Stereoselective Formation of η6-Arene Ruthenium(II) Complexes via Metal-Triggered Bergman and Hopf Cycloaromatizations

Article abstract of DOI:10.1021/acs.organomet.7b00679

A stereoselective metal-mediated cycloaromatization of chiral conjugated dienynes and enediynes is described. For dienyne cycloaromatization, placement of the carbon stereocenter in the allylic position gives the highest diastereomeric ratios (dr). The observed stereoselectivity depends on the steric bulk of the alkyne substituent, as replacing a propargylic methyl for trimethylsilyl increases the dr from 56:44 to 80:20. For both enediyne and dienyne substrates, [(η⁵-C₅Me₅)Ru(NCMe)₃]PF₆ exhibits greater diastereoselectivity than does [(η⁵-C₅H₅)Ru(NCMe)₃]PF₆. For the same chiral enediyne substrate, [(η⁵-C₅Me₅)Ru(NCMe)₃]PF₆ generates a 4:1 ratio of diastereomeric arene products, whereas both [(η⁵-C₅Me₄CF₃)Ru(NCMe)₃]PF₆ and [(η⁵-C₅H₅)Ru(NCMe)₃]PF₆ generate a 1:1 product mixture, indicative of a significant electronic influence of the ancillary ligand on diastereoselectivity. X-ray structure determination of several isolated ruthenium arene diastereomers confirms the assigned relative stereochemistry for the major and minor stereoisomeric metal arene products. Arene-binding experiments demonstrate that the observed stereoselectivity does not involve complexation of free arene by ruthenium.

Full text of DOI:10.1021/acs.organomet.7b00679

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Cite This: Organometallics XXXX, XXX, XXX-XXX
Stereoselective Formation of η6‑Arene Ruthenium(II) Complexes via
Metal-Triggered Bergman and Hopf Cycloaromatizations
David M. Hitt,†,§ Ryan L. Holland,† Kim K. Baldridge,*,‡ Stephen K. Cope,†
and Joseph M. O’Connor*,†
†Department of Chemistry, University of California, San Diego, La Jolla, California 92093, United States
‡Health Sciences Platform, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, China
S
* Supporting Information
ABSTRACT: A stereoselective metal-mediated cycloaromati-
zation of chiral conjugated dienynes and enediynes is
described. For dienyne cycloaromatization, placement of the
carbon stereocenter in the allylic position gives the highest
diastereomeric ratios (dr). The observed stereoselectivity
depends on the steric bulk of the alkyne substituent, as
replacing a propargylic methyl for trimethylsilyl increases the
dr from 56:44 to 80:20. For both enediyne and dienyne
substrates, [(η5-C5Me5)Ru(NCMe)3]PF6 exhibits greater
diastereoselectivity than does [(η5-C5H5)Ru(NCMe)3]PF6.
For the same chiral enediyne substrate, [(η5-C5Me5)Ru-
(NCMe)3]PF6 generates a 4:1 ratio of diastereomeric arene products, whereas both [(η5-C5Me4CF3)Ru(NCMe)3]PF6 and
[(η5-C5H5)Ru(NCMe)3]PF6 generate a 1:1 product mixture, indicative of a significant electronic influence of the ancillary ligand
on diastereoselectivity. X-ray structure determination of several isolated ruthenium arene diastereomers confirms the assigned
relative stereochemistry for the major and minor stereoisomeric metal arene products. Arene-binding experiments demonstrate
that the observed stereoselectivity does not involve complexation of free arene by ruthenium.
substrates in which the benzenoid fragment is nonsymmetric
(e.g., R1 ≠ R2), cycloaromatization results in the formation of
planar chiral sandwich complexes 2-CpX, in which the (η5-CpX)
Ru (CpX = Cp, Cp*, Cp‡) fragment can bind to either face of
the benzannulated arene.7
INTRODUCTION
■
Cationic ruthenium(II) η6-arene complexes are valuable
auxiliaries for stereoselective processes and serve as activating
groups for several difficult aromatic transformations (e.g.,
nucleophilic substitution, dearomatization, and aromatic CH
lithiation).1,2 Furthermore, half-sandwich ruthenium(II) com-
plexes can trigger or promote challenging chemical trans-
formations en route to η6-arene complexes; we demonstrated
previously the ability of [(η5-C5R4R′)Ru(NCMe)3]PF6 com-
plexes (1-Cp, R = R′ = H; 1-Cp*, R = R′ = Me; 1-Cp‡, R = Me,
R′ = CF3) to act as a metal trigger for the formal Bergman3 and
Hopf4 cycloaromatization of enediynes 2-Ene and dienynes 2-
Dien, respectively (Scheme 1).5,6 In the case of six-π-electron
For 2-Dien and 2-Ene, incorporation of a stereocenter at
either the allylic or propargylic position could potentially allow
for stereoinductive addition of the (η5-C5R4R′)Ru moiety, thus
demonstrating diastereoselectivity in the course of a one-pot
cycloaromatization/η6-complexation reaction. Several method-
ologies exist to prepare chiral metal η6-arene complexes with
enhanced stereoselectivity from benzenoid precursors,8,9 but
few exist that work to both cycloaromatize acyclic precursors
and complex a metal diastereoselectively. The most widely
developed of these reactions is the Dotz benzannulation.10 For
̈
Scheme 1. Cyclopentadienylruthenium-Triggered Hopf and
Bergman Cycloaromatizations5,6
example, Wulff and co-workers utilized chromium carbene 3 in
combination with bulky, chiral propargylic ether 4-Alkyne to
give very high diastereomeric ratios in favor of (CO)3Cr(η6-
arene) complex 4-Cr(CO)3 (Scheme 2).10q Since our initial
report,5 metal-triggered Bergman cyclizations have been further
developed: for instance, Kundig reported the chromium-
̈
mediated cyclization of enediyne 5-Ene to give the cyclo-
aromatized complex 5-Cr(CO)3, which binds selectively to the
least hindered face of an 11-membered enediyne ring.11 This
Received: September 6, 2017
© XXXX American Chemical Society
A
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Scheme 2. Established Stereoselective Metal-Mediated
Cycloaromatizations10q11
Scheme 3. Synthetic Route to Dienynes 6-Dien-All and 6-
Dien-Pro
was then lithiated and quenched with acetaldehyde to give 6-
Dien-Pro.
When allyl-substituted dienyne 6-Dien-All (24 μmol) was
treated with a slight excess of 1-Cp* (37 μmol) in chloroform-d
and monitored by 1H NMR spectroscopy, immediate formation
of two new (η5-C5Me5)Ru complexes 6-Cp* was observed, with
resonances at δ 1.86 and 1.88 (s, 15H). Cycloaromatization was
suggested by the appearance of two corresponding sets of aryl
resonances that integrated in a total 15:3 ratio with the
1
respective Cp* signal in the H NMR spectrum (δ 1.86:5.51
(d), 5.59 (d), and 5.85 (s); 1.88:5.50 (d), 5.57 (s), and 5.93
(d)). Integration relative to 1,3,5-tri-tert-butylbenzene as
internal standard indicated the formation of 6-Cp* in 70%
combined yield, with a diastereomeric ratio of 62:38 (Scheme 4
cycloaromatization was also triggered by ruthenium complex 1-
Cp*, which gave a mixture of diastereomers. Alternatively, the
preparation of 5-Aryl by a thermal Bergman cyclization,
followed by isolation and treatment with 1-Cp*, gave (η5-
C5Me5)Ru(η6-arene) complex 5-Cp* in 28% yield as a single
diastereomer. In each case, the cyclic nature of the substrate
and the pendant spectator alkene substituent limit access to one
face of the substrate, thereby enforcing a preference for metal
binding. By utilizing a dienyne or enediyne substrate with a
freely rotating stereocenter, we envisaged a stereochemical
influence whereby the handedness of the chiral substituent
would proscribe certain combinations of (η5-CpX)Ru cation
and substrate, resulting in pronounced diastereoselectivity. We
herein report the first examples of facially selective metal η6-
arene binding by stereoinductive control of free rotors in metal-
triggered Bergman and Hopf cycloaromatizations.
Scheme 4. Initial Observation of Stereoinduction in the
Dienyne Cycloaromatization
and Table 1, entry 1). In contrast, reaction of the propargyl-
substituted dienyne 6-Dien-Pro (19 μmol) with 1-Cp* (28
μmol) proceeded under similar conditions to give 6-Cp* in
94% yield with no apparent stereoselectivity (entry 2). While
both substrates gave 6-Cp* in good to excellent yield, only 6-
Dien-All with the stereocenter located in the allylic position was
stereoselective.
Optimistic about the observed diastereomeric ratio, a series
of dienynes with variable substitution were prepared (see the
Experimental Section) and screened with 1-Cp* to investigate
the requisite structural features for stereoselectivity (Table 1);
furtherinformed by the initial observations with 6-Dienthe
target substrates all incorporate a 1-alkoxyalkyl stereocenter at
the allylic position. Substrate 10-Dien bearing a 1-methoxyethyl
group at the allylic position and a methyl group at the
propargylic position gave the highest observed diastereoselec-
tivity (69:31 dr, entry 5), while the alcohol variant 8-Dien gave
a similar yield with slightly decreased selectivity (entry 3). In
RESULTS AND DISCUSSION
■
Dienyne Stereoselectivity: Discovery and Substrate
Scope. Dienynes 6-Dien-All and 6-Dien-Pro containing an
allylic and propargylic stereocenter, respectively, were chosen as
ideal starting points for initial reactivity studies due to their
common precursor 7 (available in two steps from cyclo-
hexanone)12 and their expected convergent cycloaromatization
with [(η5-C5Me5)Ru(NCMe)3]PF6 (1-Cp*) to afford the
monosubstituted [(η5-C5Me5)Ru(η6-tetralin)]PF6 complexes
(6-Cp*). Synthesis of both substrates commenced from
TMS-substituted enynal 7 (Scheme 3). Wittig olefination of
7 followed by sodium borohydride reduction and desilylation
gave the secondary allylic alcohol 6-Dien-All. Similarly,
olefination of 7 to the monosubstituted alkene followed by
TMS deprotection yielded the terminal alkyne. This product
B
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Table 1. Exploring Substrate Scope with Dienynes and Enediynes Containing a Stereocenter
a
b
entry
substrate
product
R1
H
R2
R3
solvent
time
yield, %/(dr)
1
6-Dien-All
6-Dien-Pro
8-Dien
6-Cp*
6-Cp*
8-Cp*
9-Cp*
10-Cp*
11-Cp*
Me
H
CDCl3
<15 min
<15 min
<15 min
3.5 h
70/(62:38)
94/(50:50)
97/(64:36)
78/(63:37)
94/(69:31)
44/(52:48)
decomp
2
1-(OH)Et
Me
CDCl3
3
H
Me
Me
Me
i-Pr
Me
Me
Me
Me
Me
Me
CDCl3
c
4
9-Dien
Et
Me
H
Me
CDCl3
5
10-Dien
11-Dien
12-Dien
8-Ene
Me
CDCl3
<15 min
<15 min
23 h
d
6
Me
CDCl3
7
H
TMS
Me
CDCl3
e
8
8-Cp*
12-Cp*
10-Cp
12-Cp
12-Cp‡
H
acetone-d6
acetone-d6
CDCl3
<15 min
<15 min
<15 min
>30 min
<15 min
87/(56:44)
56/(80:20)
ef
,
9
12-Ene
H
TMS
Me
10
11
12
10-Dien
12-Ene
Me
H
102/(58:42)
e
TMS
TMS
acetone-d6
acetone-d6
30/(50:50)
g
12-Ene
H
32/(50:50)
a
b
Reactions run with 1.2−1.5 equiv of 1-Cp* at 0.02−0.006 M with respect to substrate with 1,3,5-tri-tert-butylbenzene as internal standard. Yield
c
d
e
and dr determined by 1H NME. Reaction stopped at 91% conversion of 9-Dien; yield based on conversion. Product was not isolated. γ-terpinene
as H-atom source. Reaction tested in CDCl3, acetone-d6, THF-d8, and acetone-d6/THF-d8 mixture with no effect on dr. 1,4-Cyclohexadiene as H-
f
g
atom source.
general, the reaction was adversely affected by increased steric
bulk beyond a methyl substituent in any of the modified
positions (entries 4, 6, and 7). While still diastereoselective,
ethyl substitution at the alkoxy position slowed the cyclo-
aromatization considerably (9-Dien; entry 4), whereas isopropyl
substitution at the stereocenter did not retard the reaction but
gave a much lower yield and essentially no stereoselectivity (11-
Dien; entry 6). Finally, the trimethylsilyl-substituted dienyne
12-Dien reacted with 1-Cp* but failed to form products 12-Cp*
(entry 7).
Scheme 5. Synthetic Route to Enediynes 8-Ene and 12-Ene
Enediyne Stereoselectivity: Discovery and Substrate
Scope. As a starting point for investigating the potential
stereoselectivity of the ruthenium-triggered enediyne cyclo-
aromatization reaction, we chose to prepare two cyclo-
hexenediynes (8-Ene and 12-Ene) containing a 1-hydroxyethyl
stereocenter, while also varying the substitution at the other
alkyne terminus. Common intermediate 7 was converted to the
asymmetric enediyne 13-Ene under Corey−Fuchs conditions
(Scheme 5). Lithiation of 13-Ene followed by quenching with
acetaldehyde gave the TMS-substituted alcohol 12-Ene, which
was desilylated, lithiated, and quenched with methyl iodide to
give the methyl-substituted alcohol 8-Ene.
When a mixture of 12-Ene (5 μmol) and 1-Cp* (8 μmol)
with γ-terpinene (27 μmol) as H atom donor was dissolved in
acetone-d6 and monitored by 1H NMR spectroscopy,
immediate formation of two sets of resonances consistent
with the product structure 12-Cp* were observed (Table 1,
entry 9). Integration of the TMS resonances for the 12-Cp*-
maj (δ 0.46) and 12-Cp*-min (δ 0.44) diastereomers in
comparison to internal standard showed that the compounds
formed in an 8:2 ratio in a combined NMR yield of 56%.
Performing the reaction in chloroform-d, THF-d8, or an
acetone-d6/THF-d8 mixture showed no improvement in yield
or dr.
in the formation of the previously isolated product 8-Cp* in
comparably high yield (87% vs 97%) but with lower
stereoselectivity (56:44 vs 64:32 dr; Table 1, entry 8 vs entry
3, respectively). Despite the low dr, the major and minor
isomers of 8-Cp* formed are consistent for both the dienyne
and enediyne cycloaromatization.
[(η5-CpX)Ru(NCMe)3]PF6 Stereoselectivity: Assessing
the Effect of the Metal−Ligand Environment. It was
anticipated that the relative steric bulk and the electronic nature
of the cyclopentadienyl ligand would have an effect on the
selectivity of the dienyne and enediyne cyclizations. To probe
the influence of the ancillary ligand environment, the best
performing dienyne and enediyne were tested with unsub-
stituted [(η5-C5H5)Ru(NCMe)3]PF6 (1-Cp). When dienyne
10-Dien (6 μmol) was treated with 1-Cp (9 μmol) in
chloroform-d, cycloaromatization was observed to give
products 10-Cp in apparent 102% combined yield with a
diastereomeric ratio of 58:42 (Table 1, entry 10), versus 94%
Reaction of 8-Ene (11 μmol) with 1-Cp* (16 μmol) under
identical conditions (acetone-d6; γ-terpinene 55 μmol) resulted
C
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yield and a 69:31 dr with 1-Cp* (entry 5). Cyclization of the
enediyne substrate 12-Ene (18 μmol) with 1-Cp (20 μmol) in
acetone-d6, with γ-terpinene (90 μmol) as H atom donor, gave
the expected products 12-Cp in only 30% yield with no
observed diastereoselectivity (entry 11), whereas the formation
of 12-Cp* products with 1-Cp* proceeded to products in 56%
yield with an 80:20 dr (entry 9). These results suggest that
either the smaller steric size or the decreased electron-donating
ability of the Cp ligand lowers the dr of both the dienyne and
enediyne cycloaromatizations.
isomers and also showed a conserved stereochemical relation-
ship between the carbon stereocenter and the planar chirality of
the (η5-C5R5)Ru(η6-arene) binding for the major and minor
diastereomers of each pair. In each case, the major stereoisomer
has the smallest stereocenter substituent (hydrogen) directed
toward the ortho position on the aromatic ring when the
oxygen substituent is rotated syn with the metal fragment, as
depicted in Figure 2.
To better delineate whether the poor selectivity of 1-Cp was
a result of an electronic or a steric effect, [(η5-C5Me4CF3)Ru-
(NCMe)3]PF6 (1-Cp‡) was tested with enediyne 12-Ene.
Previous work by Gassman established the monotrifluorome-
thylated 1-trifluoromethyl-2,3,4,5-tetramethylcyclopentadienyl
ligand (η5-C5Me4CF3, Cp‡) to be similar in electron-donating
ability to the unsubstituted cyclopentadienyl ligand, while
having a steric profile similar to the well-established
pentamethylcyclopentadienyl ligand.13 Cycloaromatization of
12-Ene (20 μmol) with 1-Cp‡ (21 μmol) and 1,4-cyclo-
hexadiene (1,4-CHD, 42 μmol) as an H atom donor in
acetone-d6 afforded the corresponding 12-Cp‡ diastereomers in
a 1:1 ratio with a 36% combined yield (entry 12). The similar
yield and lack of selectivity of 1-Cp and 1-Cp‡ with 12-Ene
suggests that, for this particular substrate, the electronic nature
of the (CpX)Ru moiety exerted the predominant effect in
determining the stereochemical outcome of enediyne cyclo-
aromatization.
Figure 2. Generalized stereochemical model for predicting the major
and minor stereoisomeric products of the dienyne and enediyne
cycloaromatizations (upper panel). Generalized representations of the
four stereoisomeric products from reaction of 1-CpX with dienynes and
enediynes (lower panel).
Solid-State Structure Determination of the [(η5-CpX)-
Ru(η6-tetralin)]PF6 Products. The crystalline nature of the
cationic cyclopentadienyl ruthenium arene complexes allowed
for solid-state X-ray structure determinations on the major and
minor diastereomers of 10-Cp* (Supporting Information) and
10-Cp (Figure 1), as well as the minor diastereomers of 6-Cp*
and 8-Cp* (Supporting Information). This analysis confirmed
the diastereomeric relationship between the major and minor
On a preparative scale, complex 12-Cp*-maj was isolated
pure after repeated chromatography, but 12-Cp*-min proved
unisolable due to a facile TMS migration to give the OTMS
isomer 14-Cp*-min (eq 1). To establish the relative stereo-
chemistry for complexes 12-Cp*, single-crystal samples grown
from isolated 12-Cp*-maj and from a mixture of 12-Cp*-min/
14-Cp*-min were subjected to X-ray crystallographic analysis.
In both cases, the solid-state structures obtained were of the
TMS-migrated products, 14-Cp*-maj and 14-Cp*-min. It is
unclear if the isomerizations of 12-Cp* to 14-Cp* are intra- or
intermolecular, but regardless of the mechanism, it is highly
unlikely that the TMS migration affects either the carbon
stereocenter or the planar chirality of the metal fragment, and
the stereochemical assignments of 12-Cp*-maj and 12-Cp*-min
are inferred to correlate with 14-Cp*-maj and 14-Cp*-min,
respectively.
Arene-Binding Experiments. Two basic mechanisms can
be envisioned for the stereoselective dienyne and enediyne
cycloaromatizations: (i) the metal remains coordinated to the
substrate throughout the reaction and is bound stereoselectively
as a consequence of the cyclization or (ii) the metal catalytically
Figure 1. ORTEP drawings of the cations of 10-Cp-maj (upper panel)
and 10-Cp-min (lower panel). The hexafluorophosphate anion and all
hydrogen atoms except the stereocenter hydrogen at C1 are omitted
for clarity.
D
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cyclizes the substrate and then binds stereoselectively to the
newly formed arene in a subsequent step.
Uemura and co-workers have demonstrated the facially
selective binding of chiral, ortho-substituted benzylic alcohols
(15) with 1-Cp to form (η5-C5H5)Ru(η6-arene) complexes 15-
Cp (Scheme 6).9 The stereoselectivity of these reactions was
enediyne cyclization conditions (acetone-d6; γ-terpinene, 55
μmol; 1-Cp*, 16 μmol) resulted in rapid formation of 8-Cp*
(entry 2) but in low conversion, as γ-terpinene competed with
the arene for binding of 1-Cp*, resulting in the formation of
[(η5-C5Me5)Ru(η6-p-cymene)]PF6 from the dehydrogenation
of γ-terpinene. Performing the reaction without γ-terpinene (8-
Aryl, 11 μmol; 1-Cp*, 16 μmol; entry 3) resulted in a similar
yield and dr, with high conversion of 8-Aryl. In all cases the
major and minor diastereomeric products are spectroscopically
consistent with those formed from the cyclization reactions
and, most importantly, binding of the free arene with 1-Cp*
resulted in a significantly higher stereoselectivity than the
reactions of 1-Cp* with dienyne 8-Dien or enediyne 8-Ene,
suggesting that binding scenario ii is inoperative.
Scheme 6. Stereoselective (η5-C5H5)Ru(η6-arene)
Complexation of Chiral, Ortho-Substituted Benzylic
Alcohols9
Computational Analysis of the Diastereomeric Ruthe-
nium Arene Complexes. In order to address the relative
thermodynamic stabilities of the diastereomeric ruthenium
arene products, BP86/Def2-TZVPP calculations were under-
taken on 10-Cp-maj, 10-Cp-min, 10-Cp*-maj, and 10-Cp*-min
(Figure 3 and Table S9 in the Supporting Information). The
calculated 2.7 kcal/mol energy difference between 10-Cp-maj
and 10-Cp-min is nearly identical with the 2.8 kcal/mol energy
difference between 10-Cp*-maj and 10-Cp*-min. In both cases,
the lower energy diastereomer corresponds to the major isomer
formed experimentally (Table 1, entries 5 and 10). This
substantial energy difference indicates that a thermodynamic
product ratio for two arene diastereomers in each pair would
have been >120:1.
For both pairs of arene diastereomers the Ru−arene-
(centroid) distance is shorter for the major isomer than for
the minor isomer. This contrasts with the Ru−Cp(centroid)
and Ru−Cp*(centroid) distances, which are nearly identical in
the four complexes (1.832−1.834 Å). The major diastereomers
in each set have C2−C1−C3−Ru torsion angles of 179.7° (10-
Cp-maj-calc) and 178.8° (10-Cp*-maj-calc), which places the
methyl substituent distal to ruthenium. In the minor
diastereomers these torsion angles are 11.8° (10-Cp-min-calc)
and −78.8° (10-Cp*-min-calc), thereby placing the C2 methyl
proximal to ruthenium. In methoxycyclohexane the equatorial
isomer is 0.75 kcal/mol more stable than the axial isomer,
whereas for methylcyclohexane that energy difference is 1.70
kcal/mol. Thus, the positioning of the C2 methyl relative to
ruthenium appears to significantly influence the relative
stabilities of the major and minor diastereomers.
rationalized by a proposed precomplexation equilibrium with
the hydroxy substitutent, whereby facial selectivity of the arene
is enforced by minimizing steric interactions between the ortho
and stereocenter substituents of the arene. Although not a
direct comparison, binding of the Uemura substrates appears to
occur with greater stereoselectivity (dr >92:8 in all cases;
Scheme 6, inset) in comparison to that observed for the
dienyne and enediyne substrates in this study, suggesting an
alternative binding mechanism.
To distinguish between the two η6-complexation mecha-
nisms, an arene-binding experiment was performed in which 6-
(1-hydroxyethyl)-7-methyltetralin (8-Aryl)the arene formed
from cyclization of 8-Dien or 8-Enewas bound by reaction
with 1-Cp* to give η6-arene complexes 8-Cp* (Table 2).
Substrate 8-Aryl is readily accessible by sodium borohydride
reduction of commercially available 6-acetyl-7-methyltetralin.
Reaction of arene 8-Aryl (34 μmol) with 1-Cp* (51 μmol)
under dienyne cyclization conditions (CDCl3; no H atom
source) resulted in slow complexation (70 h; 48% conversion)
to form 8-Cp* in excellent yield (99%) and diastereomeric ratio
(85:15) (Table 2, entry 1). Subjecting 8-Aryl (11 μmol) to
Table 2. Arene-Binding Experiments
a
b
entry
arene conversion, %
H atom donor
solvent
time
70 h
yield, %/(dr)
99/(85:15)
1
2
3
48
36
95
solvent
CDCl3
c
γ-terpinene
solvent
acetone-d6
acetone-d6
<50 min
<50 min
99/(87:13)
91/(81:19)
a
b
Reactions run with 1.5 equiv of 1-Cp* at 0.02−0.06 M with respect to substrate with 1,3,5-tri-tert-butylbenzene as internal standard. Yield and dr
c
determined by H NMR. Accompanied by formation of [(η5-C5Me5)Ru(η6-p-cymene)]PF6.
1
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simple complexation of the benzenoid product. Future studies
will be focused toward developing a mechanistic model to
account for the stereoselectivity, as well as identification of
metal/ligand systems that proceed with higher diastereoselec-
tivity.
EXPERIMENTAL SECTION
■
General Information. All manipulations were carried out under
an atmosphere of dry dinitrogen using standard Schlenk or glovebox
techniques. NMR-scale ruthenium cyclization reactions were per-
formed under a dry dinitrogen atmosphere in 5 mm J. Young style
NMR tubes equipped with a Teflon needle-valve adapter using freshly
degassed solvents (freeze/pump/thaw procedure). Chloroform-d was
dried and stored over calcium hydride under a dinitrogen atmosphere.
Acetone-d6 was dried over freshly activated 4 Å molecular sieves for 5
h under a dinitrogen atmosphere before transfer in vacuo to a separate
Straus flask. Toluene, hexanes, diethyl ether, methylene chloride, and
tetrahydrofuran were dried on columns of activated alumina using a J.
C. Meyer (formerly Glass Contour) solvent purification system.
Methanol was purchased as the anhydrous DriSolv from Sigma-Aldrich
and used as received. [(η5-C5Me5)Ru(NCMe)3]PF6 was synthesized
according to the literature procedure.14 All other literature compounds
were prepared according to the indicated reference or were purchased
from commercial suppliers and used as received. Preparative thin-layer
chromatography (PTLC) was performed using glass plates precoated
with silica gel (1 mm, 60 Å pore size, EMD Chemicals) and visualized
by exposure to ultraviolet light. Flash column chromatographic
purification of synthetic intermediates and substrates was performed
using silica gel (60 Å, particle size 43−60 μm, 230−400 mesh, EMD
Chemicals), activated neutral Brockmann Activity grade I (150 mesh,
Sigma-Aldrich), or reverse-phase octadecylsilane bonded to silica gel
(particle size 40 μm, 60 Å, J. T. Baker).
Instrumentation. NMR spectra were recorded on Varian Mercury
300 (1H, 300 MHz; 13C 75.5 MHz), Varian Mercury 400 (1H, 400
MHz; 13C 100.7 MHz), Jeol ECA 500 (1H, 500 MHz), and Varian VX
1
500 (1H, 500 MHz; 13C 125 MHz) spectrometers. H and 13C{1H}
NMR chemical shifts (δ) are reported in parts per million (ppm)
relative to tetramethylsilane (1H and 13C, δ 0.00 ppm), with reference
to the residual proton or carbon resonance for CDCl3 (1H, δ 7.26
ppm; 13C δ 77.16 ppm) or acetone-d6 (1H, δ 2.05 ppm; 13C, δ 29.84
ppm). Infrared (IR) spectra were recorded on a Nicolet Avatar 360
FT-IR instrument with KBr or NaCl plates as thin films or JASCO FT-
IR 4100 attenuated total reflectance (ATR) platform (3 mm) using
ZnSe plates (thin films). High-resolution mass spectra were obtained
by the University of California, San Diego Mass Spectrometry Facility.
Melting points are uncorrected and were recorded on a Stanford
Research Systems EZ-Melt apparatus.
Computation. The structural and energetic analyses of the
molecular systems described in this study were carried out using the
BP86 density functional,15,16 with an ultrafine grid, together with the
Def2-TZVPP basis set.17 The effects of solvent were included using
the continuum solvation model, COSab, on the basis of the original
theory of Klamt modified for ab initio theory,18,19 with a dielectric for
trichloromethane. Full geometry optimizations were performed and
uniquely characterized via second derivative (Hessian) analysis to
establish stationary points and effects of zero point energy and thermal
corrections. Visualization and analysis of structural results were carried
out using Avogadro.20
(E)-4-(2-Ethynylcyclohex-1-enyl)but-3-en-2-ol (6-Dien-All).
NaBH4 (25 mg, 0.662 mmol) was added to a stirred solution of 7
(102 mg, 0.414 mmol) in MeOH/THF (4 mL, 1:1). After 10 min of
stirring at 23 °C, anhydrous K2CO3 (171 mg, 1.24 mmol) was added.
After 16 h of stirring at 23 °C, the reaction mixture was then diluted
with water (8 mL) and extracted with Et2O. The organic extract was
washed with brine (4 mL), dried over MgSO4, concentrated, and
purified by PTLC (8/2 hexanes/EtOAc) to afford 6-Dien-All as a
peach solid (52 mg, 71% yield). Mp: 41−43 °C. IR (KBr, thin film):
3299 (s, CspH), 2084 (CC) cm−1. 1H NMR (400 MHz, CDCl3): δ
1.30 (d, 3JHH = 7 Hz, 3H, CH3), 1.57−1.69 (m, 4H, 4,5-CH2), 1.70 (s,
Figure 3. From top to bottom, calculated structures for cations of 10-
Cp-maj-calc, 10-Cp-min-calc, 10-Cp*-maj-calc, and 10-Cp*-min-calc.
CONCLUSION
■
In summary, we have demonstrated the first examples of
stereoselective metal η6-arene complexation for ruthenium(II)-
mediated cycloaromatization of chiral dienynes and enediynes
that contain freely rotating stereocenters. We have identified
(1) several important structural features of the metal system
and substrate needed for stereoinduction, (2) a consistent
relative stereochemistry of the major and minor diastereomeric
products for both the dienyne and enediyne cycloaromatiza-
tions, (3) the importance of ancillary ligand electronic effects
on diastereoselectivity, and (4) arene-binding experiments
which suggest that the diastereoselectivity does not arise from
F
DOI: 10.1021/acs.organomet.7b00679
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Organometallics
Article
1H, OH), 2.19−2.30 (m, 4H, 3,6-CH2), 3.25 (s, 1H, CCH), 4.42
236−239 °C. 1H NMR (300 MHz, CDCl3): δ 1.55 (d, 3JHH = 6.5 Hz,
3H, CH(OH)CH3), 1.86 (s, 15H, Cp*), 1.59−1.94 (m, 4H, 2,3-CH2),
2.31−2.46 (m, 3H, 1,4-CHsyn, OH), 2.66−2.88 (m, 2H, 1,4-CHanti),
4.57 (dq, 3JHH = 6.5 Hz, 4.5 Hz, 1H, CH(OH)CH3), 5.51 (d, 3JHH = 6
3
3
(p, JHH = 7 Hz, 1H, C(H)OH), 5.79 (dd, JHH = 16 Hz, 7 Hz, 1H,
CHCHC(H)OH), 6.94 (d, 3JHH = 16 Hz, 1H, CHCHC(H)OH).
13C{1H} NMR (100 MHz, CDCl3): δ 22.1 (CH2), 22.3 (CH2), 23.5
(CH2), 25.2 (CH2), 30.8 (CH3), 69.3 (C(H)OH), 82.3 (CCH),
83.8 (CCH), 119.0 (CC), 129.8 (CHCH), 133.6 (CHCH),
141.3 (CC). HRMS-(EI) (m/z): [M + H]+ calcd for C12H16O,
176.1196; found, 176.1194.
3
4
Hz, 1H, 7/8-CArH), 5.59 (dd, JHH = 6 Hz, JHH = 1 Hz, 1H, 7/8-
CArH), 5.85 (s, 1H, 5-CArH). 13C{1H} NMR (75 MHz, CDCl3): δ
10.2 (CpCH3), 21.9 (2 × CH2), 26.0 (CH2), 26.1 (CH2), 27.1
(CH(OH)CH3), 66.7 (CH(OH)CH3), 83.2 (CArH), 83.9 (CArH),
86.4 (CArH), 95.0 (Cp*), 100.8 (CAr), 101.1 (CAr), 108.0 (CAr).
HRMS-(EI) (m/z): [M + H]+ calcd for C22H31ORu.F6P, 407.1445;
found, 407.1453. (6-Cp*-min): Mp. (dec) 254−258 °C. 1H NMR
(400 MHz, CDCl3): δ 1.55 (d, 3JHH = 6 Hz, 3H, CH(OH)CH3), 1.88
(s, 15H, Cp*), 1.61−1.92 (m, 4H, 2,3-CH2), 2.36−2.47 (m, 2H, 1,4-
4-(2-Vinylcyclohex-1-en-1-yl)but-3-yn-2-ol (6-Dien-Pro). A
2.5 M solution of n-BuLi (0.940 mL, 2.34 mmol) in hexanes was
added to a stirred heterogeneous mixture of [MePPh3]Br (836 mg,
2.34 mmol) in THF (78 mL) at −78 °C. The resulting yellow solution
was warmed to 23 °C, and a solution of 7 (303 mg, 1.47 mmol) in
THF (3.8 mL) was added over 15 min. After it was stirred at 23 °C for
2 h, the reaction mixture was poured over saturated aqueous NH4Cl
(150 mL) and extracted with Et2O (200 mL). The organic extracts
were washed with brine (150 mL), dried over Na2SO4, concentrated,
and purified by flash column chromatography (silica gel, 99/1
hexanes/EtOAc) to afford the TMS-substituted dienyne as a clear
oil. Anhydrous K2CO3 (610 mg, 4.41 mmol) was added to a stirred
solution of the resulting product in MeOH/THF (15 mL, 1/1) at 23
°C. After 4 h of stirring at 23 °C, the reaction mixture was filtered
through a fritted funnel, concentrated, diluted with aqueous 1 M HCl
(30 mL) and extracted with Et2O (30 mL). The organic extracts were
washed with 1 M HCl (20 mL), water (20 mL), and brine (20 mL),
dried over MgSO4, concentrated, and purified by flash column
chromatography (silica gel, 99/1 hexanes/EtOAc) to afford the
terminal alkyne as a clear oil (153 mg, 1.16 mmol). A 1 M solution of
LiHMDS (3.47 mL, 3.47 mmol) in THF was added to a stirred
solution of the resulting product in THF (12 mL) at 0 °C. After the
mixture was stirred at 0 °C for 30 min, acetaldehyde (0.325 mL, 5.80
mmol) was added. After this mixture was stirred at 0 °C for 30 min,
the reaction mixture was poured over saturated aqueous NH4Cl (30
mL) and extracted with Et2O (30 mL). The organic extracts were
washed with brine (30 mL), dried over MgSO4, concentrated, and
purified by flash column chromatography (silica gel, 8/2 hexanes/
EtOAc) to afford 6-Dien-All as a clear oil (76 mg, 29% yield over three
3
CHsyn), 2.53 (d, JHH = 5 Hz, 1H, OH), 2.70−2.82 (m, 2H, 1,4-
CHanti), 4.59 (qd, 3JHH = 6 Hz, 5 Hz 1H, CH(OH)CH3), 5.50 (d, 3JHH
3
= 6 Hz, 1H, 7/8-CArH), 5.57 (s,1H, 5-CArH), 5.93 (d, JHH = 6 Hz,
1H, 7/8-CArH). 13C{1H} NMR (75 MHz, CDCl3): δ 10.3 (CpCH3),
21.76 (CH2), 21.83 (CH2), 25.8 (CH2), 26.3 (CH2), 27.1 (CH(OH)
CH3), 66.6 (CH(OH)CH3), 82.5 (CArH), 84.5 (CArH), 87.0 (CArH),
95.0 (Cp*), 100.6 (CAr), 101.2 (CAr), 107.9 (CAr). HRMS-(EI) (m/z):
[M + H]+ calcd for C22H31ORu.F6P, 407.1445; found, 407.1449.
(E)-4-(2-(Prop-1-ynyl)cyclohex-1-enyl)but-3-en-2-ol (8-Dien)
and (E)-1-(3-Methoxybut-1-enyl)-2-(prop-1-ynyl)cyclohex-1-
ene (10-Dien). A 1 M solution of LiHMDS (16.5 mL, 16.5 mmol)
in THF was added to a stirred solution of 6-Dien-All (725 mg, 4.11
mmol) in THF (41 mL) at 0 °C. After 20 min of stirring at 0 °C,
iodomethane (1.53 mL, 24.7 mmol) was added. After 24 h of stirring
while gradually warming to 23 °C, the reaction mixture was poured
over saturated aqueous NH4Cl (80 mL) and extracted with Et2O (80
mL). The organic extracts were washed with brine (100 mL), dried
over MgSO4, concentrated, and purified by flash column chromatog-
raphy (silica gel). Using a lower concentration of EtOAc as eluent
(96:4 hexanes/EtOAc) afforded 10-Dien as a yellow oil (425 mg, 51%
yield). Continued elution with a slightly more polar solvent system
(92:8 hexanes/EtOAc) afforded 8-Dien as a yellow oil (168 mg, 21%
1
yield). (8-Dien): IR (ZnSe, neat): 3348 (OH) cm−1. H NMR (400
3
MHz, CDCl3): δ 1.31 (d, JHH = 6.5 Hz, 3H, CH(OH)CH3), 1.50 (s,
1
steps). IR (NaCl, neat): 3332 (OH), 2208 (CC) cm−1. H NMR
1H, OH), 1.56−1.68 (m, 4H, 4,5-CH2), 2.03 (s, 3H, CCCH3),
2.16−2.26 (m, 4H, 3,6-CH2), 4.39−4.47 (m, 1H, CH(OH)CH3), 5.73
(dd, 3JHH = 16 Hz, 7 Hz, 1H, CHCHC(OH)H), 6.93 (d, 3JHH = 16
Hz, 1H, CHCHC(OH)H). 13C{1H} NMR (75 MHz, CDCl3): δ 4.8
(CCCH3), 22.3 (CH2), 22.5 (CH2), 23.6 (CH2), 25.2 (CH2), 31.4
(CHCH3), 69.6 (C(OH)H), 79.8 (CC), 91.1 (CC), 120.9 (C
C), 130.5 (CHCH), 132.4 (CHCH), 138.1 (CC). HRMS-(EI)
(m/z): [M + H]+ calcd for C13H18O, 190.1352; found, 190.1349. (10-
(400 MHz, CDCl3): δ 1.51 (d, 3JHH = 7 Hz, 3H, CH3), 1.57−1.71 (m,
4H, 4,5-CH2), 1.76−1.81 (m, 1H, OH), 2.19−2.29 (m, 4H, 3,6-CH2),
3
4.67−4.77 (m, 1H, C(H)OH), 5.09 (d, JHH = 11 Hz, 1H, CH
3
C(Hcis)H), 5.25 (d, JHH = 17.5 Hz, 1H, CHC(Htrans)H), 7.05 (dd,
3JHH = 17.5 Hz, 11 Hz, 1H, CHCH2). 13C{1H} NMR (100 MHz,
CDCl3): δ 22.1 (CH2), 22.4 (CH2), 24.5 (CH2), 24.8 (CH2), 30.9
(CH3), 59.1 (CH(OH)), 84.1 (CC), 96.1 (CC), 113.3 (CH
CH2), 119.4 (CC), 136.9 (CHCH2), 140.9 (CC). HRMS-(EI)
(m/z): [M + H]+ calcd for C12H16O, 176.1196; found, 176.1195.
General Procedure for Dienyne and Enediyne Cyclization
Reactions and Arene-Binding Experiments. Dienyne, enediyne,
or arene substrate and 1,3,5-tri(tert-butyl)benzene (0.5−1 mg) were
added to a J-Young style NMR tube fitted with a Teflon needle-valve
adapter. In the case of enediyne substrates, an H atom donor (γ-
terpinene or 1,4-CHD) was also added. The J-Young NMR tube was
evacuated on a high-vacuum Schlenk line, and deuterated solvent was
transferred in vacuo with standard Schlenk techniques. An initial NMR
experiment was conducted to establish relative ratios of starting
material to internal standard. In an inert-atmosphere glovebox the J-
Young NMR tube was uncapped, ruthenium complex 1-CpX was
added to the reaction solution, recapped, and immediately analyzed by
NMR spectroscopy. Additional NMR experiments were conducted, if
necessary, until complete consumption of dienyne, enediyne, or arene
starting materials.
1
3
Dien). H NMR (500 MHz, CDCl3): δ 1.27 (d, JHH = 6 Hz, 3H,
CH(OCH3)CH3), 1.56−1.67 (m, 4H, 4,5-CH2), 2.03 (s, 3H, C
CCH3), 2.18−2.25 (m, 4H, 3,6-CH2), 3.27 (s, 3H, OCH3), 3.83 (dq,
3JHH = 8 Hz, 6 Hz, 1H, CH(OCH3)CH3), 5.54 (dd, JHH = 16 Hz, 8
3
3
Hz, 1H, CHCHC(OCH3)H), 6.88 (d, JHH = 16 Hz, 1H, CH
CHC(OCH3)H). 13C{1H} NMR (100 MHz, CDCl3): δ 4.8 (C
CCH3), 21.9 (CH2), 22.3 (CH2), 22.6 (CH2), 25.2 (CH2), 31.4
(CHCH3), 56.1 (OCH3), 78.7 (C(OCH3)H), 79.9 (CC), 90.9
(CC), 120.6 (CC), 130.4 (CHCH), 132.3 (CHCH), 138.2
(CC). HRMS-(EI) (m/z): [M + H]+ calcd for C14H20O, 204.1509;
found, 204.1506.
4-(2-(Prop-1-ynyl)cyclohex-1-enyl)but-3-yn-2-ol (8-Ene). An-
hydrous K2CO3 (300 mg, 2.17 mmol) was added to a stirred solution
of 12-Ene (80 mg, 0.325 mmol) in THF/MeOH (4 mL, 1/1) at 23 °C.
After it was stirred at 23 °C for 3 h, the reaction mixture was diluted
with water (10 mL) and extracted with Et2O (15 mL). The organic
extract was washed with brine (10 mL), dried over MgSO4, and
concentrated to give the desilylated product as a yellow oil (48 mg,
85% yield). A 1 M solution of LHMDS (1.4 mL, 1.38 mmol) in THF
was added to a stirred solution of the resulting product in THF (3
mL) at 0 °C. After the mixture was stirred at 0 °C for 20 min,
iodomethane (0.103 mL, 1.65 mmol) was added. After it was stirred
for 4 h while being slowly warmed to 23 °C, the reaction mixture was
poured over saturated aqueous NH4Cl (10 mL) and extracted with
Et2O (10 mL). The organic extracts were washed with brine (10 mL),
(η5-Pentamethylcyclopentadienyl)(η6-6-(1-hydroxyethyl)-
tetralinyl)ruthenium(II) Hexafluorophosphate (6-Cp*). After 30
min at 23 °C, the NMR scale reaction mixture of 6-Dien-Pro with 1-
Cp* was concentrated and purified by flash column chromatography
(alumina, 95:5 CH2Cl2/acetone) followed by crystallization (CH2Cl2/
Et2O) to afford a mixture of 6-Cp*-maj and 6-Cp*-min as a colorless
solid (4.2 mg, 31% yield). 6-Cp*-maj and 6-Cp*-min were isolated
after repeated alumina chromatography. (6-Cp*-maj): Mp. (dec)
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DOI: 10.1021/acs.organomet.7b00679
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Organometallics
Article
dried over MgSO4, concentrated, and purified by flash column
chromatography (silica gel, 95/5 hexanes/EtOAc) to afford 8-Ene as a
yellow oil (35 mg, 63% yield). IR (ZnSe, thin film): 3348 (OH) cm−1.
was added to a stirred solution of the resulting product in THF (2
mL) at 0 °C. After 20 min of stirring at 0 °C, iodomethane (0.058 mL,
0.93 mmol) was added. After 16 h of stirring with gradual warming to
23 °C, the reaction mixture was poured over saturated aqueous NH4Cl
(4 mL) and extracted with Et2O (4 mL). The organic extracts were
washed with brine (4 mL), dried over MgSO4, concentrated, and
purified by reverse-phase column chromatography (C18-bonded silica
gel, 9/1 MeOH/H2O) to afford 9-Dien as a clear oil (21 mg, 16% over
two steps). 1H NMR (400 MHz, CDCl3): δ 1.20 (t, 3JHH = 7 Hz, 3H,
3
1H NMR (400 MHz, CDCl3): δ 1.50 (d, JHH = 6 Hz, 3H,
3
CH(OH)CH3), 1.55−1.63 (m, 4H, 4,5-CH2), 1.79 (d, JHH = 5.5 Hz,
1H, OH), 2.02 (s, 3H, CCCH3), 2.15−2.22 (m, 4H, 3,6-CH2), 4.71
3
(app pentet, JHH = 6 Hz, 1H, CH(OH)CH3). 13C{1H} NMR (100
MHz, CDCl3): δ 4.7 (CCCH3), 22.0 (2 × CH2), 24.7 (CH2), 29.9
(CH2), 30.5 (CH(OH)CH3), 59.1 (CH(OH)CH3), 80.5 (CC),
85.1 (CC), 90.1 (CC), 94.1 (CC), 124.1 (CC), 127.5 (C
C). HRMS-(EI) (m/z): [M + H]+ calcd for C13H16O.Na, 211.1093;
found, 211.1097.
3
CH2CH3), 1.28 (d, JHH = 7 Hz, 3H, CH(OEt)CH3), 1.56−1.68 (m,
4H, 4,5-CH2), 2.03 (s, 3H, CCCH3), 2.18−2.26 (m, 4H, 3,6-CH2),
3.37 (dq, 2JHH = 9 Hz, 3JHH = 7 Hz, 1H, C(H)H′CH3), 3.51 (dq, 2JHH
3
3
= 9 Hz, JHH = 7 Hz, 1H, C(H)H′CH3), 3.96 (p, JHH = 7 Hz, 1H,
6-(1-Hydroxyethyl)-7-methyltetralin (8-Aryl). NaBH4 (130 mg,
3.43 mmol) was added to a stirred solution of 6-acetyl-7-methyltetralin
(215 mg, 1.14 mmol) in THF/MeOH (12 mL, 1/1) at 23 °C. After it
was stirred for 30 min at 23 °C, the reaction mixture was poured over
acetone (5 mL), concentrated, diluted with H2O (10 mL), and
extracted with Et2O (10 mL). The organic extracts were washed with
brine (10 mL), dried over Na2SO4, and concentrated to afford 8-Aryl
as a pale yellow oil (210 mg, 97% yield). IR (ZnSe, neat): 3332 (OH)
3
CH(OEt)CH3), 5.58 (dd, JHH = 16 Hz, 7 Hz, 1H, CH
3
CHCH(OEt)CH3), 6.88 (d, JHH = 16 Hz, 1H, CHCHCH(OEt)-
CH3). 13C{1H} NMR (100 MHz, CDCl3): δ 4.8 (CCCH3), 15.6
(CH2CH3), 22.2 (CH2), 22.3 (CH2), 22.6 (CH2), 25.2 (CH2), 31.3
(CH(OEt)CH3), 63.6 (CH2CH3), 76.8 (CH(OEt)CH3), 79.9 (C
C), 90.8 (CC), 120.4 (CC), 131.0 (CHCH), 131.6 (CH
CH), 138.3 (CC). HRMS-(EI) (m/z): [M + H]+ calcd for
C15H23O, 219.1743; found, 219.1742.
1
3
cm−1. H NMR (400 MHz, CDCl3): δ 1.47 (d, JHH = 6 Hz, 3H,
(η5-Pentamethylcyclopentadienyl)(η6-6-(1-ethoxyethyl)-7-
methyltetralinyl)ruthenium(II) Hexafluorophosphate (9-Cp*).
After 3.5 h at 23 °C, the NMR-scale reaction mixture of 9-Dien with 1-
Cp* was concentrated and purified by flash column chromatography
(alumina, CH2Cl2) to afford a mixture of 9-Cp*-maj and 9-Cp*-min as
CH(OH)CH3), 1.69 (s, 1H, OH), 1.74−1.83 (m, 4H, 2,3-CH2), 2.29
3
(s, 3H, ArCH3), 2.69−2.79 (m, 4H, 1,4-CH2), 5.08 (q, JHH = 6 Hz,
1H, CH(OH)CH3), 6.86 (s, 1H, ArH), 7.21 (s, 1H, ArH). 13C{1H}
NMR (100 MHz, CDCl3): δ 18.5 (ArCH3), 23.4 (CH2), 23.5 (CH2),
24.1 (CH(OH)CH3), 29.0 (CH2), 29.2 (CH2), 66.8 (CH(OH)CH3),
125.2 (CArH), 131.1 (CArH), 131.4 (CAr), 135.1 (CAr), 136.1 (CAr),
141.2 (CAr). HRMS-(EI) (m/z): [M + H]+ calcd for C13H18O.Na,
213.1250; found, 213.1251.
1
a colorless solid (14 mg, 63% yield). H NMR (400 MHz, CDCl3): δ
1.22 (t, 3JHH = 7 Hz, 3H, min-CH2CH3), 1.30 (t, 3JHH = 7 Hz, 3H, maj-
3
CH2CH3), 1.38 (d, JHH = 6 Hz, 3H, maj−CH(OH)CH3), 1.48 (d,
3JHH = 6.5 Hz, 3H, min−CH(OH)CH3), 1.80 (s, 15H, maj-Cp*), 1.81
(s, 15H, min-Cp*), 1.56−1.86 (m, 8H, 2,3-CH2), 2.10 (s, 3H, maj-
ArCH3), 2.22 (s, 3H, min-ArCH3), 2.31−2.46 (m, 4H, 1,4-CHsyn),
(η5-Pentamethylcyclopentadienyl)(η6-6-(1-hydroxyethyl)-7-
methyltetralinyl)ruthenium(II) Hexafluorophosphate (8-Cp*).
After 19 h at 23 °C, the NMR-scale reaction mixture of 8-Dien with 1-
Cp* was concentrated and purified by flash column chromatography
(silica gel, 95/5 CH2Cl2/acetone) followed by crystallization
(CH2Cl2/Et2O) to afford both 8-Cp*-maj and 8-Cp*-min (11.6 mg,
63% combined yield). 8-Cp*-maj was produced as a colorless solid,
while 8-Cp*-min recrystallized as light brown plates. Data for 8-Cp*-
maj are as follows. Mp: 274−276 °C dec. IR (ZnSe, thin film): 3579
2
3
2.68−2.77 (m, 4H, 1,4-CHanti), 3.45 (dq, JHH3 = 9 Hz, JHH = 7 Hz,
2
2H, C(H)H′CH3), 3.71 (dq, JHH = 9 Hz, JHH = 7 Hz, 1H, min-
2
3
C(H)H′CH3), 3.84 (dq, JHH = 9 Hz, JHH = 7 Hz, 1H, maj-
3
C(H)H′CH3), 4.28 (q, JHH = 6.5 Hz, 1H, min-CH(OH)CH3), 4.30
(q, 3JHH = 6 Hz, 1H, maj-CH(OH)CH3), 5.48 (s, 1H, min-ArH), 5.61
(s, 1H, min-ArH), 5.67 (s, 2H, maj-ArH). 13C{1H} NMR (100 MHz,
CDCl3): δ 9.8 (maj-CpCH3), 10.0 (min-CpCH3), 15.65 (maj-CH3),
15.74 (maj-CH3), 16.0 (min-CH3), 16.3 (min-CH3), 17.8 (min-CH3),
20.6 (maj-CH3), 21.8 (1 × maj-CH2, 2 × min-CH2), 21.9 (maj-CH2),
25.4 (min-CH2), 25.6 (maj-CH2), 25.8 (min-CH2), 25.9 (maj-CH2),
63.7 (maj-CH2CH3), 64.2 (min-CH2CH3), 70.3 (maj-CH(OH)CH3),
73.5 (min-CH(OH)CH3), 83.3 (maj-CArH), 85.1 (min-CArH), 89.2
(maj-CArH), 90.1 (min-CArH), 94.0 (maj-Cp*), 94.2 (min-Cp*), 95.5
(maj-CAr), 98.5 (min-CAr), 100.0 (maj-CAr), 100.8 (min-CAr), 101.7
(min-CAr), 101.8 (maj-CAr), 103.0 (min-CAr), 105.7 (maj-CAr). HRMS-
(EI) (m/z): [M + H]+ calcd for C25H37ORu.F6P, 449.1915; found,
449.1927.
1
3
(OH) cm−1. H NMR (400 MHz, CDCl3): δ 1.48 (d, JHH = 6.5 Hz,
3H, CH(OH)CH3), 1.55−1.65 (m, 1H, 2/3-CHsyn), 1.81 (s, 15H,
Cp*), 1.72−1.87 (m, 3H, 2,3-CH2), 2.08 (s, 3H, ArCH3), 2.33−2.41
(m, 2H, 1,4-CHsyn), 2.66−2.80 (m, 2H, 1,4-CHanti), 2.82 (d, 3JHH = 5.5
3
Hz, 1H, OH), 4.75 (dq, JHH = 6.5 Hz, 5.5 Hz, 1H, CH(OH)CH3),
5.45 (s, 1H, ArH), 5.87 (s, 1H, ArH). 13C{1H} NMR (100 MHz,
CDCl3): δ 9.8 (CpCH3), 15.7 (ArCH3), 21.8 (CH2), 21.9 (CH2), 25.2
(CH(OH)CH3), 25.6 (CH2), 25.7 (CH2), 63.7 (CH(OH)CH3), 83.1
(CArH), 88.7 (CArH), 94.2 (Cp*), 95.6 (CAr), 100.5 (CAr), 101.1
(CAr), 106.5 (CAr). HRMS-(EI) (m/z): [M + H]+ calcd for
C23H33ORu.F6P, 421.1602; found, 421.1606. Data for 8-Cp*-min are
as follows. Mp: 268−270 °C dec. IR (ZnSe, thin film): 3559 (OH)
(η5-Pentamethylcyclopentadienyl)(η6-6-(1-methoxyethyl)-7-
methyltetralinyl)ruthenium(II) Hexafluorophosphate (10-Cp*).
Ruthenium complex 1-Cp* (34 mg, 0.068 mmol) was added to a
solution of 10-Dien (12 mg, 0.058 mmol) in CDCl3 at 23 °C in a
glovebox. After 30 min at 23 °C, the reaction mixture was
concentrated and purified by repeated PTLC (CH2Cl2/acetone
mixtures) followed by recrystallization (EtOAc/CH2Cl2/hexanes) to
afford isolated samples of 10-Cp*-maj and 10-Cp*-min as colorless
1
3
cm−1. H NMR (400 MHz, CDCl3): δ 1.56 (d, JHH = 6.5 Hz, 3H,
CH(OH)CH3), 1.81 (s, 15H, Cp*), 1.64−1.84 (m, 4H, 2,3-CH2),
3
2.27 (s, 3H, ArCH3), 2.33−2.41 (m, 2H, 1,4-CHsyn), 2.64 (d, JHH
=
=
6.5 Hz, 1H, OH), 2.68−2.80 (m, 2H, 1,4-CHanti), 4.68 (pentet, 3JHH
6.5 Hz, 1H, CH(OH)CH3), 5.39 (s, 1H, ArH), 5.58 (s,1H, ArH).
13C{1H} NMR (100 MHz, CDCl3): δ 10.0 (CpCH3), 16.3 (ArCH3),
21.76 (CH2), 21.78 (CH2), 22.2 (CH(OH)CH3), 25.5 (CH2), 25.7
(CH2), 66.8 (CH(OH)CH3), 85.2 (CArH), 90.1 (CArH), 94.0 (Cp*),
98.8 (CAr), 100.8 (CAr), 101.4 (CAr), 103.6 (CAr). HRMS-(EI) (m/z):
[M + H]+ calcd for C23H33ORu.F6P, 421.1602; found, 421.1607.
(E)-1-(3-Ethoxybut-1-enyl)-2-(prop-1-ynyl)cyclohex-1-ene
(9-Dien). Triethylsilyltrifluoromethanesulfonate (0.41 mL, 1.812
mmol) was added to a stirred solution of 6-Dien-All (106 mg, 0.604
mmol, 0.10 M) and imidazole (123 mg, 1.812 mmol, 0.30 M) in THF
(6 mL) at 23 °C. After 10 min of stirring at 23 °C, the reaction
mixture was quenched with saturated aqueous NH4Cl (12 mL) and
extracted with Et2O (12 mL). The organic extracts were washed with
saturated NH4Cl (2 × 12 mL), dried over MgSO4, concentrated, and
purified by flash column chromatography (alumina, hexanes) to afford
a clear oil. A 1 M solution of LHMDS (0.56 mL, 0.56 mmol) in THF
1
solids. Data for 10-Cp*-maj are as follow.s Mp: 274−277 °C dec. H
3
NMR (400 MHz, CDCl3): δ 1.39 (d, JHH = 6 Hz, 3H,
CH(OMe)CH3), 1.80 (s, 15H, Cp*), 1.52−1.88 (m, 4H, 2,3-CH2),
2.11 (s, 3H, ArCH3), 2.27−2.47 (m, 2H, 1,4-CHsyn), 2.66−2.78 (m,
3
2H, 1,4-CHanti), 3.47 (s, 3H, OCH3), 4.20 (q, JHH = 6 Hz, 1H,
CH(OMe)CH3), 5.62 (s, 1H, ArH), 5.68 (s, 1H, ArH). 13C{1H} NMR
(100 MHz, CDCl3): δ 9.8 (Cp*), 15.7 (CH3), 19.9 (CH3), 21.8
(CH2), 21.9 (CH2), 25.6 (CH2), 25.8 (CH2), 56.0 (OCH3), 71.9
(CH(OMe)CH3), 83.2 (CArH), 89.1 (CArH), 94.1 (Cp*), 95.9 (CAr),
100.0 (CAr), 101.7 (CAr), 105.3 (CAr). HRMS-(EI) (m/z): [M + H]+
calcd for C24H35ORu.F6P, 441.1726; found, 441.1725. Data for 10-
1
Cp*-min are as follows. Mp: 196−197 °C dec. H NMR (400 MHz,
3
CDCl3): δ 1.47 (d, JHH = 6 Hz, 3H, CH(OMe)CH3), 1.81 (s, 15H,
H
DOI: 10.1021/acs.organomet.7b00679
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Cp*), 1.62−1.87 (m, 4H, 2,3-CH2), 2.21 (s, 3H, ArCH3), 2.35−2.45
(m, 2H, 1,4-CHsyn), 2.68−2.78 (m, 2H, 1,4-CHanti), 3.40 (s, 3H,
OCH3), 4.17 (q, 3JHH = 6 Hz, 1H, CH(OMe)CH3), 5.41 (s, 1H, ArH),
5.63 (s, 1H, ArH). 13C{1H} NMR (100 MHz, CDCl3): δ 10.0 (Cp*),
16.4 (CH3), 17.5 (CH3), 21.8 (2 × CH2), 25.4 (CH2), 25.7 (CH2),
56.1 (OCH3), 75.9 (CH(OMe)CH3), 85.8 (CArH), 90.1 (CArH), 94.3
(Cp*), 98.2 (CAr), 100.9 (CAr), 101.4 (CAr), 103.4 (CAr). HRMS-(EI)
(m/z): [M + H]+ calcd for C24H35ORu.F6P, 441.1726; found,
441.1727.
C). HRMS-(EI) (m/z): [M + H]+ calcd for C14H22OSi.Na, 257.1332;
found, 257.1334.
(E)-4-Methyl-1-(2-(prop-1-ynyl)cyclohex-1-enyl)pent-1-en-3-
ol (11-Dien). 2-Iodoxybenzoic acid21 (373 mg, 1.33 mmol, 0.21 M)
was added to a solution of 11-Dien-Precursor-2 (208 mg, 0.887 mmol)
in EtOAc (6.5 mL), refluxed for 6 h, cooled to 23 °C, filtered, and
concentrated to afford a yellow oil (215 mg, 0.925 mmol). A 2 M
solution of i-PrMgCl (0.93 mL, 1.85 mmol) in THF was added to a
stirred solution of the resulting product in THF (10 mL) at 0 °C. After
20 min of stirring at 0 °C, the reaction mixture was quenched with
MeOH (3 mL), diluted with saturated aqueous NH4Cl (15 mL), and
extracted with Et2O (20 mL). The organic extracts were washed with
water (2 × 10 mL) and brine (10 mL), dried over MgSO4, and
concentrated to afford a yellow oil. Anhydrous K2CO3 (112 mg, 0.814
mmol) was added to a stirred solution of the resulting product in
MeOH/THF (3 mL, 1/1) at 23 °C. After 4 h of stirring at 23 °C, the
reaction mixture was filtered through a fritted funnel, concentrated,
diluted with aqueous 1 M HCl (5 mL), and extracted with Et2O (5
mL). The organic extracts were washed with 1 M HCl (5 mL), water
(5 mL), and brine (5 mL), dried over MgSO4, concentrated, and
purified by flash column chromatography (silica gel, 96/4 hexanes/
EtOAc) to afford the terminal alkyne as a yellow oil (44 mg, 0.215
mmol). A 1 M solution of LHMDS (0.70 mL, 0.698 mmol) in THF
was added to a stirred solution of the resulting product in THF (2
mL) at 0 °C. After 20 min of stirring at 0 °C, iodomethane (0.067 mL,
1.075 mmol) was added. After 1 h of stirring with gradual warming to
23 °C, the reaction mixture was poured over saturated aqueous NH4Cl
(4 mL) and extracted with Et2O (4 mL). The organic extracts were
washed with brine (4 mL), dried over MgSO4, concentrated, and
purified by flash column chromatography (silica gel, 96/4 hexanes/
EtOAc) to afford 11-Dien as a clear oil (22 mg, 11% yield over four
steps). IR (ZnSe, neat): 3332 (OH) cm−1. 1H NMR (400 MHz,
CDCl3): δ 0.90 (d, 3JHH = 7 Hz, 3H, CH(CH3)CH3), 0.96 (d, 3JHH = 7
Hz, 3H, CH(CH3)CH3), 1.46 (m, 1H, OH), 1.56−1.69 (m, 4H, 4,5-
(η5 -Cyclopentadienyl)(η6 -6-(1-methoxyethyl)-7-
methyltetralinyl)ruthenium(II) Hexafluorophosphate (10-Cp).
After 30 min at 23 °C, the NMR-scale reaction mixture of 10-Dien
with 1-Cp was concentrated and purified by flash column
chromatography (silica gel, CH2Cl2) followed by crystallization
(CH2Cl2/Et2O) to afford a mixture of 10-Cp-maj and 10-Cp-min as
a colorless solid. 10-Cp-maj and 10-Cp-min were each isolated after
repeated flash column chromatography (silica gel). Data for 10-Cp-maj
are as follows. Mp: 167−169 °C. 1H NMR (300 MHz, CDCl3): δ 1.40
3
(d, JHH = 6 Hz, 3H, CH(OMe)CH3), 1.66−1.91 (m, 4H, 2,3-CH2),
2.31 (s, 3H, ArCH3), 2.53−2.84 (m, 4H, 1,4-CH), 3.49 (s, 3H,
OCH3), 4.34 (q, 3JHH = 6 Hz, 1H, CH(OMe)CH3), 5.17 (s, 5H, Cp),
6.11 (s, 1H, ArH), 6.17 (s, 1H, ArH). 13C{1H} NMR (75 MHz,
CDCl3): δ 17.8 (CH3), 20.7 (CH3), 22.3 (CH2), 22.4 (CH2), 27.7
(CH2), 28.3 (CH2), 57.1 (OCH3), 73.2 (CH(OMe)CH3), 81.4 (Cp),
81.5 (CArH), 87.8 (CArH), 98.2 (CAr), 101.4 (CAr), 102.7 (CAr), 106.4
(CAr). HRMS-(EI) (m/z): [M + H]+ calcd for C19H25ORu.F6P,
365.0976; found, 365.0977. Data for 10-Cp-min are as follows. Mp:
1
3
188−189 °C. H NMR (400 MHz, CDCl3): δ 1.51 (d, JHH = 6 Hz,
3H, CH(OMe)CH3), 1.69−1.89 (m, 4H, 2,3-CH2), 2.36 (s, 3H,
ArCH3), 2.64−2.83 (m, 4H, 1,4-CH), 3.36 (s, 3H, OCH3), 4.37 (q,
3JHH = 6 Hz, 1H, CH(OMe)CH3), 5.19 (s, 5H, Cp), 6.12 (s, 1H,
ArH), 6.14 (s, 1H, ArH). 13C{1H} NMR (100 MHz, CDCl3): δ 18.3
(CH3), 20.7 (CH3), 22.2 (CH2), 22.3 (CH2), 27.8 (CH2), 28.1 (CH2),
57.2 (OCH3), 74.4 (CH(OMe)CH3), 81.5 (Cp), 84.0 (CArH), 87.7
(CArH), 100.1 (CAr), 101.6 (CAr), 102.8 (CAr), 106.1 (CAr). HRMS-
(EI) (m/z): [M + H]+ calcd for C19H25ORu.F6P, 365.0976; found,
365.0979.
3
CH2), 1.76 (octet, JHH = 7 Hz, 1H, CH(CH3)2), 2.03 (s, 3H, C
3
CCH3), 2.17−2.27 (m, 4H, 3,6-CH2), 3.94 (t, JHH = 7 Hz, 1H,
3
CH(OH)CH), 5.70 (dd, JHH = 16 Hz, 7.5 Hz, 1H, CH
3
CHCH(OH)CH), 6.93 (d, JHH = 16 Hz, 1H, CHCHCH(OH)-
(E)-Ethyl 3-(2-((Trimethylsilyl)ethynyl)cyclohex-1-enyl)-
a c r y l a t e ( 1 1 - D i e n - P r e c u r s o r - 1 ) . E t h y l
(triphenylphosphoranylidene)acetate (1.87 g, 5.37 mmol) and 7
(1.00 g, 4.85 mmol) were refluxed in benzene (4.8 mL) for 2 h,
concentrated, and purified by flash column chromatography (silica gel,
95/5 hexanes/EtOAc) to afford 11-Dien-Precursor-1 as a yellow solid
(1.22 g, 91% yield). Mp: 44−46 °C. IR (ZnSe, thin film): 2139 (C
C), 1710 (CO) cm−1. 1H NMR (400 MHz, CDCl3): δ 0.24 (s, 9H,
CH). 13C{1H} NMR (100 MHz, CDCl3): δ 4.8 (CCCH3), 18.3
(CH(CH3)CH3), 18.6 (CH(CH3)CH3), 22.3 (CH2), 22.5 (CH2), 25.3
(CH2), 31.4 (CH2), 34.2 (CH(CH3)CH3), 78.7 (CH(OH)CH), 79.8
(CC), 91.0 (CC), 120.7 (CC), 129.8 (CHCH), 132.2
(CHCH), 138.3 (CC). HRMS-(EI) (m/z): [M + H]+ calcd for
C14H20O.Na, 241.1563; found, 241.1567.
(E)-4-(2-((Trimethylsilyl)ethynyl)cyclohex-1-enyl)but-3-en-2-
one (12-Dien-Precursor). 1-(Triphenylphosphoranylidene)-2-prop-
anone (640 mg, 2.01 mmol) and 7 (398 mg, 1.93 mmol) were refluxed
in toluene (1 mL) for 1.5 h, concentrated, and purified by flash column
chromatography (silica gel, 93/7 hexanes/EtOAc) to afford 12-Dien-
Precursor as a yellow solid (307 mg, 65% yield). Mp: 45−50 °C. IR
(KBr, neat): 2137 (CC), 1691 (CO) cm−1. 1H NMR (500 MHz,
CDCl3): δ 0.23 (s, 9H, TMS), 1.59−1.70 (m, 4H, 4,5-CH2), 2.20−
2.24 (m, 2H, 6-CH2), 2.30−2.35 (m, 2H, 3-CH2), 2.31 (s, 3H,
C(O)CH3), 6.10 (d, 3JHH = 16 Hz, 1H, CHCHC(O)CH3), 7.91 (d,
3JHH = 16 Hz, 1H, CHCHC(O)CH3). 13C{1H} NMR (100 MHz,
3
TMS), 1.31 (t, JHH = 7.0 Hz, 3H, CH2CH3), 1.59−1.71 (m, 4H, 4,5-
CH2), 2.20−2.26 (m, 2H, 6-CH2), 2.30−2.36 (m, 2H, 3-CH2), 4.22
(q, 3JHH = 7.0 Hz, 2H, CH2CH3), 5.88 (d, 3JHH = 16.1 Hz, 1H, CH
3
CHCO2Et), 8.06 (d, JHH = 16.1 Hz, 1H, CHCHCO2Et). 13C{1H}
NMR (100 MHz, CDCl3): δ 0.1 (TMS), 14.5 (CH2CH3), 21.9 (CH2),
22.0 (CH2), 25.0 (CH2), 31.3 (CH2), 60.4 (CH2CH3), 102.3 (CC),
104.3 (CC), 117.7 (CHCH), 127.8 (CC), 139.9 (CC),
144.2 (CHCH), 167.6 (CO2Et). HRMS-(EI) (m/z): [M + H]+
calcd for C16H24O2Si, 276.1540; found, 276.1543.
(E)-3-(2-((Trimethylsilyl)ethynyl)cyclohex-1-en-1-yl)prop-2-
en-1-ol (11-Dien-Precursor-2). Lithium aluminum hydride (103 mg,
2.71 mmol) was added to a stirred solution of 11-Dien-Precursor-1
(250 mg, 0.904 mmol) in Et2O (9 mL) at 0 °C. After it was stirred at 0
°C for 10 min, the reaction mixture was quenched by sequential
addition of H2O (0.40 mL), 1.3 M aqueous NaOH (0.80 mL), and
H2O (1.2 mL), filtered through anhydrous K2CO3, and concentrated
to afford 11-Dien-Precursor-2 as a colorless oil (209 mg, 99% yield). IR
CDCl3): δ 0.1 (TMS), 21.8 (CH2), 21.9 (CH2), 24.9 (CH2), 26.3
(CH3), 31.3 (CH2), 102.8 (CC), 104.1 (CC), 127.1 (CH
CHC(O)CH3), 128.7 (1-C), 140.2 (2-C), 143.7 (CHCHC(O)-
CH3), 199.5 (C(O)CH3). HRMS-(EI) (m/z): [M + H]+ calcd for
C15H22OSi, 246.1434; found, 246.1434.
(E)-4-(2-((Trimethylsilyl)ethynyl)cyclohex-1-enyl)but-3-en-2-
ol (12-Dien). NaBH4 (374 mg, 9.89 mmol) was added to a stirred
solution of 12-Dien-Precursor (812 mg, 3.30 mmol) in MeOH/THF
(66 mL, 1/1) at 23 °C. After 10 min of stirring at 23 °C, the reaction
mixture was diluted with saturated aqueous NH4Cl (100 mL) and
extracted with Et2O (2 × 100 mL). The organic extracts were washed
with brine (200 mL), dried over MgSO4, and concentrated to afford
12-Dien as a pale yellow oil (775 mg, 95% yield). IR (NaCl, neat):
3345 (OH), 2135 (CC) cm−1. 1H NMR (400 MHz, CDCl3): δ 0.21
(s, 9H, TMS), 1.32 (d, 3JHH = 7 Hz, 3H, CH3), 1.50−1.68 (m, 5H, 4,5-
1
(ZnSe, neat): 3332 (OH), 2134 (CC) cm−1. H NMR (400 MHz,
CDCl3): δ 0.21 (s, 9H, TMS), 1.35 (bs, 1H, OH), 1.56−1.70 (m, 4H,
3
4,5-CH2), 2.20−2.30 (m, 4H, 3,6-CH2), 4.25 (d, JHH = 6.0 Hz, 2H,
3
3
CH2OH), 5.90 (dt, JHH = 15.6 Hz, JHH = 6.0 Hz, 1H, CH
CHCH2), 7.00 (d, JHH = 15.6 Hz, 1H, CHCHCH2). 13C{1H}
3
NMR (100 MHz, CDCl3): δ 0.3 (TMS), 22.1 (CH2), 22.4 (CH2),
25.3 (CH2), 30.8 (CH2), 64.3 (CH2OH), 99.5 (CC), 105.3 (C
C), 120.2 (CC), 128.2 (CHCH), 132.0 (CHCH), 140.9 (C
I
DOI: 10.1021/acs.organomet.7b00679
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
3
CH2, OH), 2.19−2.28 (m, 4H, 3,6-CH2), 4.41 (p, JHH = 7 Hz, 1H,
(CpCH3), 100.9 (CAr), 101.6 (CAr), 108.8 (CAr). HRMS-(EI) (m/z):
[M + H]+ calcd for C25H38ORuSi.F6P, 484.1730; found, 484.1734.
(η5-1-Trifluoromethyl-2,3,4,5-tetramethylcyclopentadienyl)-
(η6-6-(1-hydroxyethyl)-7-trimethylsilyltetralinyl)ruthenium(II)
Hexafluorophosphate (12-Cp‡). Ruthenium complex 1-Cp‡ (100
mg, 180 μmol) was added to a solution of 12-Ene (50 mg, 200 μmol)
in acetone/THF (10 mL, 1/1) in the glovebox. The mixture was
allowed to react for 60 min and then concentrated under vacuum. The
residue was dissolved in a minimal amount of methylene chloride, and
then the ruthenium complexes were precipitated by addition of Et2O.
The precipitate was collected on a fine frit and washed with Et2O. The
mixture of 12-Cp‡ was then purified by flash column chromatography
(silica gel, 0−2% gradient acetone/CH2Cl2) to give 12-Cp‡-maj (14.7
mg, 13% yield), and 12-Cp‡-min (15.9 mg, 14% yield) as white solids.
3
C(H)OH), 5.79 (dd, JHH = 16 Hz, 7 Hz, 1H, CHCHC(H)OH),
6.96 (d, 3JHH = 16 Hz, 1H, CHCHC(H)OH). 13C{1H} NMR (100
MHz, CDCl3): δ 0.3 (TMS), 22.1 (CH2), 22.4 (CH2), 23.4 (CH2),
25.3 (CH2), 30.7 (CH3), 69.4 (CH(OH)), 99.5 (CC), 105.3 (C
C), 120.1 (CC), 130.2 (CHCH), 133.3 (CHCH), 141.0 (C
C). HRMS-(EI) (m/z): [M + H]+ calcd for C15H24OSi, 248.1591;
found, 248.1589.
4-(2-((Trimethylsilyl)ethynyl)cyclohex-1-enyl)but-3-yn-2-ol
(12-Ene). A 1 M solution of LHMDS (9.19 mL, 9.19 mmol) in THF
was added to a stirred solution of 13-Ene (620 mg, 3.06 mmol) in
THF (31 mL) at 0 °C. After the mixture was stirred at 0 °C for 30
min, acetaldehyde (0.86 mL, 15.32 mmol) was added. After it was
stirred at 0 °C for 30 min, the reaction mixture was poured over
saturated aqueous NH4Cl (60 mL) and extracted with Et2O (60 mL).
The organic extracts were washed with brine (60 mL), dried over
MgSO4, concentrated, and purified by flash column chromatography
(silica gel, 95/5 hexanes/EtOAc) to afford 12-Ene as a yellow oil (573
mg, 76% yield). IR (NaCl, neat): 3364 (OH), 2140 (CC) cm−1. 1H
1
Data for 12-Cp‡-maj are as follows. H NMR (500 MHz, CDCl3): δ
0.43 (s, 9H, TMS), 1.54 (d, 3JHH = 6.5 Hz, 3H, CH(OH)CH3), 1.65−
1.79 (m, 4H, 2,3-CH2), 1.91 (s, 3H, Cp‡CH3), 1.94 (bs, 3H, Cp‡CH3),
1.96 (s, 3H, Cp‡CH3), 2.05 (bs, 3H, Cp‡CH3), 2.39−2.52 (m, 2H, 1,4-
2
CH2,syn), 2.69−2.75 (m, 1H, 1,4-CH2,anti), 2.84 (dt, JHH = 17.9 Hz,
3JHH = 5.6 Hz, 1H, 1,4-CH2,anti), 3.10 (d, 3JHH = 6.5 Hz, 1H, OH), 4.69
(p, 3JHH = 6.5 Hz, 1H), 5.55 (s, 1H, ArH), 6.11 (s, 1H, ArH). 13C{1H}
NMR (125 MHz, CDCl3): δ 0.69 (TMS), 10.0 (Cp‡CH3), 10.1
(Cp‡CH3), 10.4 (Cp‡CH3), 11.4 (Cp‡CH3), 21.2 (CH2), 21.5 (CH2),
3
NMR (400 MHz, CDCl3): δ 0.20 (s, 9H, TMS), 1.50 (d, JHH = 6.5
Hz, 3H, CH(OH)CH3), 1.58−1.61 (m, 4H, 4,5-CH2), 1.82 (d, 3JHH
=
6.5 Hz, 1H, OH), 2.17−2.24 (m, 4H, 3,6-CH2), 4.70 (p, 3JHH = 6.5 Hz,
1H, CH(OH)CH3). 13C{1H} NMR (100 MHz, CDCl3): δ 0.2 (TMS),
21.8 (2 × CH2), 24.6 (CH2), 29.9 (CH2), 30.0 (CH(OH)CH3), 59.0
(CH(OH)CH3), 84.7 (CC), 95.2 (CC), 98.2 (CC), 105.6
(CC), 126.7 (CC), 127.0 (CC). HRMS-(EI) (m/z): [M +
H]+ calcd for C15H22OSi, 246.1434; found, 246.1432.
25.3 (CH2), 26.5 (CH2), 26.7 (CH2), 65.7 (CH(OH)), 84.6 (q, 1JCF
=
270 Hz, CCpCF3), 84.8 (CArH), 89.3 (CArH), 92.6 (CCpCH3), 94.2
(CCpCH3), 95.4 (CArTMS), 97.4 (CCpCH3), 98.3 (CCpCH3), 103.4
1
(CArCH2), 104.32 (CArCH2), 114.2 (CArCH(OH)), 125.3 (q, JCF
=
270 Hz, CF3). 19F NMR (470 MHz, CDCl3): δ −54.40 (CF3), −72.2
(η5-Pentamethylcyclopentadienyl)(η6-6-(1-hydroxyethyl)-7-
trimethylsilyltetralinyl)ruthenium(II) Hexafluorophosphate
(12-Cp*) and (η5-Pentamethylcyclopentadienyl)(η6-6-(1-
trimethylsiloxyethyl)tetralinyl)ruthenium(II) Hexafluorophos-
phate (14-Cp*-min). Ruthenium complex 1-Cp* (50 mg, 0.099
mmol) was added to a solution of 12-Ene (29 mg, 0.119 mmol) in
THF/acetone (1/1, 2 mL) at 23 °C in a glovebox. After 30 min at 23
°C, the reaction mixture was concentrated and purified by repeated
flash column chromatography (silica gel, CH2Cl2/acetone mixtures)
followed by crystallization (CH2Cl2/Et2O) of separated fractions to
afford isolated samples of 12-Cp*-maj and isomerized 14-Cp*-min as
colorless solids. 12-Cp*-min was obtained as a mixture with 14-Cp*-
min. Only a small quantity of 14-Cp*-maj was isolated, and
spectroscopic assignments were verified by a separate arene binding
reaction (vide infra). Data for 12-Cp*-maj are as follows. Mp: 205−
(d, JPF = 712.8 Hz, PF6). HRMS-(ESI) (m/z): [M + H]+ calcd for
1
C25H36F3ORuSi.F6P, 539.1538; found, 539.1525. Data for 12-Cp‡-min
1
are as follows. H NMR (500 MHz, CDCl3): δ 0.38 (s, 9H, TMS),
3
1.55 (d, JHH = 6.4 Hz, CH(OH)CH3), 1.71 (m, 2H, 2,3-CH2), 1.82
(m, 2H, 2,3-CH2), 1.87 (s, 3H, Cp‡CH3), 1.88 (s, 3H, Cp‡CH3), 1.93
(bs, 3H, Cp‡CH3), 1.98 (bs, 3H, Cp‡CH3), 2.38−2.50 (m, 2H, 1,4-
2
3
CH2syn), 2.73 (dt, JHH = 17.4 Hz, JHH = 6.6 Hz, 1H, 1,4-CH2,anti),
2.84 (dt, 2JHH = 17.7 Hz, 3JHH = 6.5 Hz, 1H, 1,4-CH2,anti), 3.15 (bs, 1H,
3
OH), 4.58 (q, JHH = 6.4 Hz, 1H, CH(OH)CH3), 5.67 (s, 1H, ArH),
5.83 (s, 1H, ArH). 13C{1H} NMR (125 MHz, CDCl3): δ 1.5 (TMS),
10.1 (Cp‡CH3), 10.3 (Cp‡CH3), 10.4 (Cp‡CH3), 11.1 (Cp‡CH3), 21.4
(CH2), 21.5 (CH2), 21.9 (CH(OH)CH3), 25.4 (CH2), 26.2 (CH2),
66.9 (CH(OH)CH3), 84.3 (q, 36.5 Hz, CCpCF3), 86.1 (CArH), 91.8
(CArH), 92.6 (CCpCH3), 93.8 (CCpCH3), 96.6 (CArTMS), 96.7
(CCpCH3), 98.9 (CCpCH3), 103.7 (CArCH2), 104.6 (CArCH2), 110.6
207 °C dec. IR (ZnSe, thin film): 3572 (OH) cm−1. H NMR (400
MHz, CDCl3): δ 0.41 (s, 9H, TMS), 1.56 (d, JHH = 6 Hz, 3H,
1
3
(CArCH2), 125.1 (q, JCF = 272.3 Hz, CF3). 19F NMR (470 MHz,
1
CDCl3): δ −54.6 (CF3), −72.2 (d, 1JPF = 712.2 Hz, PF6) HRMS-(ESI)
(m/z): [M + H]+ calcd for C25H36F3ORuSi.F6P, 539.1538; found,
539.1537.
CH(OH)CH3), 1.60−1.69 (m, 1H, 2/3-CHsyn), 1.85 (s, 15H, Cp*),
1.75−1.93 (m, 3H, 2,3-CHanti, 2/3-CHsyn), 2.31 (dt, JHH = 17 Hz, 5.5
Hz, 1H, 1/4-CHsyn), 2.48 (dt, JHH = 17 Hz, 6 Hz, 1H, 1/4-CHsyn),
2.64−2.73 (m, 1H, 1/4-CHanti), 2.85 (dt, JHH = 17 Hz, 6 Hz, 1H, 1/4-
(η5 -Cyclopentadienyl)(η6 -6-(1-hydroxyethyl)-7-
trimethylsilyltetralinyl)ruthenium(II) Hexafluorophosphate
(12-Cp). Ruthenium complex 1-Cp (50 mg, 0.114 mmol) was added
to a solution of 12-Ene (53 mg, 0.215 mmol) and γ-terpinene (0.070
mL, 0.437 mmol) in acetone-d6 (11 mL) at 23 °C in a glovebox. After
16 h at 23 °C, the reaction mixture was concentrated and purified by
repeated flash column chromatography (silica gel, acetone/CH2Cl2
solvent mixtures) followed by crystallization (CH2Cl2/EtOAc/
hexanes) to afford a mixture of diastereomers 12-Cp-dias1 and 12-
Cp-dias2 as a colorless solid. Data for 12-Cp (mixture) are as follows.
1H NMR (300 MHz, CDCl3): δ 0.42 (s, 18H, TMS), 1.51 (d, 3JHH = 6
3
3
CHanti), 2.96 (d, JHH = 6 Hz, 1H, OH), 4.69 (p, JHH = 6 Hz, 1H,
CH(OH)CH3), 5.28 (s, 1H, ArH), 6.00 (s, 1H, ArH). 13C{1H} NMR
(100 MHz, CDCl3): δ 1.3 (TMS), 10.7 (CpCH3), 21.8 (CH2), 21.9
(CH2), 25.1, 26.2, 27.1 (2 × CH2, CH(OH)CH3), 66.3 (CH(OH)-
CH3), 84.1 (CArH), 88.9 (CArH), 92.8 (CAr), 94.9 (CpCH3), 100.7
(CAr), 102.1 (CAr), 112.5 (CAr). HRMS-(EI) (m/z): [M+H]+ calcd for
C25H39ORuSi.F6P, 485.1808; found, 485.1807. Data for 12-Cp*-min
1
are as follows. H NMR (300 MHz, CDCl3): δ 0.40 (s, 9H, TMS),
3
1.57 (d, JHH = 6.5 Hz, 3H, CH(OH)CH3), 1.60−1.69 (m, 1H, 2/3-
CHsyn), 1.83 (s, 15H, Cp*), 1.75−1.93 (m, 3H, 2,3-CHanti, 2/3-
3
3
Hz, 3H, dias1-CH(OH)CH3), 1.56 (d, JHH = 6 Hz, 3H, dias2-
CHsyn), 2.27−2.49 (m, 4H, 1,4-CHsyn), 2.66 (d, JHH = 6.5 Hz, 1H,
3
OH), 2.63−2.87 (m, 4H, 1,4-CHanti), 4.59 (p, JHH = 6.5 Hz, 1H,
CH(OH)CH3), 1.68−1.92 (m, 8H, 2,3-CH2), 2.57−2.93 (m, 9H, 1,4-
3
3
CH2, dias2-OH), 3.11 (d, JHH = 6 Hz, dias1-OH), 4.66 (p, JHH = 6
CH(OH)CH3), 5.42 (s, 1H, ArH), 5.65 (s, 1H, ArH). Data for 14-
1
Hz, 1H, dias1-CH(OH)CH3), 4.77 (p, JHH = 6 Hz, 1H, dias2-
3
Cp*-min are as follows. Mp: 245 °C dec (brown onset). H NMR
(300 MHz, CDCl3): δ 0.22 (s, 9H, TMS), 1.51 (d, 3JHH = 6.5 Hz, 3H,
CH(OTMS)CH3), 1.86 (s, 15H, Cp*), 1.63−1.91 (m, 4H, 2,3-CH2),
2.36−2.52 (m, 2H, 1,4-CHsyn), 2.69−2.84 (m, 2H, 1,4-CHanti), 4.69
(q, 3JHH = 6.5 Hz, 1H, CH(OTMS)CH3), 5.55 (d, 3JHH = 6.5 Hz, 1H,
ArH), 5.68 (s, 1H, 5-ArH), 5.81 (d, 3JHH = 6.5 Hz, 1H, ArH). 13C{1H}
NMR (100 MHz, CDCl3): δ 1.1 (TMS), 10.4 (CpCH3), 21.7 (CH2),
21.8 (CH2), 25.9, 26.3, 27.0 (2 × CH2, CH(OTMS)CH3), 67.7
(CH(OTMS)CH3), 82.8 (CArH), 83.9 (CArH), 86.8 (CArH), 94.7
CH(OH)CH3), 5.19 (s, 5H, dias2-Cp), 5.23 (s, 5H, dias1-Cp), 5.72 (s,
1H, dias1-ArH), 5.83 (s, 1H, dias2-ArH), 6.25 (s, 1H, dias2-ArH), 6.34
(s, 1H, dias1-ArH). 13C{1H} NMR (125 MHz, CDCl3): δ 0.80 (dias1-
TMS), 1.25 (dias2-TMS), 22.18 (dias2-CH2), 22.23 (dias1-CH2), 22.3
(dias2-CH2), 22.4 (dias1-CH2), 25.0 (dias2-CH(OH)CH3), 26.3 (dias1-
CH(OH)CH3), 27.9 (dias2-CH2), 28.2 (dias1-CH2), 28.3 (dias1, dias2-
CH2), 66.0 (dias1-CH(OH)CH3), 67.8 (dias2-CH(OH)CH3), 80.99
(dias2-Cp), 81.18 (dias1-Cp), 82.4 (dias1-CArH), 84.4 (dias2-CArH),
J
DOI: 10.1021/acs.organomet.7b00679
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
88.5 (dias1-CArH), 89.2 (dias2-CArH), 93.4 (dias1, dias2-CAr), 102.85
(dias1-CAr), 102.88 (dias2-CAr), 103.1 (dias1-CAr), 103.3 (dias2-CAr),
111.9 (dias2-CAr), 114.6 (dias1-CAr). HRMS-(EI) (m/z): [M + H]+
calcd for C20H29ORuSi.F6P, 409.1058; found, 409.1062.
ORCID
Ryan L. Holland: 0000-0001-9973-4781
Kim K. Baldridge: 0000-0001-7171-3487
Joseph M. O’Connor: 0000-0001-7510-3248
6-(1-(Trimethylsilyoxy)ethyl)tetralin (14-Aryl). NaBH4 (671
mg, 17.76 mmol) was added to a stirred solution of 6-acetyltetralin
(1.02 g, 5.92 mmol) in THF/MeOH (60 mL, 1/1) at 23 °C. After it
was stirred for 30 min at 23 °C, the reaction mixture was then poured
over acetone (50 mL), concentrated, diluted with H2O (150 mL), and
extracted with Et2O (150 mL). The organic extracts were washed with
brine (150 mL), dried over Na2SO4, and concentrated to afford a pale
yellow oil. Chlorotrimethylsilane (0.090 mL, 0.920 mmol) was added
to a stirred solution of the resulting oil (54 mg, 0.310 mmol) and
triethylamine (0.130 mL, 0.920 mmol) in CH2Cl2 (3.1 mL) at 23 °C.
After 2 h of stirring at 23 °C, the reaction mixture was poured over
water (3 mL) and extracted. The organic extract was washed with
water (3 mL) and brine (3 mL), dried over MgSO4, and concentrated
to afford 14-Aryl as a yellow oil (69 mg, 90% yield for second step). 1H
Present Address
§D.M.H.: Department of Chemistry and Physics, Carroll
College, 1601 N. Benton Avenue, Helena, MT 59625, United
States.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
J.M.O. gratefully acknowledges the support of the National
Science Foundation (CHE-1465079). K.K.B. thanks the
National Basic Research Program of China (2015CB856500),
the Qian Ren Scholar Program of China, and the Synergetic
Innovation Center of Chemical Science and Engineering
(Tianjin) for support of this work.
3
NMR (300 MHz, CDCl3): δ 0.08 (s, 9H, TMS), 1.41 (d, JHH = 6.5
Hz, 3H, CH(OTMS)CH3), 1.73−1.84 (m, 4H, 2,3-CH2), 2.69−2.83
3
(m, 4H, 1,4-CH2), 4.79 (q, JHH = 6.5 Hz, 1H, CH(OTMS)CH3),
6.99−7.07 (m, 3H, ArH). 13C{1H} NMR (100 MHz, CDCl3): δ 0.30
(TMS), 23.4 (2 × CH2), 27.0 (CH(OTMS)CH3), 29.2 (CH2), 29.6
(CH2), 70.6 (CH(OTMS)CH3), 122.7 (CArH), 126.1 (CArH), 129.0
(CArH), 135.7 (CAr), 136.9 (CAr), 143.6 (CAr). HRMS-(EI) (m/z): [M
+ H]+ calcd for C15H24OSi, 248.1591; found, 248.1588.
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as mixture of 14-Cp*: [M + H]+ calcd for C25H39ORuSi.F6P,
479.1841; found, 479.1832.
ASSOCIATED CONTENT
* Supporting Information
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AUTHOR INFORMATION
Corresponding Authors
*E-mail for K.K.B.: kimb@tju.edu.cn.
*E-mail for J.M.O.: jmoconnor@ucsd.edu.
■
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