19712
(82.7), 1.4.
35.5 (s, C4), 34.2 (s, C6), 30.2 (s, C5), 13.8 (d, J = 28.8, PMe3). 31P
NMR (CDCl3): δ −7.99 (JP−W = 284 Hz). CV: Ep,a = +0.84 V. IR: νBH
= 2484 cm−1, νCO = 1601 cm−1, νNO = 1562 cm−1. HRMS: [M + H]+
obsd (%), calcd (%), ppm: 713.20422 (89.3), 713.20441 (82.1), −0.3;
714.20582 (89.2), 714.20694 (81.1), −1.6; 715.20631 (92.2),
715.20688 (100), −0.8; 716.20988 (44.6), 716.21082 (46.1), −1.3;
717.21011 (100), 717.2101 (82.8), 0.0.
TpW(NO)(PMe3)(3,4-η2-(5-(1,2-dihydronaphthalen-2-yl)-2,3-di-
methylfuran)) (11). Compound 2 (101 mg, 0.160 mmol) and
camphorsulfonic acid (16 mg, 0.070 mmol) were weighed into a vial
and dissolved in CHCl3 (1.006 g). 2,3-Dimethylfuran (59 mg, 0.615
mmol) was added to the solution, and the reaction was allowed to
stand for 3 h. The vial was removed from the glovebox, and the
solution was diluted with DCM (20 mL) and extracted with 5 mL of a
saturated aqueous NaHCO3 solution. The aqueous layer was back-
extracted with 5 mL of DCM. The DCM solution was extracted twice
with 10 mL portions of water, each of which was back-extracted with
DCM (5 mL). The combined organic layers were dried over
anhydrous MgSO4, filtered on a 60 mL medium-porosity fritted
funnel, and concentrated in vacuo. The brown residue was taken into a
glovebox, dissolved in minimal DCM, and precipitated in stirring
hexanes (30 mL). The mixture was filtered on a 15 mL fine-porosity
fritted funnel to give 11 as a light tan solid (68 mg, 0.094 mmol, 59%).
1H NMR (CDCl3): δ 8.09 (d, 1H, J = 2.0, Pz3B), 8.00 (d, 1H, J =
2.0, Pz5C), 7.94 (d, 1H, J = 2.0, Pz5B), 7.82 (d, 1H, J = 2.0, Pz5A),
7.68 (d, 1H, J = 2.0, Pz3C), 7.27 (d, 1H, J = 2.0, Pz3A), 6.96 (d, 1H, J
= 7.5, H8), 6.93 (dd, 1H, J = 7.5, 8.4, H6), 6.75 (dd, 1H, J = 7.5, 8.4,
H7), 6.48 (d, 1H, J = 7.6, H5), 6.38 (t, 1H, J = 2.0, Pz4B), 6.37 (t, 1H,
J = 2.0, Pz4C), 6.17 (t, 1H, J = 2.0, Pz4A), 5.66 (s, 1H, H12), 4.05 (d,
1H, J = 6.7, H2), 3.57 (dd, 1H, J = 7.1, 16.0, H1), 3.22 (dd, 1H, J =
10.4, 11.5, H3), 2.73 (d, 1H, J = 16.0, H1′), 2.13 (s, 3H, H15), 2.00
(dd, 1H, J = 1.9, 10.3, H4), 1.75 (s, 3H, H16), 1.36 (d, 9H, J = 8.3,
PMe3). 13C NMR (CDCl3): δ 162.9 (s, C11), 146.0 (s, C9), 144.8 (s,
C14), 144.2 (s, Pz3B), 144.2 (s, Pz3A), 141.8 (s, Pz3C), 138.0 (s,
Pz5C), 137.2 (s, Pz5B), 136.7 (s, Pz5A), 133.1 (s, C10), 129.6 (s, C5),
128.9 (s, C8), 124.6 (s, C6), 123.2 (s, C7), 115.0 (s, C13), 108.3 (s,
C12), 107.3 (s, Pz4B), 107.2 (s, Pz4C), 105.9 (s, Pz4A), 60.1 (s, C3),
54.2 (s, C4), 40.4 (s, C2), 33.1 (s, C1), 13.2 (d, J = 28.1, PMe3), 11.5
(s, C15), 10.1 (s, C16). 31P NMR (CDCl3): δ −9.36 (JP−W = 280 Hz).
CV (DMA): Ep,a = +0.543 V. IR: νNO = 1552 cm−1. HRMS (M+Na)+
obsd (%), calcd (%), ppm: 748.20465 (100), 748.20679 (81.2), −2.9;
749.21042 (95.3), 749.20933 (81.4), 1.5; 750.20893 (95.9), 750.20929
(100), −0.5; 751.2124 (54.6), 751.21319 (47.3), −1.1; 752.21027
(86.6), 752.2125 (82.4), −3.
TpW(NO)(PMe3)(2,3-η2-(4-(1H-pyrrol-2-yl)cyclohex-2-enone))
(13). To a 4-dram vial charged with a stir bar were added 4 (0.050 g,
0.084 mmol) and pyrrole (0.079 g, 1.190 mmol), which were then
dissolved in CHCl3 (1 mL). After 1 min, a 0.17 M DPhAT/EtOH
solution (0.5 mL) was added to the reaction solution, which was
stirred for 3 h. To the reaction solution was added 2 mL of 0.5 M
aqueous NaHCO3, and the two layers were separated. The CHCl3
layer was extracted two times with 1 mL of 0.5 M aqueous NaHCO3,
then dried over anhydrous MgSO4. The organic layer was filtered
through a Celite plug, and the solvent was removed from the filtrate in
vacuo. The residue was dissolved in CHCl3 and added to stirring
hexanes (50 mL). A white precipitate was collected on a 15 mL fine-
porosity fritted disk under vacuum, then rinsed with hexanes (3 × 5
mL), giving 13 (0.043 g, 0.0655 mmol, 78%).
1H NMR (CDCl3): δ 9.21 (s, 1H, NH), 8.16 (d, 1H, J = 2.0, Pz3B),
7.79 (d, 1H, J = 2.0, Pz3A), 7.75 (d, 1H, J = 2.0, Pz5B), 7.68 (d, 1H, J
= 2.0, Pz5C), 7.56 (d, 1H, J = 2.0, Pz5A), 7.38 (d, 1H, J = 2.0, Pz3C),
6.69 (ddd, 1H, J = 1.7, 2.7, 2.7, pyrrole H5′), 6.36 (t, 1H, J = 2.0,
Pz4B), 6.21 (t, 1H, J = 2.0, Pz4A), 6.19 (t, 1H, J = 2.0, Pz4C), 6.09 (q,
1H, J = 2.7, pyrrole H4′), 6.01 (ddd, 1H, J = 1.7, 2.7, 2.7, pyrrole H3′),
4.23 (br m, 1H, H4), 3.34 (ddd, 1H, J = 2.8, 9.7, 12.8, H3), 2.75 (ddd,
1H, J = 6.0, 9.2, 16.2, H6), 2.27 (dddd, 1H, J = 1.2, 5.3, 5.4, 16.2, H6),
2.22 (d, 1H, J = 9.7, H2), 2.18 (dddd, 1H, J = 2.0, 5.4, 6.0, 17.7, H5),
1.65 (ddd, 1H, J = 5.3, 9.2, 17.7, H5), 1.04 (d, 9H, J = 8.6, PMe3). 13
C
NMR (CDCl3): δ 210.9 (s, C1), 143.8 (s, 2C, Pz3A and Pz3B), 140.5
(s, Pz3C), 140.3 (s, C2′), 136.9 (s, Pz5C), 136.6 (s, Pz5B), 136.0 (s,
Pz5A), 117.1 (s, C5′), 107.5 (s, C4′), 107.1 (s, Pz4B), 106.2 (s,
Pz4C), 105.9 (s, Pz4A), 104.9 (s, C3′), 66.4 (d, J = 12.9, C3), 60.1 (s,
C2), 38.0 (s, C4), 35.6 (s, C6), 34.8 (s, C5), 13.7 (d, J = 28.7, PMe3).
31P NMR (CDCl3): δ −8.96 (JP−W = 280 Hz). CV: Ep,a = +0.82 V. IR:
νBH = 2493 cm−1, νCO = 1603 cm−1, νNO = 1563 cm−1. HRMS: [M +
H]+ obsd (%), calcd (%), ppm: 663.19145 (97.2), 663.18871 (84.2),
4.1; 664.19264 (107.2), 664.19125 (80.3), 2.1; 665.19054 (100),
665.19111 (100), −0.9; 666.19417 (34.7), 666.19523 (43.4), −1.6;
667.19559 (94.1), 667.19435 (83.8), 1.9.
TpW(NO)(PMe3)(2,3-η2-(4-(1H-indol-3-yl)cyclohex-2-enone)) (12).
In a 4-dram vial charged with a stir bar, in a fume hood, 4 (0.755 g,
1.265 mmol) was added and dissolved in CHCl3 (2 mL), followed by
the addition of indole (0.527 g, 4.501 mmol). The solution was yellow
and homogeneous. After 1 min, 0.72 mL of a 0.17 M TfOH/MeOH
solution was added to the reaction solution, and the resulting mixture
was stirred for 3 h. To the reaction solution was added 2 mL of 0.5 M
aqueous NaHCO3, and the two layers were separated. The CHCl3
layer was extracted two times with 1 mL of 0.5 M aqueous NaHCO3,
then dried over MgSO4. The organic layer was filtered through a Celite
plug; then the solvent was removed in vacuo. The residue was
dissolved in 1 mL of CHCl3 and added to 50 mL of stirring hexanes to
induce a precipitate. The white precipitate was collected on a 15 mL
fine-porosity fritted disk, then rinsed with hexanes (3 × 5 mL) and
dried in vacuo, giving 12 (0.867 g, 1.214 mmol, 96%).
TpW(NO)(PMe3)(2,3-η2-(4-(5-bromo-1H-indol-3-yl)cyclohex-2-
enone)) (14). To a 4-dram vial charged with a stir bar, in a fume hood
were added 4 (0.050 g, 0.084 mmol) and 5-bromoindole (0.067 g,
0.346 mmol), which were dissolved in CHCl3 (1 mL). After 1 min, a
0.17 M TfOH/MeOH solution (0.05 mL) was added to the reaction
solution, which was stirred for 3 h. To the reaction solution was added
2 mL of 0.5 M aqueous NaHCO3, and the two layers were separated.
The CHCl3 layer was extracted two times with 1 mL of 0.5 M aqueous
NaHCO3, then dried over MgSO4. The organic layer was filtered
through a Celite plug, and solvent was removed from the filtrate in
vacuo. The residue was dissolved in CHCl3 and added to hexanes (50
mL). A white precipitate was collected on a 15 mL fine-porosity fritted
disk under vacuum and then rinsed with hexanes (3 × 5 mL), giving
14 (0.046 g, 0.0579 mmol, 69%).
1H NMR (CDCl3): δ 8.37 (br s, 1H, NH), 8.21 (d, 1H, J = 2.0,
Pz3B), 7.89 (d, 1H, J = 2.0, Pz3A), 7.81 (d, 1H, J = 7.8, Ph4′), 7.77 (d,
1H, J = 2.0, Pz5B), 7.71 (d, 1H, J = 2.0, Pz5C), 7.58 (d, 1H, J = 2.0,
Pz5A), 7.38 (d, 1H, J = 8.0, Ph7′), 7.31 (br s, 1H, indole alkene), 7.30
(d, 1H, J = 2.0, Pz3C), 7.17 (t, 1H, J = 8.0, Ph6′), 7.14 (t, 1H, J = 7.8,
Ph5′), 6.37 (t, 1H, J = 2.0, Pz4B), 6.20 (t, 1H, J = 2.0, Pz4A), 6.18 (t,
1H, J = 2.0, Pz4C), 4.40 (br m, 1H, H4), 3.42 (ddd, 1H, J = 2.2, 10.2,
12.5, H3), 2.61 (dt, 1H, J = 5.8, 17.3, H6), 2.49 (dq, 1H, J = 5.8, 5.8,
7.9, 13.1, H5), 2.31 (d, 1H, J = 10.2, H2), 2.25 (dt, 1H, J = 5.8, 17.3,
H6 overlaps with H2), 2.09 (dq, 1H, J = 5.8, 5.8, 6.5, 13.1, H5), 1.14
(d, 9H, J = 8.4, PMe3). 13C NMR (CDCl3): δ 210.9 (s, C1), 143.8 (s,
Pz3A), 143.7 (s, Pz3B), 140.2 (s, indole alkene C2′), 136.8 (s, Pz5C),
136.8 (s, C7′a), 136.6 (s, Pz5B), 135.8 (s, Pz5A), 126.6 (s, C3′a),
125.7 (s, indole alkene C3′), 122.2 (s, Pz3C), 121.8 (s, C6′), 119.2 (s,
C4′ or C5′), 119.1 (s C4′ or C5′), 111.5 (s, C7′), 107.0 (s, Pz4B),
106.2 (s, Pz4C), 106.0 (s, Pz4CA), 68.0 (d, J = 13.0, C3), 59.7 (s, C2),
1H NMR (CDCl3): δ 8.83 (s, 1H, NH), 8.22 (d, 1H, J = 2.0, Pz3B),
7.92 (d, 1H, J = 2.0, Pz3A), 7.85 (d, 1H, J = 1.7, Ph4′), 7.78 (d, 1H, J =
2.0, Pz5B), 7.73 (d, 1H, J = 2.0, Pz5C), 7.59 (d, 1H, J = 2.0, Pz5A),
7.33 (d, 1H, J = 2.0, Pz3C), 7.31 (d, 1H, J = 2.2, indole alkene H2′),
7.22 (dd, 1H, J = 1.7, 8.5, Ph), 7.15 (d, 1H, J = 8.5, Ph), 6.38 (t, 1H, J
= 2.0, Pz4B), 6.20 (t, 1H, J = 2.0, Pz4A), 6.19 (t, 1H, J = 2.0, Pz4C),
4.25 (br m, 1H, H4), 3.31 (ddd, 1H, J = 1.0, 9.7, 11.4, H3), 2.59−2.54
(m, 1H, H5), 2.54−2.49 (m, 1H, H6), 2.34 (d, 1H, J = 9.7, H2), 2.24−
2.17 (m, 1H, H6), 2.04−1.97 (m, 1H, H5), 1.17 (d, 9H, J = 8.4,
PMe3). 13C NMR (CDCl3): δ 211.0 (s, C1), 143.9 (s, Pz3A), 143.7 (s,
Pz3B), 140.3 (s, Pz3C), 137.0 (s, Pz5C), 136.6 (s, Pz5B), 135.8 (s,
Pz5A), 135.4 (s, C7′a), 128.4 (s, C3a′), 125.5 (s, indole alkene C3′),
123.8 (s, indole alkene C2′), 121.4 (s, C4′), 113.0 (s, Ph), 112.6 (s,
Ph), 112.4 (s, C5′), 107.1 (s, Pz4B), 106.3 (s, Pz4A or Pz4C), 106.0
697
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(s, Pz4A or Pz4C), 68.1 (d, J = 13.5, C3), 59.7 (s, C2), 35.3 (d, J = 2.8,
C4), 33.6 (s, C6), 29.0 (s, C5), 13.8 (d, J = 28.9, PMe3). 31P NMR
C2), 42.1 (s, NMe’B), 40.9 (s, NMe’A), 37.2 (s, C4), 33.8 (s, C5),
27.2 (s, C6), 14.1 (d, J = 30, PMe3). 31P NMR (CD3CN): δ −8.06
(CDCl3): δ −8.34 (JP−W = 281 Hz). CV: Ep,a = +0.89 V. IR: νBH
=
(JP−W = 283 Hz). CV: Ep,a = +1.29 V. IR: νBH = 2507 cm−1, νNO
+
2492 cm−1, νCO = 1593 cm−1, νNO = 1562 cm−1. HRMS: [M + H]+
obsd (%), calcd (%), diff. in ppm: 791.11305 (49.3), 791.11491 (45.8),
2.4; 792.11759 (48), 792.11712 (54.2), 0.6; 793.11539 (100),
793.11539 (100), 0; 794.11609 (75.5), 794.11759 (69.5), 1.9;
795.11838 (113), 795.11776 (100.1), 0.8. [M + Na]+ obsd (%),
calcd (%), ppm: 791.11305 (43.6), 791.11491 (45.8), −2.4; 792.11759
(42.4), 792.11712 (54.2), 0.6; 793.11539 (88.5), 793.11539 (99.9), 0;
794.11609 (66.8), 794.11759 (69.4), −1.9; 795.11838 (100),
795.11776 (100), 0.8. 796.12048 (32.6), 796.12064 (38.4), −0.2;
797.11798 (44.2), 797.11889 (46.9), −1.1.
νIminium = 1574 cm−1. HRMS: (M+) obsd (%), calcd (%), ppm:
690.2359 (82.6), 690.23602 (83.1), −0.2; 691.23784 (69.4),
691.23853 (80.9), −1; 692.23749 (100), 692.23844 (100), −1.4;
693.24245 (43.6), 693.24243 (44.9), 0; 694.24083 (79.4), 694.24168
(83.1), −1.2.
[TpW(NO)(PMe3)N-methyl-N-(4-(5-methylfuran-2-yl)cyclohex-2-
en-1-ylidene)methanaminium](OTf) (19). In a 4-dram vial charged
with a stir bar was added 2-methylfuran (1 mL, 13.38 mmol), which
was then mixed with MeCN (∼0.2 mL). The resulting solution was
treated with a solution of Triflic acid (TfOH) in DCM (10 mL, 0.0034
M) and allowed to stir for 1 min. To this mixture was added 7 (0.1200
g, 0.155 mmol), giving a red and homogeneous solution. After 1 h, the
reaction was quenched outside of the glovebox by the addition of 25
mL of a saturated aqueous NaHCO3 solution. The reaction mixture
was extracted with DCM (3 × 30 mL). The combined organic layers
were dried over MgSO4, filtered through a Celite plug, and
concentrated in vacuo. The residue was redissolved in DCM (4 mL),
and Et2O (100 mL) was added slowly to induce precipitation of an off-
white solid. The solid was collected on a 15 mL fine-porosity fritted
funnel, giving 19 (0.0965 g, 0.113 mmol, 73%).
TpW(NO)(PMe3)(2,3-η2-(4-(1-methyl-1H-indol-3-yl)cyclohex-2-
enone)) (15). To a 4-dram vial charged with a stir bar, in a fume hood
were added 4 (0.050 g, 0.084 mmol) and N-methylindole (0.054 g,
0.417 mmol), which were then dissolved in CHCl3 (1 mL). After 1
min, a 0.17 M TfOH/MeOH solution (0.05 mL) was added to the
reaction solution and stirred for 3 h. To the reaction solution was
added 2 mL of 0.5 M aqueous NaHCO3, and the two layers were
separated. The CHCl3 layer was extracted two times with 1 mL of 0.5
M aqueous NaHCO3, then dried over MgSO4. The organic layer was
filtered through a Celite plug; then the solvent was removed in vacuo.
The residue was dissolved in CHCl3 (1 mL) and added to a stirring
solution of hexanes (50 mL). A white precipitate was collected on a 15
mL fine-porosity fritted funnel under vacuum and then rinsed with
hexanes (3 × 5 mL), giving 15 (0.045 g, 0.0613 mmol, 73%).
1H NMR (CDCl3): δ 8.22 (d, 1H, J = 2.0, Pz3B), 7.90 (d, 1H, J =
2.0, Pz3A), 7.79 (d, 1H, J = 7.9, Ph4′), 7.77 (d, 1H, J = 2.0, Pz5B),
7.71 (d, 1H, J = 2.0, Pz5C), 7.58 (d, 1H, J = 2.0, Pz5A), 7.36 (d, 1H, J
= 2.0, Pz3C), 7.34 (d, 1H, J = 8.2, Ph7′ overlaps with Pz3C), 7.27 (m,
1H, Ph6′ overlaps with chloroform), 7.19 (s, 1H, indole alkene H2′),
7.14 (t, 1H, J = 7.0, Ph5′), 6.37 (t, 1H, J = 2.0, Pz4B), 6.20 (t, 1H, J =
2.0, Pz4A), 6.19 (t, 1H, J = 2.0, Pz4C), 4.51 (br m, 1H, H4), 3.78 (s,
3H, NMe), 3.38 (ddd, 1H, J = 1.2, 9.8, 11.6, H3), 2.60−2.55 (m, 1H,
H6), 2.55−2.49 (m, 1H, H5), 2.31 (d, 1H, J = 9.8, H2), 2.30−2.22 (m,
1H, H6), 2.08−2.01 (m, 1H, H5), 1.17 (d, 9H, J = 8.4, PMe3). 13C
NMR (CDCl3): δ 210.6 (s, C1), 143.7 (s, Pz3A), 143.7 (s, Pz3B),
140.3 (s, Pz3C), 137.4 (s, C7′a or C3a′), 136.8 (s, Pz5C), 136.5 (s,
Pz5B), 135.7 (s, Pz5A), 127.1 (s, C7′a or C3a′), 127.0 (s, indole
alkene C2′), 124.7 (s, indole alkene C3′), 121.6 (s, C6′), 119.2 (s,
C4′), 118.7 (s, C5′), 109.5 (s, C7′), 107.0 (s, Pz4B), 106.1 (s, Pz4A or
Pz4C), 106.0 (s, Pz4A or Pz4C), 68.2 (d, J = 13.1, C3), 59.7 (s, C2),
35.4 (d, J = 2.8 C4), 33.9 (s, C6), 32.8 (s, NMe), 29.8 (s, C5), 13.8 (d,
J = 28.8, PMe3). 31P NMR (CDCl3): δ −7.86 (JP−W = 283 Hz). CV:
Ep,a = +1.00 V. IR: νBH = 2492 cm−1, νCO = 1612 cm−1, νNO = 1562
cm−1. HRMS: [M + H]+ obsd (%), calcd (%), ppm: 727.21835 (89.6),
727.22008 (81.5), −2.4; 728.22153 (72.6), 728.2226 (81.3), −1.5;
729.22211 (100), 729.22256 (100), −0.6; 730.22491 (45.5),
730.22646 (46.8), −2.1; 731.22543 (73.3), 731.22577 (82.5), −0.5.
[TpW(NO)(PMe3)(2,3-η2-N-(4-(1H-pyrrol-2-yl)cyclohex-2-enyli-
dene)-N-methylmethanaminium)](OTf) (18). In a 4-dram vial, 7
(0.055 g, 0.071 mmol) and DPhAT (0.002 g, 0.0062 mmol) were
dissolved in a solution of pyrrole (0.042 g, 0.62 mmol) in CH3CN
(0.304 g), forming a homogeneous tan solution. The solution was
allowed to react for 2 h. The reaction mixture was added to 50 mL of
stirring Et2O to precipitate a light brown solid. The solid was dried in
1H NMR (CDCl3): δ 8.01 (d, J = 2.0, 1H, Pz3B), 7.89 (d, J = 2.0,
1H, Pz5C), 7.80 (d, J = 2.0, 1H, Pz5A or Pz5B), 7.79 (d, J = 2.0, 1H,
Pz5A or Pz5B), 7.53 (d, 1H, J = 2.0, Pz3C), 7.12 (d, 1H, J = 2.0,
Pz3A), 6.45 (t, J = 2.0, 1H, Pz4C), 6.37 (t, J = 2.0, 2H, Pz4A and
Pz4B), 6.12 (d, 1H, J = 2.91, H5′), 5.95 (dd, J = 1.0, 2.91, 1H, H6′),
4.13 (m, 1H, H4), 3.6 (m, 1H, H3), 3.55 (s, 3H, NMe’B), 2.70 (m,
2H, H6), 2.35 (s, 3H, NMe’A), 2.30 (d, J = 1.0, 3H, Me-7′), 2.34
(buried, 1H, H5), 2.31 (buried, 1H, H2), 2.02 (m, 1H, H5), 1.21 (d, J
= 8.93, 9H, PMe3). 13C NMR (CDCl3): δ 186.18 (s, C1), 159.64 (s,
C4′), 151.16 (s, C7′), 144.43 (s, Pz3B), 143.44 (s, Pz3A), 140.94 (s,
Pz3C), 138.33 (s, Pz5C), 138.27 (s, Pz5A or Pz5B), 138.07 (s, Pz5A
or Pz5B), 108.02 (s, Pz4C), 107.82 (s, Pz4A or Pz4B), 107.52 (s, Pz4A
or Pz4B), 106.68 (s, C6′), 106.32 (s, C5′), 68.08 (s, C3), 54.93 (s,
C2), 42.49 (s, NMe’B), 41.18 (s, NMe’A), 37.01 (s, C4), 28.54 (s,
C5), 26.63 (s, C6), 13.94 (s, Me-7′). 31P NMR (CDCl3): δ −9.23
(JP−W = 281 Hz). CV (DMA): Ep,a = +1.20 V. IR: νBH = 2507 cm−1,
νNO + νIminium = 1568 cm−1. HRMS (M+) obsd (%), calcd (%), ppm:
705.23488 (56.7), 705.2357 (82.6), −1.2; 706.23708 (63), 706.23823
(80.9), −1.6; 707.23777 (100), 707.23815 (100), −0.5; 708.24074
(35.6), 708.24214 (45.5), −2; 709.24001 (75.6), 709.24137 (83),
−1.9.
[TpW(NO)(PMe3)N-(2′,4′-dimethoxy-2,3-dihydro-[1,1′-biphenyl]-
4(1H)-ylidene)-N-methylmethanaminium](OTf) (20). In a 4-dram
vial charged with a stir bar was added 1,3-dimethoxybenzene (1.5 mL,
10.29 mmol). To this were added a TfOH/DCM solution (10 mL,
0.0005 M) and MeCN (0.20 mL). The mixture was stirred for 1 min.
To this mixture was added 7 (0.3257 g, 0.42 mmol). After 1 h, the
reaction was quenched outside of the glovebox by the addition of 25
mL of a saturated aqueous NaHCO3 solution. The reaction was
extracted with DCM (3 × 25 mL), and the combined organic layers
were dried over anhydrous MgSO4, filtered through a Celite plug, and
concentrated in vacuo. The yellow residue was redissolved in MeCN (5
mL), and Et2O (150 mL) was slowly added to induce the precipitation
of an off-white solid. The solid was collected on a 15 mL fine-porosity
fritted funnel, giving 20 (0.2795 g, 0.3066 mmol, 73%).
1
vacuo to give 18 (0.031 g, 0.0369 mmol, 52%). H NMR (CDCl3): δ
10.32 (s, 1H, N-H), 8.02 (d, 1H, J = 2.2, Tp), 7.82 (d, 1H, J = 2.2,
Tp), 7.79 (d, 1H, J = 2.2, Tp), 7.77 (d, 1H, J = 2.2, Tp), 7.74 (d, 1H, J
= 2.2, Tp), 7.05 (d, 1H, J = 2.2, Tp), 6.86 (dd, 1H, J = 2.6, 4.2, H5′),
6.4 (t, 1H, J = 2.2, Tp), 6.37 (t, 1H, J = 2.2, Tp), 6.31 (t, 1H, J = 2.2,
Tp), 6.03 (dd, 1H, J = 2.8, 5.5, pyr-β), 5.95 (dd, 1H, J = 2.8, 4.8, pyr-
β), 4.43 (m, 1H, H4), 3.97 (ddd, 1H, J = 3.3, 8.9, 15.0, H3), 3.46 (s,
3H, NMe’B), 2.76 (m, 2H, H6), 2.58 (d, 1H, J = 8.9, H2), 2.32 (s, 3H,
NMe’A), 2.19 (buried, 1H, H5b), 2.08 (m, 1H, H5a), 1.06 (d, 9H, J =
8.9, PMe3). 13C NMR (CDCl3): δ 186.8 (s, C1), 144.2 (s, Tp), 143.1
(s, Tp), 142.4 (s, Tp), 137.7 (s, Tp), 137.6 (s, Tp), 137.5 (s, Tp),
137.4 (s, C2′), 118.7 (s, C5′), 107.8 (s, Tp), 107.0 (s, Tp), 106.4 (s,
pyr-β), 106.4 (s, Tp), 105.4 (s, pyr-β), 69.6 (d, J = 14, C3), 56.9 (s,
1H NMR (CDCl3): δ 8.03 (d, J = 2.0, 1H, Pz3B), 7.85 (d, J = 2.0,
1H, Pz5C), 7.78 (t, J = 2.0, 2H, Pz5A and Pz5B), 7.55−7.52 (m, 2H,
Pz3C and H6′), 7.12 (d, 1H, J = 2.0, Pz3A), 6.66 (dd, J = 2.4, 9.0, 1H,
H5′), 6.48 (d, J = 2.4, 1H, H3′), 6.43 (t, J = 2.0, 1H, Pz4C), 6.37 (m,
2H, Pz4B and Pz4A), 4.75 (m, 1H, H1), 3.85 (s, 3H, H2′OMe or
H4′OMe), 3.84 (s, 3H, H4′OMe or H2′OMe), 3.65 (m, 1H, H6),
3.54 (3H, s, NMe’B), 2.79 (m, 2H, H3), 2.47 (d, J = 9.38, 1H, H5),
2.39 (3H, s, NMe’A), 2.25 (m, 1H, H2), 1.75 (m, 1H, H2), 1.10 (d, J
= 8.95, 9H, PMe3). 13C NMR (CDCl3): δ 185.94 (s, C4), 159.54 (s,
C2′ or C4′), 157.08 (s, C2′ or C4′), 144.15 (s, Pz3B), 143.42 (s,
Pz3A), 140.98 (s, Pz3C), 138.08 (s, Pz5A), 137.88 (s, Pz5C), 137.73
(s, Pz5B), 129.61 (s, C1′), 129.21 (s, C6′), 107.90 (s, Pz4C), 107.51
698
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Organometallics
Article
(s, Pz4B), 107.07 (s, Pz4A), 105.37 (s, C5′), 98.77 (s, C3′), 71.23 (d, J
= 13.5, C6), 56.49 (s, C5), 55.60 (s, H2′OMe or H4′OMe), 55.54 (s,
H2′OMe or H4′OMe), 42.31 (s, NMe’B), 41.01 (s, NMe’A), 34.61 (s,
C1), 32.65 (s, C2), 26.88 (s, C3), 14.16 (d, J = 30.2, PMe3). 31P NMR
(CDCl3): δ −8.55 (JP−W = 286 Hz). CV (DMA): Ep,a = 1.20 V. IR: νBH
= 2503 cm−1, νNO + νIminium = 1567 cm−1. HRMS (M+) obsd (%),
calcd (%), ppm: 761.26172 (100), 761.26196 (80.8), −0.3; 762.2634
(90.7), 762.26448 (81.3), −1.4; 763.26412 (100), 763.26446 (100),
−0.4; 764.26713 (56.5), 764.26831 (47.6), −1.5; 765.268 (98.8),
765.26767 (82.4), 0.4.
Pz4C), 6.14 (t, 1H, J = 2.0, Pz4A), 5.16 (dddd, 1H, J = 4.0, 4.0, 6.0,
50.1, H5), 4.63 (dddd, 1H, J = 0.9, 2.5, 4.0, 23.9, H4), 3.29 (dddd, 1H,
J = 2.5, 3.1, 9.5, 12.0, H3), 2.93 (ddd, 1H, J = 4.0, 16.3, 28.2, H6), 2.43
(dddd, 1H, J = 0.9, 6.0, 14.9, 16.3, H6), 2.11 (d, 1H, J = 9.5, H2), 0.98
(d, 9H, J = 8.6, PMe3). 13C NMR (d6-DMSO): δ 205.0 (s, C1), 143.2
(s, Pz3B), 142.4 (s, Pz3A), 139.9 (s, Pz3C), 136.6 (s, Pz5C), 136.3 (s,
Pz5B), 136.0 (s, C7′a), 135.4 (s, Pz5A), 127.0 (s, C3′a), 123.3 (s,
indole alkene C2′), 120.6 (s, C6′), 118.6 (s, C4′), 118.1 (s C5′), 118.0
(d, J = 3.3, C3′), 111.0 (s, C7′), 106.6 (s, Pz4B), 105.9 (s, Pz4C),
105.0 (s, Pz4CA), 93.3 (d, J = 172.3, C5), 62.1 (dd, J = 5.6, 12.8, C3),
58.1 (s, C2), 41.3 (d, J = 22.0, C6), 39.5 (s, overlaps with d6-DMSO,
[TpW(NO)(PMe3)N-methyl-N-(2′,4′,6′-trimethoxy-2,3-dihydro-
[1,1′-biphenyl]-4(1H)-ylidene)methanaminium](OTf) (21). In a 4-
dram vial charged with a stir bar was added 1,3,5-trimethoxybenzene
(1.021 g, 6.064 mmol), which was then dissolved in MeCN (∼0.2 mL)
treated with a solution of TfOH in DCM (10 mL, 0.0034 M) and
allowed to stir for 1 min. To this mixture was added 7 (0.2011 g, 0.26
mmol). The mixture appeared red and homogeneous. After stirring for
1 h, the reaction was quenched outside of the glovebox by the addition
of 30 mL of saturated aqueous NaHCO3 solution. The reaction
mixture was extracted with DCM (3 × 30 mL). The organic layers
were combined and dried over anhydrous MgSO4, filtered through a
Celite plug, and concentrated in vacuo. The residue was redissolved in
MeCN (6 mL), and Et2O (150 mL) was added slowly to induce
precipitation of a white solid. The solid was collected on a 15 mL fine-
porosity fritted funnel, giving 21 (0.1521 g, 3.759 mmol, 62%).
1H NMR (CDCl3): δ 8.03 (d, J = 2.0, 1H, Pz3B), 7.86 (d, J = 2.0,
1H, Pz5C), 7.78 (d, J = 2.0, 1H Pz5A), 7.77 (d, J = 2.0, 1H, Pz5B),
7.38 (d, J = 2.0, 1H, Pz3C), 7.02 (d, J = 2.0, 1H, Pz3A), 6.44 (t, J = 2.0,
1H, Pz4C), 6.37 (t, J = 2.0, 2H, Pz4B and Pz4A), 6.21 (s, 2H, H5′ and
H3′), 5.02 (ddd, 1H, J = 2.55, 6.15, 10.06, H1) 3.86 (s, 6H, H2′OMe
and H6′OMe), 3.84 (s, 3H, H4′OMe), 3.84 (buried, 1H, H6), 3.57 (s,
3H, NMe’B), 2.85 (m, 2H, H3), 2.32 (s, 3H, NMe’A), 2.31 (buried,
1H, H5), 2.06 (m, 1H, H2), 1.97 (m, 1H, H2), 1.07 (d, J = 9.06, 9H,
PMe3). 13C NMR (CDCl3): δ 185.5 (s, iminium), 160.2 (s, C2′, C4′,
and C6′), 144.2 (s, Pz3B), 143.5 (s, Pz3A), 140.4 (s, Pz3C), 138.2 (s,
Pz5A), 137.8 (s, Pz5C), 137.8 (s, Pz5B), 116.20 (s, C1′), 108.0 (s,
Pz4C), 107.5 (s, Pz4B or Pz4A), 107.0 (s, Pz4B or Pz4A), 91.3 (s, C3′
and C5′), 72 (d, J = 13.43, C6), 57.0 (s, C5), 55.9 (s, H2′OMe and
H4′OMe or H6′OMe), 55.5 (s, H2′OMe and H4′OMe or H6′OMe),
42.3 (s, NMe’B), 40.8 (s, NMe’A), 32.0 (s, C1), 30.5 (s, C2) 27.4 (s,
C4), 12.9 (d, J = 29.0, PMe3). 31P NMR (CDCl3): δ −8.88 (JP−W
=
280 Hz). CV: Ep,a = +0.93 V. IR: νBH = 2496 cm−1, νCO = 1598 cm−1,
νNO = 1567 cm−1. HRMS: [M + H]+ obsd (%), calcd (%), diff. in ppm:
731.19283 (84.1), 731.19499 (82.1), 3; 732.19579 (69.2), 732.19752
(81.1), 2.4; 733.19704 (100), 733.19746 (100), 0.6; 734.19874 (51.2),
734.2014 (46.1), 3.6; 735.20095 (91.1), 735.20067 (82.8), 0.4. [M +
Na]+ obsd (%), calcd (%), ppm: 731.19251 (68.8), 731.19499 (82.1),
−3.4; 732.19627 (96), 732.19752 (81.1), −1.7; 733.19898 (100),
733.19746 (100), 2.1; 734.19747 (53.5), 734.2014 (46.1), −5.4;
735.19886 (93.3), 735.20067 (82.8), −2.5.
TpW(NO)(PMe3)(2,3-η2-(5-fluoro-4-(1H-pyrrol-2-yl)cyclohex-2-
enone)) (23). In a NMR tube, in a fume hood, 4 (0.053 g, 0.089
mmol) was added and dissolved in 0.5 mL of DCM, giving a solution
that was yellow and homogeneous. To this was added Selectfluor
(0.039 g, 0.111 mmol) dissolved in 1 mL of acetonitrile; then Na2CO3
(0.031 g, 0.294 mmol) was added, resulting in a heterogeneous
solution. The solution was stirred for 1 min; then pyrrole (0.244 g,
3.636 mmol) was added to the reaction solution, and the mixture
stirred for 4 h. To the reaction solution was added 2 mL of saturated
aqueous NaHCO3, and the two layers were separated. The DCM layer
was extracted two times with 1 mL of saturated aqueous NaHCO3,
then dried over MgSO4. The organic layer was filtered through a Celite
plug; then the solvent was removed in vacuo. The residue was
dissolved in 1 mL of CHCl3 and added to 50 mL of stirring hexanes,
which resulted in a yellow precipitate. The precipitate was collected on
a 15 mL fine-porosity fritted disk under vacuum, then rinsed with
hexanes (3 × 5 mL) and dried in vacuo. Yellow precipitate 23 was
collected (0.034 g, 0.050 mmol, 56.1% yield).
1H NMR (CDCl3): δ 9.11 (s, 1H, NH), 8.13 (d, 1H, J = 2.0, Pz3B),
7.75 (d, 1H, J = 2.0, Pz5B), 7.71 (d, 1H, J = 2.0, Pz3A), 7.69 (d, 1H, J
= 2.0, Pz5C), 7.56 (d, 1H, J = 2.0, Pz5A), 7.34 (d, 1H, J = 2.0, Pz3C),
6.79 (ddd, 1H, J = 1.7, 2.3, 2.3, pyrrole H5′), 6.36 (t, 1H, J = 2.0,
Pz4B), 6.20 (t, 1H, J = 2.0, Pz4C), 6.16 (t, 1H, J = 2.0, Pz4A), 6.12 (m,
2H, pyrrole H4′ and H3′), 5.09 (dddd, 1H, J = 3.0, 3.0, 5.3, 50.4, H5),
4.47 (ddd, 1H, J = 2.7, 3.0, 35.0, H4), 3.20 (dddd, 1H, J = 1.5, 2.7, 9.4,
12.6, H3), 3.05 (ddd, 1H, J = 3.0, 16.4, 35.0, H6), 2.62 (dddd, 1H, J =
1.5, 5.3, 12.6, 16.4, H6), 2.28 (d, 1H, J = 9.4, H2), 0.98 (d, 9H, J = 8.6,
PMe3). 13C NMR (CDCl3): δ 206.5 (d, J = 4.5, C1), 143.9 (d, J = 1.9,
Pz3B), 143.6 (s, Pz3A), 140.4 (s, Pz3C), 136.9 (s, Pz5C), 136.7 (s,
Pz5B), 136.1 (s, Pz5A), 134.9 (d, J = 2.1, C2′), 118.0 (s, C5′), 107.4
(s, C3′ or C4′), 107.2 (s, C3′/C4′ or Pz4B), 107.2 (s, C3′/C4′ or
Pz4B), 106.4 (s, Pz4C), 105.9 (s, Pz4A), 96.2 (d, J = 172.5, C5), 60.6
(dd, J = 4.0, 13.2, C3), 59.1 (s, C2), 42.3 (dd, J = 2.4, 18.2, C4), 42.2
(d, J = 22.4, C6), 13.6 (d, J = 29.0, PMe3). 31P NMR (CDCl3): δ
−9.68 (JP−W = 275 Hz). CV: Ep,a = +0.93 V. IR: νBH = 2493 cm−1, νCO
= 1614 cm−1, νNO = 1557 cm−1. HRMS: [M + H]+ obsd (%), calcd
(%), ppm: 681.17903 (86.8), 681.17929 (84.2), −0.4; 682.18077
(82.5), 682.18183 (80.3), −1.6; 683.18074 (100), 683.18169 (100),
−1.4; 684.1834 (45.7), 684.18581 (43.3), −3.5; 685.18549 (80.7),
685.18493 (83.8), 0.8.
C3), 14.1 (d, J = 30.0, PMe3). 31P NMR (CDCl3): δ −8.32 (JP−W
290 Hz). CV (DMA): Ep,a = 1.13 V. νBH = 2506 cm−1, νNO + νIminium
=
=
1568 cm−1. HRMS (M+) obsd (%), calcd (%), ppm: 791.27138 (95),
791.27254 (80.1), −1.5; 792.27477 (82.1), 792.27506 (81.4), −0.4;
793.2743 (92.1), 793.27506 (100), −1; 794.27958 (54.4), 794.27887
(48.4), 0.9; 795.2786 (100), 795.27826 (82.2), 0.4.
TpW(NO)(PMe3)(2,3-η2-(5-fluoro-4-(1H-indol-3-yl)cyclohex-2-
enone)) (22). In a NMR tube, in a fume hood, 4 (0.021 g, 0.036
mmol) was added and dissolved in 0.5 mL of DCM, giving a solution
that was yellow and homogeneous. To this solution was added
Selectfluor (0.018 g, 0.050 mmol) dissolved in CH3CN (1 mL); then
Na2CO3 (0.011 g, 0.107 mmol) was added, resulting in a
heterogeneous solution. The solutions were combined and stirred
for 1 min; then indole (0.020 g, 0.175 mmol) was added to the
reaction solution, and it was stirred for 17 h. To the reaction solution
was added 2 mL of saturated aqueous NaHCO3, and the two layers
were separated. The DCM layer was extracted two times with 1 mL of
saturated aqueous NaHCO3, then dried over MgSO4. The organic
layer was filtered through a Celite plug,; then the solvent was removed
in vacuo. The residue was dissolved in 1 mL of CHCl3 and added to 50
mL of stirring hexanes, which resulted in a yellow precipitate. The
precipitate was collected on a 15 mL fine-porosity fritted disk under
vacuum, then rinsed with hexanes (3 × 5 mL) and dried in vacuo,
giving 22 (0.020 g, 0.0277 mmol, 77%).
TpW(NO)(PMe3)(2,3-η2-(5-chloro-4-(1H-pyrrol-2-yl)cyclohex-2-
enone)) (24). In a 4-dram vial with a stir bar, in a fume hood, 4 (0.074
g, 0.124 mmol) was added and dissolved in 0.5 mL of DCM. The
yellow, homogeneous solution was placed in an ice bath. N-
Chlorosuccinimide (0.005 g, 0.039 mmol) was dissolved in 0.25 mL
of DCM, then placed in the ice bath. The two solutions were
combined and stirred, still cold, for 30 s, resulting in the reaction
solution turning a dark yellow color. After 30 s, pyrrole (0.017 g, 0.255
mmol) was added to the reaction solution and stirred, still cold, for 4.5
1H NMR (d6-DMSO): δ 10.56 (br s, 1H, NH), 8.11 (d, 1H, J = 2.0,
Pz3B), 7.83 (d, 1H, J = 2.0, Pz5B), 7.78 (d, 1H, J = 2.0, Pz5C), 7.70
(d, 1H, J = 2.0, Pz3A), 7.67 (d, 1H, J = 7.8, Ph4′), 7.63 (d, 1H, J = 2.0,
Pz5A), 7.37 (d, 1H, J = 2.0, Pz3C), 7.36 (d, 1H, J = 2.3, indole alkene
H2′), 7.34 (d, 1H, J = 7.8, Ph7′), 7.05 (t, 1H, J = 7.8, Ph6′), 6.98 (t,
1H, J = 7.8, Ph5′), 6.38 (t, 1H, J = 2.0, Pz4B), 6.22 (t, 1H, J = 2.0,
699
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h. To the reaction solution was added 2 mL of saturated aqueous
Na2CO3, and the two layers were separated. The DCM layer was
extracted two times with 1 mL of saturated aqueous Na2CO3, then
dried over MgSO4. The organic layer was filtered through a Celite
plug; then the solvent was removed in vacuo. The residue was
dissolved in 1 mL of CHCl3 and added to 50 mL of hexanes, which
resulted in a precipitate. The precipitate was collected on a 15 mL fine-
porosity fritted disk under vacuum, then rinsed with Et2O (3 × 5 mL)
and dried in vacuo. An off-white precipitate, 24, was collected (0.060 g,
0.0868 mmol, 70%).
obsd (%), calcd (%), ppm: 769.14892 (64.4), 769.14738 (65.1), 2.0;
770.14914 (69.3), 770.14973 (68.5), −0.8; 771.14728 (100),
771.14873 (100), −1.9; 772.14971 (57.6), 772.15133 (57.1), −2.1;
773.15087 (94.8), 773.15135 (90.9), −0.6.
TpW(NO)(PMe3)(2,3-η2-(5-hydroxy-4-(1H-indol-3-yl)cyclohex-2-
enone)) (27). In a NMR tube, in a fume hood, 26 (0.014 g, 0.021
mmol) was added and dissolved in 0.5 mL of CHCl3, followed by the
addition of indole (0.028 g, 0.246 mmol). The solution was yellow and
homogeneous. After 1 min, 0.02 mL of a 0.17 M TfOH/EtOH
solution was added to the reaction solution, and the mixture was
stirred for 48 h. The solution became heterogeneous, and the resulting
solid was collected on a 15 mL fine-porosity fritted disk under vacuum,
then rinsed with 5 mL of hexane and dried in vacuo. A yellow
precipitate was obtained (0.009 g, 0.0126 mmol, 60%).
1H NMR (CDCl3): δ 8.81 (br s, 1H, NH), 8.34 (d, 1H, J = 2.0,
Pz3B), 7.77 (d, 1H, J = 2.0, Pz3A overlaps with Pz5B), 7.76 (d, 1H, J =
2.0, Pz5B overlaps with Pz3A), 7.71 (d, 1H, J = 2.0, Pz5C), 7.58 (d,
1H, J = 2.0, Pz5A), 7.35 (d, 1H, J = 2.0, Pz3C), 6.81 (ddd, 1H, J = 1.6,
2.6, 2.6, pyrrole H5′), 6.37 (t, 1H, J = 2.0, Pz4B), 6.23 (ddd, 1H, J =
1.6, 2.6, 2.6, pyrrole H3′), 6.21 (t, 1H, J = 2.0, Pz4C), 6.18 (m, 1H,
pyrrole H4′ overlaps with Pz4A), 6.18 (t, 1H, J = 2.0, Pz4A overlaps
with pyrrole H4′), 4.81 (ddd, 1H, J = 3.6, 4.0, 6.5, H5), 4.54 (br s, 1H,
H4), 3.17 (m, 1H, H3 overlaps with H6), 3.15 (dd, 1H, J = 4.0, 16.4,
H6 overlaps with H3), 2.64 (ddd, 1H, J = 1.2, 6.5, 16.4, H6), 2.22 (d,
1H, J = 9.4, H2), 1.00 (d, 9H, J = 8.6, PMe3). 13C NMR (CDCl3): δ
205.6 (s, C1), 143.9 (s, Pz3A or Pz3B), 143.8 (s, Pz3A or Pz3B), 140.4
(s, Pz3C), 137.0 (s, Pz5C), 136.8 (s, Pz5B), 136.0 (s, Pz5A), 135.0 (s,
C2′), 117.6 (s, C5′), 108.3 (s, C3′), 108.0 (s, C4′), 107.2 (s, Pz4B),
106.4 (s, Pz4C), 106.0 (s, Pz4A), 65.3 (s, C5), 62.2 (d, J = 13.2, C3),
57.9 (s, C2), 45.3 (s, C6), 44.6 (d, J = 2.4, C4), 13.6 (d, J = 29.0,
1H NMR (d6-DMSO): δ 10.88 (br s, 1H, NH), 8.19 (d, 1H, J = 2.0,
Pz3B), 8.09 (d, 1H, J = 2.0, Pz5B), 8.06 (d, 1H, J = 2.0, Pz5C), 7.88
(d, 1H, J = 2.0, Pz3A), 7.76 (d, 1H, J = 2.0, Pz5A), 7.68 (d, 1H, J = 8.0,
Ph4′ or Ph7′), 7.61 (d, 1H, J = 2.0, Pz3C), 7.41 (d, 1H, J = 2.1, indole
alkene H2′), 7.36 (d, 1H, J = 8.0, Ph4′ or Ph7′), 7.06 (t, 1H, J = 8.0,
Ph5′ or Ph6′), 6.98 (t, 1H, J = 8.0, Ph5′ or Ph6′), 6.49 (t, 1H, J = 2.0,
Pz4B), 6.33 (t, 1H, J = 2.0, Pz4C), 6.27 (t, 1H, J = 2.0, Pz4A), 3.93 (s,
1H, OH) 4.49 (br m, 1H, H4), 4.29 (ddd, 1H, J = 4.5, 4.5, 6.8, H5),
3.23 (ddd, 1H, J = 2.5, 9.5, 12.2, H3), 2.65 (dd, 1H, J = 4.5, 16.0, H6),
2.09 (dd, 1H, J = 6.8, 16.0, H6′), 1.91 (d, 1H, J = 9.5, H2), 1.01 (d,
9H, J = 8.8, PMe3). 13C NMR (d6-DMSO): δ 207.4 (s, C1), 143.9 (s,
Pz3B), 142.7 (s, Pz5A), 141.1 (s, Pz3C), 137.4 (s, Pz5C), 136.9 (s,
Pz5B), 136.1 (s, C7′a), 136.1 (s, Pz3A), 127.9 (s, C3′a), 123.8 (s,
indole alkene C2′), 120.5 (s, C5′ or C6′), 119.8 (s, C3′), 118.9 (s, C4′
or C7′), 117.9 (s, C5′ or C6′), 111.2 (s, C4′ or C7′), 107.1 (s, Pz4B),
106.4 (s, Pz4C), 105.3 (s, Pz4A), 69.5 (s, C5), 64.3 (d, J = 13.6, C3),
58.4 (s, C2), 43.8 (s, C6), 41.1 (s, C4), 12.8 (d, J = 28.9, PMe3). 31P
NMR (d6-DMSO): δ −6.45 (JP−W = 283 Hz). CV (DMA/DMSO):
Ep,a = +0.84 V. IR: νBH = 2486 cm−1, νCO = 1600 cm−1, νNO = 1569
cm−1. HRMS: [M + Na]+ obsd (%), calcd (%), ppm: 751.17891
(78.3), 751.18127 (81.9), −3.1; 752.18242 (87.4), 752.1838 (81),
−1.8; 753.18044 (100), 753.18374 (100), −4.4; 754.18811 (37.6),
754.18768 (46.2), 0.6; 755.18565 (79.0), 755.18696 (82.8), −1.7.
[TpW(NO)(PMe3)N-2-fluoro-2′,4′-dimethoxy-2,3-dihydro-[1,1′-bi-
phenyl]-4(1H)-ylidene)-N-methylmethanaminium] ](OTf) (30). In a
4-dram vial charged with a stir bar, 1,3-dimethoxybenzene (0.30 mL,
2.06 mmol) was added. To this were added a TfOH/DCM solution (1
mL, 0.0034 M) and MeCN (0.20 mL). The homogeneous solution
was stirred for 1 min. To this mixture was added 28 (0.0550 g, 0.066
mmol), creating a light brown homogeneous solution. After 1.5 h, the
reaction was quenched, outside of the glovebox, by the addition of 25
mL of saturated aqueous NaHCO3 solution. The reaction was
extracted with DCM (3 × 25 mL), dried over MgSO4, filtered through
a Celite plug, and concentrated in vacuo. The residue was redissolved
in MeCN (3 mL), and Et2O (150 mL) was slowly added to induce the
precipitation of a light brown solid. The solid was collected on a 15
mL fine-porosity fritted funnel, giving 30 (0.0290 g, 0.031 mmol,
47%).
PMe3). 31P NMR (CDCl3): δ −9.77 (JP−W = 277 Hz). CV: Ep,a
=
+1.01 V. IR: νBH = 2493 cm−1, νCO = 1604 cm−1, νNO = 1564 cm−1.
HRMS: [M + H]+ obsd (%), calcd (%), ppm: 681.17903 (86.8),
681.17929 (84.2), −0.4; 682.18077 (82.5), 682.18183 (80.3), −1.6;
683.18074 (100), 683.18169 (100), −1.4; 684.1834 (45.7), 684.18581
(43.3), −3.5; 685.18549 (80.7), 685.18493 (83.8), 0.8.
TpW(NO)(PMe3)(2,3-η2-(5-chloro-4-(1H-indol-3-yl)cyclohex-2-
enone)) (25). In a 4-dram vial charged with a stir bar, in a fume hood,
4 (0.050 g, 0.084 mmol) was added and dissolved in 0.5 mL of CHCl3.
The yellow, homogeneous solution was placed in an ice bath. A
separate solution was prepared of N-chlorosuccinimide (0.015 g, 0.116
mmol) dissolved in MeCN (0.25 mL) and placed in the ice bath. The
solutions were combined and stirred, still cold, for 2 min, resulting in
the reaction solution turning a dark yellow color. After 2 min, indole
(0.048 g, 0.416 mmol) was added to the reaction solution, still cold,
and it was stirred for 25 min. To the reaction solution was added 2 mL
of saturated aqueous Na2CO3, and the two layers were separated. The
CHCl3 layer was extracted two times with 1 mL of saturated aqueous
Na2CO3, then dried over MgSO4. The organic layer was filtered
through a Celite plug; then the solvent was removed in vacuo. The
residue was dissolved in 1 mL of CHCl3 and added to stirring hexanes
(50 mL), which resulted in a precipitate. The precipitate was collected
on a 15 mL fine-porosity fritted funnel under vacuum, washed with
hexanes (3 × 5 mL), and dried in vacuo. An off-white precipitate, 25,
was collected (0.038 g, 0.0512 mmol, 61%).
1H NMR (CDCl3): δ 8.48 (br s, 1H, NH), 8.17 (d, 1H, J = 2.0,
Pz3B), 7.84 (d, 1H, J = 2.0, Pz3A), 7.83 (d, 1H, J = 7.8, Ph4′) 7.77 (d,
1H, J = 2.0, Pz5B), 7.71 (d, 1H, J = 2.0, Pz5C), 7.59 (d, 1H, J = 2.0,
Pz5A), 7.43 (d, 1H, J = 2.3, indole alkene H2′), 7.39 (t, 1H, J = 7.8,
Ph7′), 7.31 (d, 1H, J = 2.0, Pz3C), 7.20 (t, 1H, J = 7.8, Ph6′ overlaps
with Ph5′), 7.16 (t, 1H, J = 7.8, Ph5′ overlaps with Ph6′), 6.37 (t, 1H,
J = 2.0, Pz4B), 6.20 (t, 1H, J = 2.0, Pz4A), 6.17 (t, 1H, J = 2.0, Pz4C),
5.00 (ddd, 1H, J = 4.7, 7.7, 8.6, H5), 4.81 (br m, 1H, H4), 3.31 (ddd,
1H, J = 2.8, 9.6, 12.2, H3), 3.23 (dd, 1H, J = 4.7, 17.0, H6), 2.77 (ddd,
1H, J = 0.9, 7.7, 17.0, H6), 2.30 (d, 1H, J = 9.6, H2), 1.08 (d, 9H, J =
8.5, PMe3). 13C NMR (CDCl3): δ 206.6 (s, C1), 143.9 (s, Pz3A or
Pz3B), 143.9 (s, Pz3A or Pz3B), 140.4 (s, Pz3C), 137.0 (s, Pz5C),
136.7 (s, Pz5B), 136.0 (s, C7′a), 136.0 (s, Pz5A), 128.0 (s, C3′a),
123.7 (s, indole alkene C2′), 122.0 (s, C6′), 120.7 (s, C3′), 119.6 (s,
C5′), 119.4 (s, C4′), 111.5 (s, C7′), 107.2 (s, Pz4B), 106.3 (s, Pz4A or
Pz4C), 106.0 (s, Pz4A or Pz4C), 65.5 (d, J = 15.5, C3), 62.9 (s, C5),
58.1 (s, C2), 44.9 (s, C6), 42.1 (s, C4), 13.9 (d, J = 28.9, PMe3). 31P
NMR (CDCl3): δ −8.90 (JP−W = 280 Hz). CV: Ep,a = +1.07 V. IR: νBH
= 2494 cm−1, νCO = 1602 cm−1, νNO = 1557 cm−1. HRMS: [M + Na]+
1H NMR (300 MHz, CDCl3): δ 7.99 (d, J = 2.0, 1H, Pz3B), 7.87
(d, J = 2.0, 1H, Pz5C), 7.78 (d, J = 2.0, 2H, Pz5B and Pz5B), 7.57 (dd,
J = 2.29, 8.61,1H, H6′), 7.52 (d, J = 2.0, 1H, Pz3C), 7.08 (d, J = 2.0,
1H, Pz3a), 6.64 (dd, J = 2.42, 8.91, 1H, H8′), 6.50 (d, J = 2.42, 1H,
H9′), 6.44 (t, J = 2.0, 1H, Pz4C), 6.40 (t, J = 2.0, 1H, Pz4a), 6.36 (t, J
= 2.0, 1H, Pz4B), 5.07 (m, 1H, H4), 4.87 (m, 1H, H5), 3.83 (s, 6H,
H5′OMe and Hz’OMe), 3.59 (burried, 1H, H3), 3.53 (s, 3H, NMe’B),
3.29 (m, 1H, H6), 3.09 (dd, J = 16.02, 42.14, 1H, H6), 2.49 (d, J =
11.43, 1H, H2), 2.30 (s, 1H, NMe’A), 0.99 (d, J = 9.09, 9H, PMe3).
13C NMR (CDCl3): 181.27 (s, C1), 160.32 (s, C7′), 157.41 (s, C5′),
144.68 (s, Pz3B), 143.63 (s, Pz3A), 140.82 (s, Pz3C), 138.52 (s, Pz5A
or Pz5B orPz5C), 138.25 (s, Pz5A or Pz5B or Pz5C), 138.22 (s, Pz5A
or Pz5B or Pz5C), 131.60 (s, C9′), 122.67 (d, J = 2.96, C4′), 108.11
(s, Pz4C), 107.91 (s, Pz4B), 107.65 (s, Pz4A), 105.56 (s, C8′), 98.48
(s, C6′), 92.22 (d, J = 178.47, C5), 65.84 (d, C3), 57.04 (s, C2), 55.73
(s, C5′OMe/C7′OMe), 42.89 (s, NMeB′), 41.22 (s, NMeA′), 38.62
(d, J = 17.98, C4), 33.42 (d, J = 23.03, C6), 14.39 (d, J = 30.11, PMe3).
31P NMR (CDCl3): δ −9.08 (JP−W = 283 Hz). CV (DMA): Ep,a = 1.27
700
dx.doi.org/10.1021/om3012008 | Organometallics 2013, 32, 691−703

Organometallics
Article
V. IR: νBH = 2514 cm−1, νNO + νIminium = 1571 cm−1. HRMS (M+)
obsd (%), calcd (%), ppm: 779.25124 (80.7), 779.25253 (80.8), −1.7;
780.25368 (74.3), 780.25506 (81.3), −1.8; 781.25432 (100),
781.25504 (100), −0.9; 782.2577 (49.9), 782.25889 (47.6), −1.5;
783.25644 (80.1), 783.25824 (82.4), −2.3.
144.46 (s, Pz3A), 142.1 (s, Pz3C), 138.78 (s, Pz5C or Pz5B or Pz5A),
113.45 (s, C4′), 108.25 (s, Pz4A or Pz4B or Pz4C), 108.11 (s, Pz4A or
Pz4B or Pz4C), 108.10 (s, Pz4A or Pz4B or Pz4C), 92.48 (s, C6′),
91.74 (s, C6′), 67.22 (s, C3), 58.902 (s, C3), 56.75 (s, C5′ OMe),
56.09 (s, C7′OMe or C5′OMe), 55.97 (s, C7′OMe or C5′OMe),
55.74 (s, C2), 42.53 (s, NMe’B), 41.39 (s, NMe’A), 39.13 (s, C4),
38.33 (s, C6), 13.37 (d, J = 30.64, PMe3). 31P NMR (CDCl3): δ −8.41
[TpW(NO)(PMe3)N-(2-fluoro-2′,4′,6′-trimethoxy-2,3-dihydro-
[1,1′-biphenyl]-4(1H)-ylidene)-N-methylmethanaminium](OTf) (31).
In a 4-dram vial charged with a stir bar, 1,3,5-trimethoxybenzene
(0.3056 g, 1.81 mmol) was added. To this were added a TfOH/
CH2Cl2 solution (1 mL, 0.0034 M) and MeCN (0.20 mL), and the
mixture was stirred for 1 min. To this mixture was added 28 (0.1029 g,
0.1248 mmol). After 1.5 h, the reaction was quenched, outside of the
glovebox, by the addition of 25 mL of saturated aqueous NaHCO3.
The reaction mixture was extracted with DCM (3 × 25 mL), dried
over MgSO4, filtered through a Celite plug, and concentrated in vacuo.
The residue was redissolved in MeCN (3 mL), and Et2O (150 mL)
was slowly added to induce the precipitation of an off-white solid. The
solid was collected on a 15 mL fine-porosity fritted funnel, giving 31
(0.0631 g, 0.066 mmol, 53%).
(JP−W = 283 Hz). CV (DMA): Ep,a = 1.30 V. νBH = 2512 cm−1, νNO
+
νIminium = 1566 cm−1. HRMS (M+) obsd (%), calcd (%), ppm:
825.23306 (86.5), 825.23356 (70.2), −0.6; 826.23529 (84.4),
826.23591 (75.9), −0.8; 827.2343 (113.6), 827.23497 (110), −0.8;
828.23614 (54.1), 828.23753 (65.2), −1.7; 829.2377 (100), 829.23757
(100), 0.2. 830.2404 (38.1), 830.24004 (36.8), 0.4; 831.23777 (28.6),
831.23763 (27.4), 0.2.
4-(1H-Indol-3-yl)cyclohex-2-enone (33). In a 4-dram vial charged
with a stir bar, in a fume hood, 12 (0.104 g, 0.145 mmol) was added to
and dissolved in 5 mL of acetone. The solution was colorless and
homogeneous. Finely ground CAN (0.089 g, 0.163 mmol) was added
to the vial, forming a green slurry. After stirring for 25 min, the
reaction solution was added to 200 mL of hexanes, resulting in a
heterogeneous suspension, which gradually formed an oily residue
when allowed to settle. The suspension was filtered on a 60 mL
medium-porosity fritted disk containing a Celite pad. The filtrate was
concentrated in vacuo, leaving a yellow residue. A 0.5 in. silica plug in a
60 mL medium-porosity fritted disk was activated with 2 min of
microwave irradiation. Once the silica plug cooled to room
temperature, Et2O (50 mL) was added to make a slurry; then 1 in.
of sand was added to the top of the slurry. The residue from the filtrate
was dissolved in 100 mL of ether and passed through the silica plug,
then eluted with 350 mL of Et2O. The solvent from the elutant was
removed under vacuum, leaving a yellow residue. That residue was
dissolved in 1 mL of DCM, loaded onto a radial silica chromatotron,
and eluted with a 9:1 hexanes/EtOAc solution to give 33 as a colorless
residue (0.018 g, 0.088 mmol, 61%).
1H NMR (500 MHz, CDCl3): δ 8.0 (d, J = 2.0, 1H, Pz3B), 7.89 (d,
J = 2.0, 1H, Pz5A or Pz5B or Pz5C), 7.79 (d, J = 2.0, 2H, Pz5A or
Pz5B or Pz5C), 7.43 (d, J = 2.0, 1H, Pz3C), 7.09 (d, J = 2.0, 1H,
Pz3A), 6.47 (t, J = 2.0, 1H, Pz4C), 6.41 (t, J = 2.0, 1H, Pz4A or
PZ4B), 6.37 (t, J = 2.0, 1H, Pz4A or Pz4B), 6.25 (d, J = 2.3, 1H, H5′
or H3′), 6.21 (d, J = 2.3, 1H, H5′ or H3′), 5.27 (m, 1H, H1), 5.06 (m,
1H, H2), 4.06 (m, 1H, H6), 3.86 (s, 3H, H2′OMe or H4′OMe or
H6′OMe), 3.85 (s, 3H, H2′OMe or H4′OMe or H6′OMe), 3.84 (s,
3H, H2′OMe or H4′OMe or H6′OMe), 3.60 (s, 3H, NMe’B), 3.15
(m, 2H, H3), 2.45 (d, J = 9.2, 1H, H5), 2.40 (s, 3H, NMe’A), 1.09 (d,
J = 8.88, 9H, PMe3). 13C NMR (CDCl3): δ 183.0 (d, J = 3.04, C4),
161.18 (s, C2′ or C4′ or C6′), 160.76 (s, C2′ or C4′ or C6′), 158.16
(s, C2′ or C4′ or C6′), 144.37 (s, Pz3B), 143.22 (s, Pz3A), 140.27 (s,
Pz3C), 138.27 (s, Pz5A or Pz5B or Pz5C), 138.11 (s, Pz5A or Pz5B or
Pz5C), 137.93 (s, Pz5A or Pz5B or Pz5C), 110.23 (d, J = 3.75, C1′),
108.0 (s, Pz4C), 107.67 (s, Pz4A or Pz4B), 107.38 (s, Pz4A or Pz4B)
92.4 (s, C3′ or C5′), 91.8 (d, J = 152.88, C2), 91.05 (s, C3′ or C5′),
65.66 (d, J = 12.86, C6), 56.24 (s, C5), 55.98 (s, C2′OMe or C4′OMe
or C6′OMe), 55.51 (s, C2′OMe or C4′OMe or C6′OMe), 55.42 (s,
C2′OMe or C4′OMe or C6′OMe), 42.43 (s, NMe′B), 41.22 (s,
NMe’A), 37.3 (dd, J = 2.7, 19.3, C1), 33.94 (d, J = 25.0, C3) 13.89 (d,
J = 30.2, PMe3). 31P NMR (CDCl3): δ −8.33 (JP−W = 284 Hz). CV
(DMA): Ep,a = 1.27 V. IR: νBH = 2507 cm−1, νNO + νIminium = 1587
cm−1. HRMS (M+) obsd (%), calcd (%), ppm: 809.26166 (96.1),
809.26311 (80.1), −1.8; 810.2647 (100), 810.26563 (81.4), −1.1;
811.26362 (99.7), 811.26564 (100), −2.5; 812.26717 (36.3),
812.26945 (48.4), −2.8; 813.26699 (86.7), 813.26884 (82.2), −2.3.
TpW(NO)(PMe3)N-3-chloro-4-(2,4,6-trimethoxyphenyl)-
cyclohexylidene)-N-methylmethanaminium](OTf) (32). In a 4-dram
vial charged with a stir bar, 1,3,5-trimethoxybenzene (0.302 g, 1.79
mmol) was added. To this were added a TfOH/DCM solution (1 mL,
0.0034 M) and MeCN (0.20 mL). This was stirred for 1 min. To this
mixture was added 29 (0.0915 g, 0.1089 mmol). After 1 h the reaction
was quenched, outside of the glovebox, by the addition of 50 mL of
saturated aqueous NaHCO3. The reaction mixture was extracted with
DCM (3 × 50 mL), dried over MgSO4, filtered through a Celite plug,
and concentrated in vacuo. The residue was redissolved in MeCN (3
mL), and Et2O (150 mL) was slowly added to induce the precipitation
of a light yellow solid. The solid was collected on a 15 mL fine-
porosity glass fritted funnel, giving 32 (0.0809 g, 0.082 mmol, 76%).
1H NMR (CDCl3): δ 8.11 (d, J = 2.0, 1H, Pz3B), 8.00 (d, J = 2.0,
1H, Pz5C), 7.95 (d, J = 2.0, 1H, Pz5B), 7.93 (d, J = 2.0, 1H, Pz5A),
7.56 (d, J = 2.0, 1H, Pz3C), 7.37 (d, J = 2.0, 1H, Pz3A), 6.46 (d, J =
2.0, 1H, Pz4B), 6.44 (d, J = 2.0, 1H, Pz4C), 6.41 (d, J = 2.0, 1H,
Pz4A), 6.33 (d, J = 2.32, 1H, H6′), 6.31 (d, J = 2.32, 1H, H6′), 5.37
(dt, J = 1.35, 6.99, 1H, H4), 5.13 (m, 1H, H5), 3.89 (s, 3H, H5′OMe),
3.86 (s, 3H, H7′OMe), 3.79 (m, 1H, H), 3.72 (s, 3H, H5′OMe), 3.51
(s, 3H, NMe’B), 3.31 (dd, J = 6.35, 18.19, 1H, H6 (syn)), 3.07 (dd, J =
7.48, 18.19, 1H, H6), 2.39 (d, J = 9.89, 1H, H2), 2.33 (s, 3H, NMe’A)
1.20 (d, J = 9.14, 9H, PMe3). 13C NMR (CDCl3): 161.37 (s, H5′ or
H7′), 161.15 (s, H5′ or H7′), 159.67 (s, H5′ or H7′), 145.1 (s, Pz3B),
1H NMR (CDCl3): δ 8.25 (br s, 1H, NH), 7.64 (d, 1H, J = 7.9,
H4′), 7.41 (d, 1H, J = 8.1, H7′), 7.25 (ddd, 1H, J = 0.9, 7.2, 8.1, H6′),
7.16 (ddd, 1H, J = 0.9, 7.2, 7.9, H5′ overlaps with H3), 7.13 (dd, 1H, J
= 3.4, 10.0, H3 overlaps with H5′), 7.01 (d, 1H, J = 2.2, H2′), 6.16
(dd, 1H, J = 2.2, 10.0, H2), 4.06 (br m, 1H, H4), 2.59−2.49 (m, 2H,
H6), 2.44−2.29 (m, 2H, H5). 13C NMR (CDCl3): δ 199.9 (s, C1),
153.3 (s, C3), 136.8 (s, C7a′), 129.5 (s, C2), 126.4 (s, C3a′), 122.6 (s,
C6), 121.6 (s, C2′), 119.9 (s, C5′), 118.8 (s, C4′), 116.6 (s, C3), 111.6
(s, C7′), 36.7 (s, C6), 33.7 (s, C4), 30.0 (s, C5). IR: νCO = 1673 cm−1,
νCC = 1658 cm−1. HRMS: [M + Na]+ obsd (%), calcd (%), diff.:
234.08967 (100), 234.08894 (100), 3.1
4-(1H-Indol-3-yl)phenol (34). In a fume hood, 12 (0.026 g, 0.036
mmol) was added and dissolved in 0.5 mL of acetone. The solution
was yellow and homogeneous. Finely ground CAN (0.022 g, 0.040
mmol) was added along with 0.5 mL of MeCN, and the solution
became green and heterogeneous. After monitoring for 5 days, the
reaction solution was added to 100 mL of Et2O, resulting in a
heterogeneous suspension, which gradually formed an oily residue
when allowed to settle. The suspension was filtered onto a 60 mL
medium-porosity fritted disk rinsed with 10 mL of Et2O. Solvent was
removed from the filtrate under vacuum, leaving a green residue. A 0.5
in. neutral alumina plug with 1 in. of sand on top of the alumina was
placed in a 60 mL medium-porosity fritted disk. The residue from the
filtrate was dissolved in 20 mL of Et2O and passed through the
alumina plug, then eluted with 400 mL of ether for fraction 1. The
column was then eluted with 40 mL of MeOH for fraction 2. Fraction
1 was discarded, and the solvent was removed from fraction 2 in vacuo,
leaving a green residue, 34. No yield for an isolated product was
obtained. 1H NMR (d6-acetone): δ 10.3 (br s, 1H, NH), 7.84 (dt, 1H,
J = 1.0, 8.0, H7′), 7.52 (d, 2H, J = 8.6, H3), 7.46 (s, 1H, H2′ overlaps
with H4′), 7.45 (m, 1H, H4′ overlaps with H2′), 7.14 (ddd, 1H, J =
1.0, 7.0, 8.0, H5′), 7.08 (ddd, 1H, J = 1.0, 7.0, 8.0, H6′), 6.93 (d, 1H, J
= 8.6, H2). 13C NMR (d6-acetone): δ 156.4 (s, C1), 138.1 (s, C7a′),
129.1 (s, C3), 128.4 (s, C4), 126.8 (s, C3a′), 122.4 (s, C2′ or C5′),
122.3 (s, C2′ or C5′), 120.2 (s, C6′), 120.1 (s, C7′), 117.9 (s, C3′),
116.4 (s, C2), 112.5 (s, C4′). LRMS: observed mass 209.
701
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2′,4′-Dimethoxy-2,3-dihydro-[1,1′-biphenyl]-4(1H)-one (35). In a
fume hood, 20 (0.1031 g, 0.11 mmol), CAN (0.1265 g, 0.23 mmol),
and acetone (5 mL) were combined in a test tube. The slurry was
sonicated for 15 min. The light red solution was added to a round-
bottom flask containing 20 mL of saturated aqueous NaHCO3 and
stirred. After 30 min, the reaction mixture was extracted with Et2O (3
× 50 mL). The Et2O layers were combined, dried over MgSO4, filtered
with a Celite plug, and concentrated in vacuo. The solid was
redissolved in small portions of DCM (3 × 0.3 mL) and loaded onto a
500 μm silica preparatory plate. The plate was eluted with 200 mL of
70:30 hexanes/EtOAc. A band at Rf = 0.46−0.53 was scraped off the
plate and placed in a test tube. To the test tube was added EtOAc (20
mL), and the mixture was sonicated for ∼20 min. The silica was
filtered over a 60 mL medium-porosity fritted funnel and washed with
EtOAc (100 mL). The filtrate was concentrated to a yellow oil, 35
(0.0096 g, 0.0418 mmol, 38%).
washed with 39 mL of EtOAc. The filtrate was concentrated in vacuo
to give 37 (12 mg, 0.048 mmol, 61%) as an oil.
1H NMR (CDCl3): δ 7.88 (s, NH), 7.70 (d, 1H, J = 8.0, H17), 7.36
(d, 1H, J = 8.1, H14), 7.23 (m, 1H, H15), 7.20 (m, 1H, H6 or H7),
7.16 (m, 1H, H6 or H7), 7.16 (m, 1H, H16), 7.13 (m, 1H, H5), 7.09
(d, 1H, J = 7.3, H8), 6.97 (d, 1H, J = 2.2, H12), 6.64 (dd, 1H, J = 2.1,
9.5, H4), 6.25 (dd, 1H, J = 3.8, 9.6, H3), 4.09 (ddd, 1H, J = 3.1, 6.8,
10.1, H2), 3.22 (dd, 1H, J = 7.2, 15.5, H1), 3.19 (dd, 1H, J = 10.3,
15.5, H1). 13C NMR (CDCl3): δ 136.8 (s, C18), 135.2 (s, C10), 133.9
(s, C9), 132.8 (s, C3), 128.2 (s, C8), 127.7 (s, C4), 127.3 (s, C6 or
C7), 126.8 (s, C6 or C7), 126.8 (s, C13), 126.2 (s, C5), 122.3 (s,
C16), 121.5 (s, C12), 119.5 (s, C15), 119.4 (s, C17), 118.8 (s, C11),
111.5 (s, C14), 35.6 (s, C1), 31.9 (s, C2).
2-(1,2-Dihydronaphthalen-2-yl)-1H-pyrrole (38). In a fume hood,
CAN (101 mg, 0.184 mmol) was weighed into a vial and dissolved in
water (2.02 g). 10 (120 mg, 0.172 mmol) was added to a vial and
dissolved in CHCl3 (2.79 g). The two solutions were combined, and
the mixture was vigorously stirred for 5 h. The mixture was diluted
with Et2O (40 mL) and extracted with water (2 × 15 mL). The water
layers were combined and extracted with four 20 mL portions of Et2O,
and the combined organic layers were dried over anhydrous MgSO4.
The MgSO4 was filtered on a 60 mL medium-porosity fritted funnel
and rinsed with Et2O (60 mL). The Et2O solution was concentrated in
vacuo, giving a brown oil, which was redissolved in minimal DCM and
precipitated by addition to 70 mL of stirring hexanes. The precipitate
was filtered over a 60 mL fine-porosity fritted funnel, washed with 30
mL of hexanes, and discarded. The filtrate was concentrated in vacuo
to give an orange solid. The solid was dissolved in small portions of
DCM (2 × 0.3 mL) and loaded onto a 500 μm silica preparatory plate.
The plate was eluted with 100 mL of 3:1 hexanes/EtOAc. A
fluorescent band at Rf = 0.7 was scraped off the plate and added into a
test tube with 20 mL of EtOAc. The test tube was sonicated for 20
min, and the silica was filtered over a 60 mL medium-porosity fritted
funnel and washed with 25 and 10 mL portions of EtOAc. The EtOAc
was concentrated in vacuo to give 38 (9 mg, 0.108 mmol, 28%) as a
light green oil.
1H NMR (CDCl3): δ 6.99 (d, J = 8.91, 1H, H6′), 6.94 (ddd, J =
1.15, 3.11, 10.02, 1H, H3), 6.49 (d, J = 2.36, 1H, H9′), 6.46 (dd, J =
2.36, 8.91, 1H, H8′), 6.13 (dd, J = 2.50, 10.02, 1H, H2), 4.06 (m, 1H,
H4) 3.83 (s, 3H, H5′OMe), 3.81 (s, 3H, H7′OMe), 2.48 (m, 2H, H6),
2.28 (m, 1H, H5), 2.01 (m, 1H, H5). 13C NMR (CDCl3): δ 200.30 (s,
C1), 160.30 (s, C5′/C7′), 158.12 (s, C5′/C7)′, 154.63 (s, C3), 130.02
(s, C2), 128.79 (s, C6′), 123.39 (s, C4′), 104.47 (s, C9′), 99.21 (s,
C8′), 55.75 (s, C5′OMe/C7′OMe), 55.73 (s, C5′OMe/C7′OMe),
37.42 (s, C6), 35.86 (s, C4), 30.62 (s, C5) IR: νCO = 1674 cm−1.
HRMS: (M + Na)+ obsd (%), calcd (%), ppm: 255.09902 (100),
255.09917 (100), −0.6; 256.10325 (18.1), 256.10256 (15.5), 2.7.
2′,4′,6′-Trimethoxy-2,3-dihydro-[1,1′-biphenyl]-4(1H)-one (36).
In a fume hood, 21 (0.1000 g, 0.106 mmol), CAN (0.1200 g, 0.218
mmol), and acetone (10 mL) were combined in a test tube. The slurry
was sonicated for 15 min. The light red slurry was added to a round-
bottom flask containing 20 mL of saturated aqueous NaHCO3
solution. After 25 min, the reaction mixture was extracted with Et2O
(3 × 50 mL). The Et2O layers were combined and washed with brine
(50 mL), dried over MgSO4, filtered through a Celite plug, and
concentrated in vacuo. The resulting solid was redissolved in small
portions of DCM (3 × 0.3 mL) and loaded onto a 500 μm silica
preparatory plate. The plate was eluted with 200 mL of 70:30 hexanes/
EtOAc. A band at Rf = 0.60−0.70 was scraped off the plate, and placed
in a test tube. To the test tube was added EtOAc (20 mL), and the
mixture was sonicated for ∼20 min. The silica was filtered on a 60 mL
medium-porosity fritted funnel and washed with EtOAc (100 mL).
The filtrate was concentrated to a yellow oil, 36 (0.0134 g, 0.0508
mmol, 48%).
1H NMR (CDCl3): δ 7.93 (s, 1H, NH), 7.20 (m, 1H, J = 7.1, H6),
7.16 (m, 1H, J = 7.5, H7), 7.12 (m, 1H, H8), 7.10 (m, 1H, H5), 6.61
(m, 1H, H14), 6.60 (d, 1H, J = 9.5, H4), 6.13 (m, 1H, H12), 6.10 (dd,
1H, J = 4.4, 9.4, H3), 6.01 (m, 1H, H13), 3.81 (m, 1H, H2), 3.19 (dd,
1H, J = 8.2, 15.5, H1), 3.00 (dd, 1H, J = 15.5, 7.2, H1′). 13C NMR
(CDCl3): δ 134.1 (s, C11), 134.0 (s, C9), 133.4 (s, C10), 130.7 (s,
C3), 128.2 (s, C8), 128.0 (s, C4), 127.7 (s, C7), 127.0 (s, C6), 126.3
(s, C5), 116.9 (s, C14), 108.3 (s, C12), 105.0 (s, C13), 35.5 (s, C1),
33.5 (s, C2).
1H NMR (CDCl3): δ 6.97 (dt, J = 1.90, 10.20, 1H, H2), 6.13 (s,
2H, H3′ and H5′), 5.98 (ddd, J = 1.0, 3.0, 10.20, 1H, H3), 4.23 (dddd,
J = 1.90, 3.0, 4.90, 11.30, 1H, H1), 3.82 (s, 3H, C4′ OMe), 3.77 (s, 6H,
C2′OMe and C6′OMe), 2.53 (m, 2H, C5), 2.37 (m, 1H, C6), 1.97
(m, 1H, C6). 13C NMR (CDCl3): δ 200.5 (s, C4), 169.14 (s, C2′,
C6′), 160.55 (s, C4′), 158.82 (C2), 127.11 (s, C3), 112.07 (s, C1′),
91.22 (s, C3′, C5′), 55.69 (s, 2′OMe, 4′OMe or 6′OMe), 55.51 (s,
2′OMe, 4′OMe or 6′OMe), 39.09 (s, C5), 33.50 (s, C1), 29.32 (s,
C6). IR: νCO = 1667 cm−1. HRMS (M + Na)+ obsd (%), calcd (%),
ppm: 285.11043 (100), 285.10973 (100), 2.5; 286.11306 (19.7),
286.11313 (16.6), −0.2
3-(1,2-Dihydronaphthalen-2-yl)-1H-indole (37). In a fume hood, 9
(60 mg, 0.080 mmol) was mixed with acetone (1.986 g). A solution of
CAN (44 mg, 0.080 mmol) in water (1.496 g) was added to give a
heterogeneous solution, which was stirred rapidly for 1.5 h. The slurry
was diluted with 20 mL of Et2O and washed with water (3 × 10 mL).
The water layers were combined and back-extracted with Et2O (2 × 10
mL). The Et2O layers were combined and dried over anhydrous
MgSO4. The MgSO4 was filtered on a 30 mL medium-porosity fritted
funnel, and the Et2O filtrate was concentrated in vacuo to yield an
orange solid. The solid was redissolved in small portions of DCM (2 ×
0.3 mL) and loaded onto a 250 μm silica preparatory plate. The plate
was eluted with 100 mL of 70:30 hexanes/ethyl acetate (EtOAc). A
large band with Rf = 0.8 was scraped into a test tube, to which 20 mL
of EtOAc was added. The test tube was sonicated for 20 min, and the
slurry was filtered on a 60 mL medium-porosity fritted funnel and
5-(1,2-Dihydronaphthalen-2-yl)-2,3-dimethylfuran (39). In a
fume hood, CAN (47 mg, 0.086 mmol) was added to a vial and
dissolved in water (1.416 g). 11 (62 mg, 0.085 mmol) was added to a
second vial and dissolved in acetone (1.511 g). The two solutions were
combined, and the mixture was stirred for 30 min before being diluted
with Et2O (30 mL) and extracted with water (2 × 15 mL). The water
layers were combined and extracted with Et2O (4 × 10 mL). The Et2O
layers were combined and dried over anhydrous MgSO4. The MgSO4
was filtered on a 60 mL medium-porosity fritted funnel, and the filtrate
was concentrated in vacuo to give a light orange solid. The solid was
dissolved in DCM and precipitated over 30 mL of stirring hexanes.
The resulting solid was filtered on a 30 mL fine-porosity fritted funnel
and discarded. The filtrate was concentrated in vacuo, dissolved in
small portions of DCM (2 × 0.3 mL), and loaded onto a 250 μm silica
preparatory plate. The preparatory plate was eluted with 100 mL of
3:1 hexanes/EtOAc. A large band at Rf = 0.8−0.9 was scraped off the
plate into a test tube. EtOAc (20 mL) was added to the test tube, and
the slurry was sonicated for 25 min. The silica was filtered on a 60 mL
medium-porosity fritted funnel and washed with 20 mL of EtOAc. The
EtOAc was concentrated in vacuo to give 39 as an oil (9 mg, 0.0399
mmol, 47%) with a small amount of substituted naphthalene as an
impurity.
1H NMR (CDCl3): δ 7.13−7.17 (m, 3H, H6, H7, and H8), 7.09 (d,
1H, J = 7.3, H5), 6.58 (dd, 1H, J = 2.2, 9.6, H4), 6.07 (dd, 1H, J = 3.8,
9.5, H3), 5.84 (s, 1H, H12), 3.69 (ddd, 1H, J = 3.0, 6.5, 10.2 H2), 3.07
702
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Organometallics
Article
(dd, 1H, J = 7.0, 15.4, 1H), 2.97 (dd, 1H, J = 10.4, 15.4 H1′), 2.13 (s,
1H, H15), 1.85 (s, 1H, H16). 13C NMR (CDCl3): δ 155.0 (s, C11),
146.6 (s, C14), 135.1 (s, C9), 134.3 (s, C10), 130.1 (s, C3), 129.0 (s,
C6, C7, or C8), 128.7 (s, C4), 128.3 (s, C6, C7, or C8), 127.7 (s, C6,
C7, or C8), 127.1 (s, C5), 115.2 (s, C13), 109.0 (s, C12), 34.8 (s, C2),
33.9 (s, C1), 11.4 (s, C15), 10.0 (s, C16).
(24) Ding, F.; Valahovic, M. T.; Keane, J. M.; Anstey, M. R.; Sabat,
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D. J. Am. Chem. Soc. 2008, 130, 12472.
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W. D. J. Am. Chem. Soc. 2008, 130, 6906.
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ASSOCIATED CONTENT
■
S
* Supporting Information
Full experimental procedures for all previously unpublished
compounds and descriptions of their spectroscopic analysis.
CIF files for 9, 12, 13, and 32; H and 13C NMR spectra of
1
selected compounds. This information is available free of
charge via the Internet at http://pubs.acs.org.
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3118.
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177.
AUTHOR INFORMATION
■
Author Contributions
⊥These authors contributed equally.
Notes
(35) Fox, J. M.; Huang, X.; Chieffi, A.; Buchwald, S. L. J. Am. Chem.
Soc. 2000, 122, 1360.
The authors declare no competing financial interest.
(36) Kawatsura, M.; Hartwig, J. F. J. Am. Chem. Soc. 1999, 121, 1473.
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ACKNOWLEDGMENTS
■
Acknowledgement is made to the NSF (CHE-1152803 (UVA);
CHE-0116492 (UR); CHE0320699 (UR)).
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