Reactions of aromatic S- and O-enynes with two methyl substituents on the olefinic unit assisted by a ruthenium complex: Tandem cyclization and product selectivity

Article abstract of DOI:10.1002/asia.201301264

Ruthenium-assisted cyclizations of two enynes, HC≡CCH(OH)(C ₆H₄)X-CH₂CH=CMe₂ (X=S (1 a), O (1 b)), each of which contains two terminal methyl substituents on the olefinic parts, are explored. The reaction of 1 a in CH₂Cl₂ gives the vinylidene complex 2 a from the first cyclization and two side products, 3 a and the carbene complex 4 a with a benzothiophene ligand. The same reaction in the presence of HBF₄ affords 4 a exclusively. Air oxidation of 4 a in the presence of Et₃N readily gives an aldehyde product. In MeOH, tandem cyclizations of 1 a generate a mixture of the benzothiochromene compound 10 a and the carbene complex 7 a also with a benzothiochromene ligand. First, cyclization of 1 b likewise proceeds in CH₂Cl₂ to give 2 b. Tandem cyclization of 1 b in MeOH yields comparable products 10 b and 7 b with benzochromene moieties, yet with no other side product. The reaction of [Ru]Cl with HC≡CCH(OH)(C₆H₄)S-CH₂CH= CH₂ (1 c), which contains no methyl substituent in the olefinic part, in MeOH gives the carbene complex 15 c with an unsubstituted thiochromene by means of a C-S bond formation. Structures of 3 a and 15 c are confirmed by X-ray diffraction analysis. The presence of methyl groups of enynes 1 a and 1 b promotes sequential cyclization reactions that involve C-C bond formation through carbocationic species. Copyright

Full text of DOI:10.1002/asia.201301264

FULL PAPER
DOI: 10.1002/asia.201301264
Reactions of Aromatic S- and O-Enynes with Two Methyl Substituents on the
Olefinic Unit Assisted by a Ruthenium Complex: Tandem Cyclization and
Product Selectivity
Yi-Jhen Feng, Ying-Hsuan Lai, Ying-Chih Lin,* Shou-Ling Huang, and Yi-Hung Liu[a]
Abstract: Ruthenium-assisted cycliza-
uct. In MeOH, tandem cyclizations of
1a generate a mixture of the benzo-
thiochromene compound 10a and the
carbene complex 7a also with a benzo-
thiochromene ligand. First, cyclization
of 1b likewise proceeds in CH2Cl2 to
give 2b. Tandem cyclization of 1b in
MeOH yields comparable products
10b and 7b with benzochromene moi-
eties, yet with no other side product.
tions of two enynes, HCꢀCCH(OH)-
The reaction of [Ru]Cl with HCꢀ
À
À
N
CCH(OH)
G
O (1b)), each of which contains two
terminal methyl substituents on the
olefinic parts, are explored. The reac-
tion of 1a in CH2Cl2 gives the vinyli-
dene complex 2a from the first cycliza-
tion and two side products, 3a and the
carbene complex 4a with a benzothio-
phene ligand. The same reaction in the
presence of HBF4 affords 4a exclusive-
ly. Air oxidation of 4a in the presence
of Et3N readily gives an aldehyde prod-
which contains no methyl substituent
in the olefinic part, in MeOH gives the
carbene complex 15c with an unsubsti-
À
tuted thiochromene by means of a C S
bond formation. Structures of 3a and
15c are confirmed by X-ray diffraction
analysis. The presence of methyl
groups of enynes 1a and 1b promotes
sequential cyclization reactions that
Keywords: cyclization
· enynes ·
oxygenation · ruthenium · vinyli-
dene ligands
À
involve C C bond formation through
carbocationic species.
Introduction
have been proposed as the key intermediate in intra- and in-
À
termolecular carbon carbon bond-forming reactions be-
tween propargylic alcohols and alkenes.[12] Similar C C
À
Heterocyclic sulfur and oxygen-containing compounds such
as thiochromane and chromane derivatives attract a great
deal of interest because these compounds are commonly
found in many natural and biologically active compounds.[1]
Thiochromane derivatives are ordinary structural motifs in
pharmaceutical molecules for use in antiestrogens,[2] anti-
HIV drugs,[3] depression, schizophrenia, and Parkinsonꢀs dis-
ease.[4] Thus the development of effective strategies for the
synthesis of heterocyclic compounds remains a challenge for
modern organic synthesis.[5] Transition-metal vinylidene, ace-
tylide, and allenylidene complexes have been among the
most prominent catalytic precursors employed in organic
synthesis.[6,7] Recently, metal-catalyzed cycloisomerization of
enynes has been utilized as an efficient synthetic strategy for
a variety of carbo-[8] and heterocycles,[9,10] because of the
presence of the metal-stabilized “nonclassical” cationic in-
termediate. In addition, the metal-catalyzed cycloisomeriza-
tion of enynes often leads to various skeletal rearrange-
ments.[11] A number of ruthenium allenylidene complexes
bond-forming reactions have been reported in a ruthenium-
catalyzed intramolecular cyclization of enynes with a propar-
gylic alcohol containing heteroatoms and with various
methyl substituents on the olefinic part.[13]
Previously, we developed ruthenium-mediated skeletal re-
arrangement of 1,5-enynes, which was proposed to proceed
by means of an unusual mechanism that involves a formal
metathesis process of the terminal vinyl group with the C=C
of the vinylidene group.[14] However, ruthenium-mediated
cycloisomerizations of 1,n-enynes with a methyl group at the
terminal vinyl group produced alkoxycyclohexenes[14] and
a vinylidene complex with a cyclic ring that contains an un-
saturated vinyl group.[12e] Presumably, this vinylidene ligand
might undergo further cyclization, which was not observed.
In our previous investigation, we found a ruthenium-mediat-
ed tandem cyclization reaction of a phenyl propargylic alco-
hol, with a methyl-substituted allylic group at the ortho-posi-
tion of the aromatic ring, which afforded a tricyclic com-
pound with two newly formed six-membered rings.[8g] Quite
recently, we found that different tandem cyclization reac-
tions took place at similar enynes that contained thioether
but with an internal methyl substitutent instead of two ter-
minal methyl substituents in the olefinic group to afford an
altered tricyclic compound with a methanobenzothionine
skeleton.[9f] The reactions of enynes with various methyl
substituents on the olefinic part are significantly different
[a] Y.-J. Feng, Y.-H. Lai, Prof. Dr. Y.-C. Lin, S.-L. Huang, Y.-H. Liu
Department of Chemistry, National Taiwan University
Taipei, 106 (Taiwan)
Fax : (+886)223636359
E-mail: yclin@ntu.edu.tw
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201301264.
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Ying-Chih Lin et al.
from that of corresponding enynes with no methyl group on
the olefinic part.[8g,12e,14] As an extension of our previous
study, we explore ruthenium-mediated reactions of an aro-
matic propargylic alcohol, with a two-terminal methyl-sub-
stituent-containing allylic sulfane moiety at the ortho posi-
tion of the aromatic ring. Herein, we report our results on
the study of reactions of [Ru]Cl with aromatic sulfur- and
oxygen-enynes that contain a propargylic alcohol group.
Results and Discussion
Enyne Cyclization in CH2Cl2
Scheme 1. Reaction of 1a with [Ru]Cl in CH2Cl2.
Treatment of the aromatic propargyl alcohol 1a, which con-
tains two terminal methyl groups in the olefinic part, with
1
[Ru]Cl ([Ru]=[Cp
G
the H resonance at d=4.07 ppm, which is assigned to CgH,
with two doublet resonances at d=4.46 and 2.53 ppm, which
are assigned to CbH and the neighboring CH group of the
aliphatic ring, respectively, thus indicating formation of the
six-membered ring. The 2D HMBC NMR spectrum reveals
the presence of NH4PF6 in CH2Cl2 at room temperature af-
fords the vinylidene complex 2a together with the metalla-
cyclic complex 3a and the carbene complex 4a in a ratio of
39:55:6 (see Scheme 1). Deprotonation of 2a takes place
when the mixture is passed through an Al2O3 column to
result in the yellow acetylide complex 5a and a mixture of
3a and 4a. Reprotonation of 5a with HBF4 at 08C quantita-
tively yields 2a. The structure of 2a with a substituted thio-
chromane unit at Cb is revealed by 2D NMR spectra. For
example, the COSY NMR spectrum shows correlations of
the correlation between the triplet 13C peak at d=
2
347.84 ppm with J
N
and the CgH resonance at d=4.07 ppm.
A pathway for the cyclization reaction to yield 2a might
proceed through the formation of an allenylidene B fol-
lowed by either a direct addition of the olefinic group to the
electrophilic Cg,[12d,13b] as shown in Scheme 2. That is to say,
an intramolecular attack of the tethering olefinic portion
onto Cg of B generates the acetylide intermediate C, which
bears a cationic charge. Stability of this tertiary carbocation-
ic intermediate could significantly assist this cyclization pro-
cess. Then transfer of one terminal proton into the acetylide
ligand gives 2a. Alternatively, a concerted allenylidene-ene
pathway directly transforms B into 2a.[12a,b]
Abstract in Chinese:
For the formation of 3a and 4a, intermediate A with a p-
coordinated alkyne might play the key role. Interestingly, at
À
408C in CH2Cl2, the C C bond formation is prohibited; in-
stead, the reaction gives 3a as the major product in 86%
yield with a small amount of 4a. At higher temperature, for-
mation of A is probably favored in CH2Cl2, thus leading to
1
3a. In the H NMR spectrum of 3a, the characteristic OH
proton resonance appears as a doublet at d=3.52 ppm with
2J
ACTHUNGRTNEUNG(H,H)=8.4 Hz, which disappears upon addition of D2O.
The 31P NMR spectrum of 3a shows two broad peaks at d=
55.01 and À6.43 ppm at room temperature, which displays
two sharp peaks at 233 K. This might be due to the weak co-
ordinating ability of S atom to Ru metal.
Single crystals of 3a were obtained from CH2Cl2/hexanes.
The molecular structure was determined by X-ray diffrac-
tion analysis. An ORTEP-type view of 3a is shown in
Figure 1, and their selected bond lengths and angles are col-
À
lected in the legend below. The bond length of Ru1 C1
À
(2.053(3) ꢂ) is slightly longer than that of a typical Ru C
single bond.[15] The Ru1 S1 bond length of 2.342(1) ꢂ is
À
À
similar to other Ru S bond lengths observed for a few
arene half-sandwich complexes in which the thioether
moiety is part of a metallacycle or a mixed thioether/thiolate
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alkynyl ligand is p-coordinated
to the ruthenium center instead
of through the allenylidene or
vinylidene intermediate.[20] As
shown in Scheme 2, direct mi-
gration of PPh3 from metal
center onto Ca of the p-alkyne
ligand provides a vacant site on
the metal. Subsequent sulfur
coordination affords 3a. The
high coordination ability of the
sulfur atom to transition
metals[21,22] is attested by a varie-
ty of ruthenium complexes that
contain the S,X-chelating ligand
(X=N, O, P)[23] reported in the
literature. In a recent study, (h6-
p-cymene) ruthenium com-
plexes derived from bidentate
thiosemicarbazones were evalu-
ated for their biological activity
against breast and colorectal
carcinoma cells.[24] These com-
Scheme 2. Formation of 2a, 3a, and 4a in CH2Cl2, and 6a in MeOH.
plexes exhibited good in vitro cytotoxic activity against all
cancer cell lines.
Oxidation of 4a to Aldehyde
Interestingly, the reaction of 1a is controlled to yield 4a ex-
clusively. That is to say, the reaction of 1a with
+
[Ru]NCCH3 in the presence of NH4PF6 in CH2Cl2 gives
only 4a in 83% yield. Alternatively, in the presence of
HBF4 in MeOH at room temperature, the reaction with
[Ru]Cl also produces 4a in 78% yield. The structure of 4a
is determined by spectroscopic methods. In the 1H NMR
spectrum of 4a, the relatively downfield triplet resonance at
d=14.92 ppm with 3J
ACTHNUTRGNE(UNG P,H)=11.2 Hz is assigned to
Figure 1. ORTEP drawing of 3a. For clarity, the aryl group of PPh3 li-
gands on Ru except for the ipso-carbon atoms are omitted (thermal ellip-
soid is set at the 50% probability level). Selected bond lengths [ꢂ] and
CaH.[12e,25] As shown in Scheme 2, the reaction that yields
4a is believed to proceed by means of p coordination of the
alkynyl ligand to the metal center to give A. Cleavage of
the substituted allylic group is accompanied by a nucleophilic
attack of the S atom to give E.[26] Dehydroxylation of E
then leads to 4a. The presence of HBF4 might assist cleav-
age of the allylic group and enhances the rate of nucleophil-
ic attack, thus making 4a the only product.
À
À
À
À
angles [8]: Ru1 C1 2.053(3), Ru1 S1 2.3415(7), C1 C2 1.533(4), C2 C3
À
À
À
À
1.499(4), C1 C9 1.354(4), C11 C12 1.324(5), C2 O1 1.435(4), S1 C4
À
À
À
À
À
1.779(3), S1 C10 1.849(3), P1 C9 1.769(3); C1 Ru1 S1 91.86(8), C2
C1 Ru1 117.31(19), C9 C1 Ru1 123.0(2), C4 S1 Ru1 113.34(10), C3
C2 C1 114.2(2), C1 Ru1 P2 91.87(3), P2 Ru1 S1 87.97(3).
À
À
À
À
À
À
À
À
À
À
À
chelating ligand.[16,17] In such complexes Ru S bond lengths
A recent study by our group revealed that a metal car-
bene complex with a highly conjugated ring system might be
oxidized in the presence of amines in air to yield alde-
hyde.[25] Also with a highly conjugated ring structure, 4a un-
dergoes an oxidation reaction in air in the presence of an
excess amount of NEt3 in CH3CN at ambient temperature
to afford 2-benzothiophenecarbaldehyde 13a in 80% yield
(see Scheme 3). In the absence of NEt3, no aldehyde was
obtained even under an oxygen atmosphere. Compound 13a
À
À
À
usually range within 2.30–2.34 ꢂ. The C11 C12 and C1 C9
bond lengths of 1.324(5) and 1.354(4) ꢂ are in the range of
values for a regular double bond. The addition of a PPh3
À
group at C9 is clearly seen. The C2 O1 bond length of
À
1.435(4) ꢂ is a typical C O single bond of a hydroxyl
group.[12e]
Even though the electrophilic Ca of an allenylidene or
a vinylidene ligand is susceptible to attack[18] by a nucleo-
phile such as phosphine,[19] the presence of both the terminal
alkynyl hydrogen and the hydroxyl groups on 3a indicates
that nucleophilic attack of PPh3 should take place while the
has been used as
a precursor for the synthesis of
dihydrofuroACTHNUGTRNEUNG[3,4-c] pyridinones and shows inhibition of the
cytolytic effects of the lymphocyte toxin perforin.[27]
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Scheme 3. Oxidation of 4a to aldehyde.
The proposed pathway for the oxygenation is shown in
Scheme 3.[25] Dissociation of a PPh3 ligand provides a vacant
site for coordination of O2 to give F.[28] The promoter NEt3
or dissociated PPh3 is then treated with the activated oxygen
to give ONEt3 or OPPh3 and a metal oxo/carbene com-
plex.[29] Coupling of two ligands, induced by the incoming
PPh3 yields G,[30] which generates aldehyde 13a in good
yield.
Scheme 4. Tandem cyclization of 1a in MeOH.
Distribution of products for the reaction of 1a in MeOH
depends on the reaction temperature. The reaction at 08C
failed to give the desired products. At room temperature,
the reaction affords 7a (31% yield) together with a mixture
of 3a, 4a, and a new vinylidene complex 6a in a ratio of
33:28:28:11. The structure of 6a bears resemblance to 2a.
Presumably, addition of a methanol molecule to C generates
6a in MeOH (see Scheme 2). Deprotonation of 6a yields
the yellow acetylide complex 8a. The reaction of 1a in
MeOH at 408C for 1 day afforded 9a with benzothiochro-
mene, a precursor for 10a, in 14% yield, in addition to 3a,
4a, and 7a. The ratio of 9a/3a/4a/7a is 9:41:28:22. The reac-
tion at 408C for 3 days leads to the organic product 10a by
protonation of 9a, along with 3a, 4a, and 7a. As was men-
tioned above, the reaction in MeOH at 608C for 1 day gave
10a in 37% yield. Conducting the reaction at a higher tem-
perature in MeOH seems to promote tandem cyclization.
Similarly, the reaction of 1a with [Ru]Cl in EtOH at 608C
also afforded 3a, 7a, and 10a’ with an ethoxy group.
Both 7a and 9a are formed through 2a. As shown in
Scheme 4, the second cyclization is believed to proceed by
nucleophilic addition of the olefinic moiety to Ca of the vi-
nylidene ligand, thereby affording the intermediate H,
which contains a cationic charge on the tertiary carbon. Sub-
sequent proton migration generates 7a. Alternatively, the
addition of a methoxide group at the tertiary carbocation of
H gives 9a. Experimental results from deuterium-labeling
experiments are consistent with this pathway. The reaction
of 1a in MeOD affords 7a–d, with deuteration at the Cb
Tandem Cyclization in MeOH
Previously, tandem cyclizations of all-carbon-chain aromatic
enynes[8g] with methyl groups on the olefinic part in CHCl3/
MeOH were found to proceed through vinylidene inter-
mediates that contain unsaturated olefinic groups on the
ligand. Complex 2a also has a tethering olefinic group on
the vinylidene ligand, and is expected to show an additional
cyclization reaction, which is indeed observed when the re-
action is carried out in alcohol. Treatment of 1a with [Ru]Cl
in the presence of KPF6 in MeOH at 608C affords the car-
bene complexes 7a and 10a, in addition to 3a, in a ratio of
16:63:21 (see Scheme 4). Treatment of 2a in MeOH at 608C
also affords 7a and 10a. Two products, 7a and 10a, which
have different tetrahydrobenzothiochromene units, were
characterized by spectroscopic methods. For 7a, the HMBC
1
NMR spectrum shows correlations between the singlet H
peak at d=7.22 ppm assigned to =CH with three 13C reso-
nances at d=62.86, 39.48, and 23.78 ppm assigned to the
methylene, bridgehead CH, and methyl carbon atoms, there-
À
by revealing the C C bond formation. For 10a, the COSY
NMR spectrum shows correlations of the multiplet reso-
nance at d=5.58 ppm, which is assigned to one of two ole-
finic =CH, with that of the next methylene group. Interest-
ingly, aromatization occurs when 7a is passed through a neu-
tral Al2O3 column to give the yellow product 11a with two
aromatic rings (see Scheme 4). Two bridgehead CH resonan-
1
methylene group, as indicated by the absence of the H sig-
nals at d=3.86/2.20 ppm. Complexes 7a and 9a are not in-
terconvertible, since the attempted reaction of 7a with
MeOH in the presence of NaOMe fails to give 9a.
1
ces of 7a disappear in the H NMR spectrum of 11a. When
À
11a is treated with HCl, cleavage of the M C bond gives
12a in 86% yield. Two singlet peaks at d=3.84 and
1
2.43 ppm in the H NMR spectrum of 12a are assigned to
aliphatic CH2 and Me groups, respectively.
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Oxygen Analogue of 1a
The ruthenium-induced cyclization reaction of 1b gives
fewer products, which is most likely due to the relatively
poor coordinating ability of oxygen. Treatment of the aro-
matic enyne 1b, an oxygen analogue of 1a, with [Ru]Cl in
CH2Cl2 affords the analogous vinylidene complex 2b and
the phosphonium acetylide complex 14b in a ratio of 1.5:1
(see Scheme 5). The reaction in the presence of an excess
Scheme 6. Reaction of 1c with [Ru]Cl.
Scheme 5. Reactions of 1b with [Ru]Cl.
Figure 2. ORTEP drawing of 15c. For clarity, the aryl group of the PPh3
ligands on Ru except for the ipso-carbon atoms are omitted (thermal el-
lipsoid is set at the 50% probability level). Selected bond lengths [ꢂ]
amount of free phosphine gives only 14b in 94% yield.[31]
Deprotonation of 2b yields the acetylide complex 5b. The
reactions of 1b with [Ru]Cl in MeOH and EtOH also afford
10b and 10b’, respectively, in addition to 7b. This tandem
cyclization of 1b yields no other side product.
Formation of similar fused cyclic compounds has been re-
ported but in two separate steps.[13] An Ru-catalyzed cycliza-
tion by means of an allenylidene-ene process in the first
step is followed by a Pt-catalyzed cycloisomerization in the
second step. But in our case, tandem cyclizations readily
take place in methanol.
À
À
À
À
and angles [8]: Ru1 C1 2.015(2), C1 C2 1.425(3), C2 C3 1.354(3), C3
À
À
À
À
C4 1.426(3), S1 C1 1.719(2), S1 C9 1.745(2); Ru1 C1 C2 128.56(16),
À
À
À
À
À
À
À
Ru1 C1 S1 116.13(12), C2 C1 S1 115.32(16), C1 C2 C3 129.1(2), C1
À
S1 C9 108.77(11).
Single crystals were obtained by slow evaporation of a so-
lution of 15c in CH2Cl2/hexanes. An ORTEP-type view of
À
15c is shown in Figure 2. The Ru1 C1 bond length of
À
2.015(2) ꢂ is similar to the Ru C bond length of 2.065(7) ꢂ
À
found
for
[Cp*Ru{C(SCH2CH2 CH3)CH=CPh}(CO)-
(PMeiPr2)]+,[32] but is longer than that of a six-membered
Enynes with No Methyl Group
cyclic oxocarbene complex [CpRuACHTUGNRTENNN(GU =C5H8O)ACHTUNRTGEGN(NNU dppe)]ACHTUNGTRENNUNG[PF6]
To study the effect of the methyl substituent on the olefinic
group, we prepared the aromatic enyne 1c, which contains
an analogous olefinic chain similar to 1a but has no methyl
group. As shown in Scheme 6, treatment of 1c with [Ru]Cl
in the presence of KPF6 in MeOH at 258C afforded 15c as
the only isolable product. Nucleophilic attack of S onto Ca
was accompanied by cleavage of the S-allylic bond. No
(dppe=1,2-bis(diphenylphosphino)ethane) (1.938 ꢂ).[33]
À
The C2 C3 bond length of 1.354(3) ꢂ is in the range of
a typical double bond,[32] probably due to the conjugated
system of the ring structure. Formation of 15c most likely
proceeds by means of the g-hydroxyvinylidene intermediate
I, followed by a nucleophilic attack of the sulfur atom to Ca
to give J, accompanied by the cleavage of the allylic group
(see Scheme 6). Dehydroxylation of J then leads to 15c.
Unlike 1a, which shows reactivity of cyclization to result in
À
product with a formed C C bond was obtained. The struc-
ture of 15c was determined by spectroscopic methods and
was fully characterized by X-ray diffraction analysis. In the
COSY NMR spectrum, the characteristic doublet resonance
at d=7.87 ppm assigned to CbH shows correlation with
a multiplet resonance at d=7.05 ppm assigned to CgH. In
À
a C C bond formation, 1c displays cyclization that involves
À
a C S bond formation.
For the cyclization of 1a, the stability of the tertiary car-
bocation from the presence of two methyl groups should
play the key role in promoting the reaction. The regioselec-
tivities of sulfur attacks on the triple bonds for 1a and 1c
are quite different. Here the S attack at Ca in 1c indicates
the 2D HMBC NMR spectrum, the triplet peak at d=
2
247.10 ppm with J
(C,P)=13.1 Hz, which is assigned to Ca,
1
shows correlations with the H resonances of CbH and CgH.
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quenched with saturated aqueous NH4Cl solution and extracted with di-
ethyl ether (3ꢃ10 mL). The combined organic layer was washed with
brine, dried over MgSO4, and evaporated to give the crude product,
which was purified by flash chromatography on a silica gel column (hex-
anes/ethyl acetate (EA) 9:1) to give S1 (4.26 g, 88% yield). 1H NMR
intermediacy of a vinylidene or allenylidene ligand, whereas
the S attack at Cb in 1a that leads to 4a points to the pres-
ence of p coordination of the alkynyl ligand. Lack of methyl
substituents in 1c should enhance the rate of formation of
the vinylidene ligand, possibly owing to the smaller steric
effect. Unlike 4a, complex 15c is stable and no air oxidation
was observed.
(400.1 MHz, CDCl3): d=7.69 (dd, 3J
1H; Ph), 7.44 (dd, 3J(H,H)=7.3 Hz, 4J
(H,H)=1.5 Hz, 1H; Ph), 7.28 (m,
2H; Ph), 5.96 (s, 1H; CH), 5.28 (m, 1H; =CH), 3.52 (d, JACTHNUGNRTE(NUG H,H)=7.9 Hz,
(H,H)=7.4 Hz, 4J
ACHUTGTNRENNUG ACHUTTGNREN(NUGN H,H)=1.8 Hz,
A
ACHTUNGTRENNUNG
3
2H; CH2), 2.97 (br, 1H; OH), 1.69 (s, 3H; Me), 1.45 (s, 3H; Me),
0.19 ppm (s, 9H; Me3Si); 13C NMR (100.6 MHz, CDCl3): d=142.06 (Ph),
137.04 (=C(Me)2), 134.23, 133.54, 128.68, 127.70, 127.66 (Ph), 119.24 (=
CH), 105.04 (ꢀC), 91.55 (ꢀC), 63.23 (CH), 34.00 (CH2), 25.65 (Me),
17.55 (Me), À0.14 ppm (Me3Si).
Conclusion
Bu4NF (1m solution in THF, 19.7 mL, 19.7 mmol) was added to a solution
of S1 (3.0 g, 9.9 mmol) in THF (10 mL) at room temperature. After 4 h
the reaction was extracted with diethyl ether. The combined organic
layer was washed with brine, dried over MgSO4, and subjected to flash
column chromatography over silica gel eluting with a mixture of 9:1 hex-
anes/EA to give 1a (2.16 g, 94% yield). 1H NMR (400.1 MHz, CDCl3):
d=7.70 (m, 1H; Ph), 7.44 (m, 1H; Ph), 7.28 (m, 2H; Ph), 5.96 (s, 1H;
Tandem cyclization of the aromatic O-containing enyne 1b
to cleanly yield 7b and 10b with benzochromene groups is
induced by [Ru]Cl in MeOH. The reaction proceeds through
a first cyclization to give the vinylidene complex 2b, which
is isolated for the reaction in CH2Cl2, and in MeOH the
second cyclization proceeds to give final products. A similar
reaction of S-containing enyne 1a yields analogous benzo-
thiochromene products 7a, 10a, and other side products 3a
and 4a. The formation of 3a and 4a is believed to proceed
through a p-coordinated alkyne intermediate instead of the
vinylidene species. For 1a, the reaction conditions can be
adjusted to yield exclusively 4a, which is oxidized by O2 in
the presence of Et3N to give an aldehyde product. The pres-
ence of methyl substituents on the olefinic part of these
enynes promotes their cyclization reactions. Therefore the
reaction of enyne 1c, which has no methyl group in the ole-
finic part, gives nucleophilic addition of S onto Ca accompa-
CH), 5.28 (m, 1H; =CH), 3.53 (d, 3J
1H; OH), 2.65 (d, 3J
ACHTUNGRTEN(NGNU H,H)=7.9 Hz, 2H; CH2), 2.97 (br,
A
1.48 ppm (s, 3H; Me); 13C NMR (100.6 MHz, CDCl3): d=141.45 (Ph),
137.21 (=C(Me)2), 134.31, 133.14, 128.90, 127.63, 127.47 (Ph), 119.06 (=
CH2), 83.39 (ꢀC), 74.94 (ꢀCH), 62.64 (CH), 33.97 (CH2), 25.66 (Me),
17.57 ppm (Me).
Synthesis of 2a and 5a
A mixture of [Ru]Cl (300 mg, 0.41 mmol), 1a (143 mg, 0.62 mmol), and
NH4PF6 (167.0 mg, 1.03 mmol) in CH2Cl2 (40 mL) was stirred at ambient
temperature for 1 day. The solvent was removed under vacuum, and
CH2Cl2 was used to extract the product. The crude mixture was filtered
through Celite to remove the insoluble precipitates. The filtrate was con-
centrated to approximately 5 mL and was added to a stirred diethyl ether
(60 mL) to produce olive-colored precipitates. The powder was collected,
washed with diethyl ether, and dried under vacuum to give a mixture of
2a, 3a, and 4a. The mixture was dissolved in CH2Cl2 and was passed
through an acidic Al2O3 column eluted with hexanes/diethyl ether/
CH2Cl2. Collection of the yellow band followed by drying under vacuum
resulted in 5a (278 mg, 75% yield). 1H NMR (400.1 MHz, C6D6): d=
À
nied by the cleavage of a C S bond of the allylic group to
yield complex 15c with a six-membered cyclic thiocarbene
ligand.
7.61–6.88 (m, Ph), 5.12 (s, 1H; =CH), 5.03 (s, 1H; =CH), 4.37 (s, 5H;
Experimental Section
3
Cp), 4.29 (s, 1H; CgH), 4.11 (t, J
N
A
ACHTUNGERTN(NUNG H,H)=11.4 Hz, 1H; CH),
General Procedures
The manipulations were performed under an atmosphere of dry nitrogen
by using vacuum-line and standard Schlenk techniques. Solvents were
dried by standard methods and distilled under nitrogen before use. The
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
ruthenium complexes [CpACHTNUTGRNEUNG
(PPh3)2RuCl],[34] 1b,[13] and 1c[9f] were prepared
PPh3); elemental analysis calcd (%) for C55H48P2RuS: C 73.07, H 5.35;
found: C 73.36, H 5.47; ESI-MS: m/z: 905.21 [M+1]+.
by following the methods reported in the literature. The C and H analy-
ses and X-ray diffraction studies were carried out at the Regional Center
of Analytical Instruments at National Taiwan University. Mass spectra
were recorded with LCQ Advantage (ESI) and Finnigan MAT 95S (EI)
mass spectrometers. NMR spectra were recorded with Bruker AvanceIII
400 or DMX-500 FT-NMR spectrometers at room temperature (unless
stated otherwise). 1H and 13C NMR spectra were obtained in CDCl3 and
CD2Cl2 at ambient temperature, and chemical shifts are expressed in
parts per million. Proton chemical shifts are referenced to d=7.26
(CDCl3), 5.32 (CD2Cl2), 7.15 (C6D6), and 2.05 ppm ([D6]acetone). Carbon
chemical shifts are referenced to d=77.1 (CDCl3), 53.92 (CD2Cl2), 127.69
(C6D6), and 205.36 and 28.99 ppm ([D6]acetone). The 31P NMR spectra
were measured relative to external 85% phosphoric acid. Both 13C and
31P spectra were proton decoupled spectra.
A solution of HBF4·Et2O (48%, 0.02 mL, 0.11 mmol) in diethyl ether
(20 mL) was added dropwise at 08C to a stirred solution of 5a (300 mg,
0.33 mmol) in diethyl ether (10 mL). Insoluble solid precipitated immedi-
ately, but the addition was continued until no further solid was formed.
The solution was then decanted, and the pink solid was washed with di-
ethyl ether and dried under vacuum to yield 2a (225 mg, 75% yield).
1H NMR (400.1 MHz, CD2Cl2): d=7.43–6.50 (m; Ph), 5.09 (s, 1H; =
CH2), 5.00 (s, 5H; Cp), 4.84 (s, 1H; =CH2), 4.43 (d, 2J
1H; CbH), 3.99 (d, 2J(H,H)=6.6 Hz, 1H; CgH), 3.28 (t, 2J
12.1 Hz, 1H; CH2), 3.00 (m, 1H; CH2), 2.51 (d, 2J
(H,H)=11.8 Hz, 1H;
CH), 1.81 ppm (s, 3H; Me); 13C NMR (125.8 MHz, CD2Cl2): d=347.55
(t, 2J
(C,P)=15.3 Hz; Ca), 145.16–124.49 (Ph, =C), 112.56 (=CH2), 112.09
(Cb), 94.59 (Cp), 44.29 (CH), 38.10 (Cg), 26.58 (CH2), 23.18 ppm (Me);
31P NMR (162.0 MHz, CDCl3): d=42.52, 40.28 ppm (2d, 2J
(P,P)=
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
Synthesis of 1a
26.7 Hz, PPh3); elemental analysis calcd (%) for C55H49BF4P2RuS: C
66.60, H 4.98; found: C 66.03, H 5.28; ESI-MS: m/z: 905.21 [M]+.
nBuLi (9.9 mL, 25 mmol) was added to a solution of Me3SiCCH (4.9 mL,
34 mmol) in THF (10 mL) at À788C under nitrogen. After 20 min, 2-(3-
methylbut-2-enylthio)benzaldehyde[35] (3.2 g, 16 mmol) in dry diethyl
ether (10 mL) was added. The mixture was kept at À788C for 30 min and
was allowed to warm to room temperature. Then the mixture was
Chem. Asian J. 2014, 9, 602 – 611
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Ying-Chih Lin et al.
Synthesis of 3a
(Cb), 93.71 (Cp), 76.44 (C
(Cg), 24.07 (CH2), 23.88 (Me), 23.24 ppm (Me); 31P NMR (162.0 MHz,
CDCl3): d=43.06, 40.04 ppm (2d, 2J
(P,P)=27 Hz; PPh3); elemental anal-
ACHTUNGTRNEN(UNG OMe)(Me)2), 49.03 (OMe), 46.94 (CH), 35.08
A mixture of [Ru]Cl (200 mg, 0.27 mmol), 1a (94 mg, 0.41 mmol), and
NH4PF6 (111.7 mg, 1.03 mmol) in CH2Cl2 (40 mL) was stirred at 408C for
1 day. The solvent was removed under vacuum, and CH2Cl2 was used to
extract the crude product. The mixture was filtered through Celite to
remove the insoluble precipitates. The filtrate was concentrated to ap-
proximately 5 mL and added to stirred diethyl ether (60 mL) to produce
the olive-colored precipitates. The powder was collected, washed with di-
ethyl ether, and dried under vacuum to give complex 3a (217 mg, 86%
yield). 1H NMR (500.1 MHz, CDCl3, 233 K): d=7.79–5.98 (m; Ph), 5.60
AHCTUNGTRENNUNG
ysis calcd (%) for C56H53BF4OP2RuS: C 65.69, H 5.22; found: C 65.48, H
5.13; ESI-MS: m/z: 937.23 [M]+.
Synthesis of 7a
A mixture of [Ru]Cl (200 mg, 0.27 mmol), 1a (96 mg, 0.41 mmol), and
KPF6 (126 mg, 0.69 mmol) in MeOH (40 mL) was stirred at 608C for
1 day. The crude product was processed similarly to that for 3a. The mix-
ture was collected, washed with diethyl ether, and dried under vacuum to
give a mixture of 3a (34% yield) and 7a (29% NMR spectroscopic
(d, 2J
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
(H,P)=34.7 Hz, 1H; =CHPPh3), 5.23 (s, 1H; =CH), 5.17 (d, 3J-
(H,H)=7.0 Hz, 1H; Ph), 4.79 (s, 5H; Cp), 4.75 (s, 1H; CH), 3.79 (t, 2J-
1
yield). Data of 7a: H NMR (400.2 MHz, CDCl3): d=7.80–6.62 (m; Ph, =
2
ACHTUNGTRENNUNG(H,H)=11.0 Hz, 1H; CH2), 3.49 (d, JACHTUNGTNER(NUGN H,H)=8.4 Hz, 1H; OH), 3.34 (br,
CH), 4.86 (s, 5H; Cp), 3.86 (m, 1H; CbH2), 3.01 (d, 3J
ACHTUNGTRENNUNG
1H; CH2), 1.43 (s, 3H; Me), 0.49 ppm (s, 3H; Me); 13C NMR
1H; CgH), 2.63 (d, 3J
N
ACHTUNGTRENNUNG
2
(125.8 MHz, CDCl3, 233 K): d=233.28 (t, J
A
122.50 (Ph), 117.90 (=CH), 101.96 (dd, 1J
E
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
8.3 Hz; CHPPh3), 80.82 (Cp), 76.72 (CH), 49.15 (CH2), 26.64 (Me),
16.97 ppm (Me); 31P NMR (202.5 MHz, CDCl3, 233 K): d=55.93 (s;
PPh3), À5.37 ppm (s; PPh3); single crystals of 3a were obtained from
CH2Cl2/hexanes; elemental analysis calcd (%) for C55H51F6OP3RuS: C
61.85, H 4.81; found: C 61.53, H 4.98; ESI-MS: m/z: 923.22 [M]+.
Ca), 150.61 (=CH), 150.09–124.72 (Ph), 94.97 (Cp), 62.86 (CbH2), 39.48
(CH), 38.96 (CgH), 23.78 (Me), 22.79 ppm (SCH2); 31P NMR
(162.0 MHz, CDCl3): d=44.84, 44.37 ppm (2d, 2J
ACTHNUTRGNE(UNG P,P)=28.63 Hz; PPh3);
ESI-MS: m/z: 905.21 [M]+. Pure complex 7a was not obtained.
Synthesis of 9a
Synthesis of 4a
A mixture of [Ru]Cl (300 mg, 0.41 mmol), 1a (143 mg, 0.62 mmol), and
KPF6 (189.0 mg, 1.03 mmol) in MeOH (40 mL) was stirred at 408C for
1 day. The crude was processed similarly to that for 3a. The mixture in
CH2Cl2 (5 mL) was added to stirred hexanes (60 mL) to produce the
olive-colored precipitates and yellow filtrate. The yellow filtrate was col-
lected and concentrated to approximately 15 mL at 08C to produce the
desired yellow precipitates, which were dried under vacuum to give 9a
Method A:
A mixture of [Ru]Cl (100 mg, 0.14 mmol), 1a (48 mg,
0.21 mmol), and KPF6 (63.0 mg, 0.34 mmol) in MeOH (20 mL) with
2 drops of HBF4·Et2O was stirred at ambient temperature for 1 day. The
crude product was processed similarly to that for 3a. The powder was
washed with diethyl ether and dried under vacuum to give 4a (100 mg,
+
78% yield). Method B: A mixture of [Ru]NCCH3 (200 mg, 0.23 mmol),
1a (95 mg, 0.41 mmol), and NH4PF6 (110 mg, 0.69 mmol) in CH2Cl2
(40 mL) was stirred at room temperature for 3 days. The crude mixture
was processed similarly to that for 3a. The filtrate was concentrated to
approximately 5 mL and added to a stirred diethyl ether (60 mL) to pro-
duce the olive-colored precipitates. The powder was collected, washed
with diethyl ether, and dried under vacuum to give complex 4a (186 mg,
1
(131 mg, 14% yield). H NMR (400.2 MHz, C6D6): d=7.44–6.43 (m; Ph),
4.90 (s, 1H; =CH), 4.30 (s, 5H; Cp), 3.19 (br, 1H; CH), 3.12 (s, 3H;
OMe), 2.92 (m, 2H; CH2), 2.85 (m, 2H; CH2), 2.27 (m, H; CH),
1.20 ppm (s, 3H; Me); 13C NMR (100.6 MHz, CDCl3): d=142.94 (t, 2J-
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
1
3
83% yield). H NMR (400.1 MHz, CDCl3): d=14.92 (t, JACHTNUTRGNE(NUG P,H)=11.2 Hz,
1H; CaH), 8.12–6.96 (m; Ph), 5.15 ppm (s, 5H; Cp); 13C NMR
(100.6 MHz, CDCl3): d=287.18 (Ca), 165.42–123.71 (Ph, =C), 94.68 ppm
(Cp); 31P NMR (162.0 MHz, CDCl3): d=46.06 ppm (s; PPh3); elemental
analysis calcd (%) for C50H41F6P3RuS: C 61.16, H 4.21; found: C 61.42, H
4.33; ESI-MS: m/z: 837.14 [M]+.
AHCTUNGTRENNUNG
C56H52OP2RuS: C 71.85, H 5.60; found: C 72.23, H 5.86; ESI-MS: m/z:
937.23 [M+1]+.
Synthesis of 10a
A mixture of [Ru]Cl (200 mg, 0.27 mmol), 1a (96 mg, 0.41 mmol), and
KPF6 (126 mg, 0.69 mmol) in MeOH (40 mL) was heated to 608C for
1 day. The crude product was processed similarly to that for 9a. The
yellow solution was purified by flash chromatography on a silica gel
column (hexanes/diethyl ether 9:1) to give 10a (24.7 mg, 37% yield).
1H NMR (400.1 MHz, CDCl3): d=7.13–7.03 (m, 4H; Ph), 5.54 (m, 2H; =
Synthesis of 6a and 8a
A mixture of [Ru]Cl (300 mg, 0.41 mmol), 1a (143 mg, 0.62 mmol), and
KPF6 (189.0 mg, 1.03 mmol) in MeOH (40 mL) was stirred at ambient
temperature for 1 day. The crude mixture was obtained similarly to that
for 5a. The mixture was dissolved in CH2Cl2 and was passed through an
Al2O3 column eluted with hexanes/diethyl ethers/CH2Cl2. Collection of
the first yellow band followed by drying under vacuum resulted in 8a
CH, =CH), 3.53 (br, 1H; CH), 3.24 (s, 3H; OMe), 2.89 (d, 3J
A
3
12.4 Hz, 1H; SCH2), 2.77 (t, J
(H,H)=12.0 Hz, 1H; SCH2), 2.41 (m, 1H;
(49 mg, 83% yield). 1H NMR (400.1 MHz, C6D6): d=7.67–6.57 (m; Ph),
4.18 (s, 5H; Cp), 3.91 (s, 1H; CgH), 3.79 (t, J
CH), 2.12 (m, 2H; CH2), 1.33 ppm (s, 3H; Me); 13C NMR (100.6 MHz,
CDCl3): d=135.68, 133.16, 130.83 (Ph), 130.33 (=CH), 126.57, 126.35,
124.29 (Ph), 123.65 (=CH), 75.01 (C), 48.34 (OMe), 40.48 (CH), 39.59
(CH), 34.33 (CH2), 22.79 (CH2), 21.63 ppm (Me); EI-MS: m/z: 246.1078.
Pure compound 10a was not obtained.
3
(H,H)=11.5 Hz, 1H; CH2),
3.21 (s, 3H; OMe), 2.92 (d, 3J
(H,H)=11.9 Hz, 1H; CH), 1.57 (s, 3H; Me), 1.40 ppm (s, 3H; Me);
13C NMR (100.6 MHz, C6D6): d=139.82–123.20 (Ph), 109.62 (Cb), 100.30
(t, 2J
(C,P)=24.9 Hz; Ca), 84.94 (Cp), 76.96 (C(OMe)(Me)2), 48.23
(OMe), 45.57 (CH), 37.01 (Cg), 24.65 (CH2), 23.22 (Me), 23.00 ppm
(Me); 31P NMR (162.0 MHz, C6D6): d=51.95, 50.41 ppm (2d, 2J
(P,P)=
(H,H)=11.2 Hz, 1H; CH2), 2.08 (d, 3J-
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
Synthesis of 10a’
AHCTUNGTRENNUNG
Compound 10a’ (21 mg, 30% yield) was similarly prepared from a mix-
ture of [Ru]Cl (200 mg, 0.27 mmol), 1a (96 mg, 0.41 mmol), and KPF6
(126 mg, 0.69 mmol) in EtOH (40 mL) at 608C for 1 day. 1H NMR
(400.1 MHz, CDCl3): d=7.18–7.04 (m, 4H; Ph), 5.55 (m, 2H; =CH, =
37.0 Hz; PPh3); elemental analysis calcd (%) for C56H52OP2RuS: C 71.85,
H 5.06; found: C 71.98, H 5.21; ESI-MS: m/z: 937.23 [M+1]+.
Synthesis of 6a (86 mg, 80% yield) was achieved by treating 8a (98 mg,
0.10 mmol) with HBF4·Et2O (48%, 0.02 mL, 0.11 mmol) until no further
solid was formed at 08C, followed by the same purification procedure as
that for the synthesis of 2a. Data of 6a: 1H NMR (400.2 MHz, CD2Cl2):
CH), 3.56 (br, 1H; CH), 3.48 (q, 3J
1H; SCH2), 2.81 (t, 3J
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
2.12 (m, 2H; CH2), 1.33 (s, 3H; Me), 1.21 ppm (t, 3J
ACHTUNGTRENNUNG
d=7.67–6.80 (m; Ph), 6.10 (d, 2J
CbH), 4.96 (s, 5H; Cp), 4.36 (d, 2J
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
Me); 13C NMR (100.6 MHz, CDCl3): d=135.87, 133.22, 130.91 (Ph),
130.33 (=CH), 126.66, 126.41, 124.35 (Ph), 123.85 (=CH), 74.93 (C), 55.69
(OCH2), 40.93 (CH), 39.65 (CH), 34.84 (CH2), 23.01 (SCH2), 22.46 (Me),
ACHTUNGTRENNUNG(H,H)=12.1 Hz, 1H; CH2), 3.20 (s, 3H; OMe), 3.15 (m, 1H; CH2), 1.85
(m, 1H; CH), 1.35 (s, 3H; Me), 1.32 ppm (s, 3H; Me); 13C NMR
(100.6 MHz, CD2Cl2): d=348.79 (br; Ca), 139.32–124.38 (Ph), 112.14
Chem. Asian J. 2014, 9, 602 – 611
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Ying-Chih Lin et al.
16.07 ppm (Me); elemental analysis calcd (%) for C16H20OS: C 73.80, H
Synthesis of 2b and 5b
7.74; found: C 73.96, H 7.83; EI-MS: m/z: 260.1235.
Complex 14b (300 mg, 0.26 mmol) in CH2Cl2 was passed through
a column packed with neutral Al2O3 eluted with diethyl ether and EA.
Collection of the yellow band followed by drying under vacuum resulted
in a crude mixture. The crude mixture was dissolved in diethyl ether and
was passed through a neutral Al2O3 column eluted with hexanes/diethyl
ether. Collection of the yellow band followed by drying under vacuum re-
sulted in the product 5b (140 mg, 80% yield). 1H NMR (400.1 MHz,
CDCl3): d=7.79–7.38 (m; Ph), 5.01 (s, 1H; =CH), 4.80 (s, 1H; =CH),
Synthesis of 11a
The mixture of 3a and 7a was passed through a neutral Al2O3 column
eluted with diethyl ether/CH2Cl2. A yellow band and the second olive-
colored band were collected separately followed by drying under vacuum
to result in 11a (71 mg, 46%) and 3a (90 mg, 49%). Data of 11a:
1H NMR (400.2 MHz, CD2Cl2): d=7.72–6.68 (m; Ph), 4.28 (s, 5H; Cp),
3.69 (s, 2H; CH2), 1.96 ppm (s, 3H; Me); 13C NMR (100.6 MHz, CD2Cl2):
4.64 (d, 3J
OCH2), 4.18 (s, 5H; Cp), 4.12 (s, 1H; CgH), 2.60 (d, 3J
1H; CH), 2.01 ppm (s, 3H; Me); 13C NMR (100.6 MHz, CDCl3): d=
153.09–116.22 (Ph, =C), 109.88 (=CH2), 108.74 (Cb), 98.14 (t, 2J
(C,P)=
(H,H)=10.9 Hz, 1H; OCH2), 4.62 (t, 3J
ACHUTGTNRENNUG CAHTUNGTRENNUNG
d=154.62 (t, 2J
85.95 (Cp), 27.24ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
d=51.11 ppm (s; PPh3); elemental analysis calcd (%) for C55H46P2RuS: C
73.23, H 5.14; ESI-MS: m/z: 903.18 [M+1]+. Pure complex 11a was not
obtained.
ACHTUNGTRENNUNG
26.9 Hz; Ca), 85.15 (Cp), 66.16 (OCH2), 43.27 (CH), 36.05 (Cg),
22.71 ppm (Me); 31P NMR (162.0 MHz, CDCl3): d=51.45, 50.75 ppm
(2d, 2J
ACHTNUGTRNEUNG(P,P)=37.5 Hz, PPh3); elemental analysis calcd (%) for
Synthesis of 12a
C55H48OP2Ru: C 74.39, H 5.45; found: C 74.60, H 5.54; ESI-MS: m/z:
889.23 [M+1]+.
HCl (1m, 0.08 mL) was added to a solution of 11a (72 mg, 0.08 mmol) in
CHCl3 (10 mL). The resulting solution was stirred at ambient tempera-
ture for 1 day, and CH3Cl was removed under vacuum. The crude was
purified by flash chromatography on a silica gel column (hexanes/EA
A solution of HBF4·Et2O (48%, 0.02 mL, 0.11 mmol) in dry diethyl ether
(20 mL) was added dropwise at 08C to a stirred solution of 5b (140 mg,
0.16 mmol) in diethyl ether (10 mL). Insoluble solid precipitates formed
immediately, but the addition was continued until no further solid was
formed. The solution was then decanted, and the slightly orange solid
was washed with diethyl ether and dried under vacuum to yield 2b
(116 mg, 82% yield). 1H NMR (400.2 MHz, CDCl3): d=7.27–6.76 (m;
Ph), 5.09 (s, 1H; =CH2), 5.03 (s, 5H; Cp), 4.86 (s, 1H; =CH2), 4.66 (s,
1
4:1) to give 12a (14.5 mg, 86% yield). H NMR (400.1 MHz, CDCl3): d=
7.77 (d, 3J
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
(H,H)=7.6 Hz, 1H; Ph), 7.54 (d, 3J
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
7.44 (dd, 3J(H,H)=7.4 Hz, 4J
3.84 (s, 2H; SCH2), 2.43 ppm (s, 3H; Me); 13C NMR (100.6 MHz,
CDCl3): d=135.20, 134.68, 134.23, 133.58, 132.66, 129.90, 128.12, 127.42,
127.07, 126.23, 126.06, 124.08 (Ph), 27.32 (SCH2), 19.90 ppm (Me); ele-
mental analysis calcd (%) for C14H12S: C 79.20, H 5.70; found: C 78.78,
H 5.84; EI-MS: m/z: 212.0660.
1H; OCH2), 4.48 (d, 3J
4.05 (dd, 3J(H,H)=8.4 Hz, 3J
CH), 1.79 ppm (s, 3H; Me); 13C NMR (125.8 MHz, CD2Cl2): d=347.16
(t, 2J
(C,P)=15.2 Hz; Ca), 154.10–117.13 (Ph, =C), 116.08 (=CH2), 112.92
(Cb), 94.84 (Cp), 66.20 (OCH2), 43.78 (CH), 33.75 (Cg), 23.47 ppm (Me);
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Synthesis of 13a
31P NMR (162.0 MHz, CDCl3): d=42.52, 40.28 ppm (2d, 2J
ACHTUNGTRENNUNG(P,P)=
NEt3 (5 mL) and CH3CN (10 mL) in air were added to a flask that con-
tained 4a (300 mg, 0.36 mmol). The flask was opened to air, and the mix-
ture was stirred at room temperature for 1 day. The originally brown so-
lution turned into a dark solution. Then solvent was removed under
vacuum. The residue was purified by flash chromatography (silica gel,
hexanes/diethyl ether 4:1) to afford 13a (46.4 mg, 80%). 1H NMR
(400.1 MHz, CDCl3): d=10.12 (s, 1H; CHO), 8.04 (s, 1H; =CH), 7.95 (d,
26.7 Hz; PPh3); ESI-MS: m/z: 889.23 [M]+. Pure complex 2b was not ob-
tained.
Synthesis of 7b
A mixture of [Ru]Cl (400 mg, 0.55 mmol), 1b (239 mg, 1.10 mmol), and
KPF6 (203 mg, 1.10 mmol) in MeOH (30 mL) was stirred at 608C for
1 day. The crude mixture was obtained similarly to that for 14b. The fil-
trate was concentrated to approximately 5 mL and added to stirred dieth-
yl ether (60 mL) to produce the olive-colored precipitates. The powder
was collected, washed with diethyl ether, and dried under vacuum to give
3J
ACHTUNGTRENNUNG(H,H)=7.9 Hz, 1H; Ph), 7.91 (m, 1H; Ph), 7.51 (m, 1H; Ph), 7.44 ppm
(m, 1H; Ph); 13C NMR (100.6 MHz, CDCl3): d=184.65 (CH=O), 134.40
(=CH), 128.17, 126.27, 125.27, 123.34 ppm (Ph); elemental analysis calcd
(%) for C9H6OS: C 66.64, H 3.73; found: C 66.50, H 3.79; EI-MS: m/z:
162.0139.
1
7b (125 mg, 52% yield). H NMR (400.1 MHz, CDCl3): d=7.66–6.78 (m;
Ph, =CH), 4.90 (s, 5H; Cp), 4.07 (d, 3J
ACHTUNGTRENNUNG
Synthesis of 14b
(m, 1H; CbH2), 3.57 (t, 3J
A
3
A mixture of [Ru]Cl (200 mg, 0.28 mmol), 1b (119 mg, 0.55 mmol), KPF6
(76 mg, 0.41 mmol), and PPh3 (217 mg, 0.83 mmol) in MeOH (25 mL)
was stirred at ambient temperature for 1 day. The resulting yellow sol-
vent was removed under vacuum, and CH2Cl2 was used to extract the
crude product. The mixture was filtered through Celite to remove insolu-
ble precipitates. The filtrate was concentrated to approximately 5 mL and
added to a stirred diethyl ether (60 mL) to produce the yellow precipi-
tates, which were filtered and dried under vacuum to give complex 14b
(298 mg, 94% yield). 1H NMR (400.1 MHz, CDCl3): d=7.32–6.72 (m,
CbH2), 2.88 (d, J
A
(s, 3H; Me); 13C NMR (100.6 MHz, CDCl3): d=314.50 (t, 2J
ACHTUNGTRENNUNG
Ca), 153.73–116.90 (Ph), 151.98 (=CH), 94.90 (Cp), 62.68 (CbH2), 61.50
(OCH2), 39.21 (CH), 34.53 (CgH), 23.68 ppm (Me); 31P NMR
(162.0 MHz, CDCl3): d=45.08, 44.33 ppm (2d, 2J
ACTHNUTRGNE(UNG P,P)=28.74 Hz; PPh3);
ESI-MS: m/z: 889.23 [M]+. Pure complex 7b was not obtained.
Synthesis of 10b
A mixture of [Ru]Cl (500 mg, 0.69 mmol), 1b (298 mg, 1.38 mmol), and
KPF6 (190 mg, 1.30 mmol) in MeOH (50 mL) was stirred at ambient tem-
perature for 1 day. Solvent of the resulting brownish-black solution was
removed under vacuum, and CH2Cl2 was used to extract the crude prod-
uct. The mixture was filtered through Celite to removed insoluble precip-
itates. The crude mixture was processed similarly to that for 9a. The
yellow solution was purified by flash column chromatography over an
Al2O3 column by eluting with a mixture of hexanes/diethyl ether (8:1) to
give 10b (192 mg, 61%). 1H NMR (400.1 MHz, CDCl3): d=7.17 (d, 3J-
49H; Ph), 5.32 (dd, 4J
(t, 3J(H,H)=7 Hz, 1H;=CH), 4.30 (dd, 3J
8.1 Hz, 1H; OCH2), 4.22 (s, 5H; Cp), 3.72 (dd, 3J
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
(H,H)=17.7 Hz, 4J
A
U
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG(H,H)=8.1 Hz, 1H; OCH2), 1.78 (s, 1H; Me), 1.63 ppm (s, 1H; Me);
13C NMR (100.6 MHz, CDCl3): d=155.44 (Ph), 138.22 (=C(Me)2),
137.81–120.25 (Ph), 118.86 (=CH), 118.06 (Cb), 111.24 (Ph), 97.66 (d, 2J-
ACHTUNGTRENNUNG ACHTUNGTRENNUNG
(C,P)=9.2 Hz; Ca), 84.58 (Cp), 64.71 (OCH2), 33.33 (d, 1J
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
CPPh3); elemental analysis calcd (%) for C73H64F6OP4Ru: C 67.64, H
A
ACHTUNGTRENNUNG
4.98; found: C 67.55, H 5.06; ESI-MS: m/z: 1151.32 [M]+.
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
(m, 1H; CH), 2.07(m, 2H; CH2), 1.32 ppm (s, 3H; Me); 13C NMR
609 ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2014, 9, 602 – 611

www.chemasianj.org
Ying-Chih Lin et al.
(100.6 MHz, CDCl3): d=154.82 (OPh), 129.63, 127.45, 124.56, 120.52,
116.78 (Ph), 129.38 (=CH2), 123.30 (=CH2), 73.76 (C), 63.58 (OCH2),
48.30 (OMe), 38.20 (CH), 36.44 (CH), 34.35 (CH2), 21.76 ppm (Me); ele-
mental analysis calcd (%) for C15H18O2: C 78.23, H 7.88; found: C 77.86,
H 8.14; EI-MS: m/z: 230.1307.
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Synthesis of 10b’
Compound 10b’ (160 mg, 47% yield) was similarly prepared from a mix-
ture of [Ru]Cl (500 mg, 0.69 mmol), 1b (298 mg, 1.38 mmol), and KPF6
(190 mg, 1.30 mmol) in EtOH (50 mL) at 608C for 1 day. 1H NMR
(400.1 MHz, CDCl3): d=7.15 (t, 3J
(H,H)=7.6 Hz, 1H; Ph), 6.89 (t, 3J
(H,H)=8.2, 1H; Ph), 5.64 (d, 3J
(H,H)=10.1 Hz, 1H; =CH), 5.54 (m,
1H; =CH), 4.36 (m, 1H; OCH2), 3.70 (t, 2J
(H,H)=10.9 Hz, 1H; OCH2),
3.51 (m, 2H; OCH2), 3.37 (s, 1H; CH), 2.42 (m, 1H; CH), 2.08 (m, 2H;
CH2), 1.32 (s, 3H; Me), 1.98 ppm (t, 3J
(H,H)=7.0 Hz, 3H; OCH2Me);
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
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13C NMR (100.6 MHz, CDCl3): d=154.89 (OPh), 129.63, 127.47, 124.73,
120.54, 116.81 (Ph), 129.36 (=CH2), 123.47 (=CH2), 73.60 (C), 63.83
(OCH2), 55.64 (OCH2Me), 38.61 (CH), 36.49 (CH), 34.96 (CH2), 22.55
(Me), 16.00 ppm (OCH2Me); elemental analysis calcd (%) for C16H20O2:
C 78.65, H 8.25; found: C 78.34, H 8.41; EI-MS: m/z: 244.1463.
Synthesis of 15c
A mixture of [Ru]Cl (300 mg, 0.41 mmol), 1c (109 mg, 0.53 mmol), and
KPF6 (189.0 mg, 1.03 mmol) in MeOH (40 mL) was stirred at ambient
temperature for 2 days. The crude mixture was obtained similarly to that
for 3a. The crude mixture in CH2Cl2 (5 mL) was added to stirred hexanes
(60 mL) to produce the red precipitates, then filtered. The powder was
dried under vacuum to give complex 15c (348 mg, 86% yield). Spectro-
scopic data of 15c: 1H NMR (400.1 MHz, [D]acetone): d=7.87 (d, 3J-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Ca), 148.97 (Ph), 144.43 (Cb), 135.36–123.06 (Ph, Cg), 91.32 ppm (Cp);
31P NMR (162.0 MHz, CDCl3): d=44.25 ppm (s; PPh3); elemental analy-
sis calcd (%) for C50H41F6P3RuS: C 61.16, H 4.21; found: C 60.86, H 4.18;
ESI-MS: m/z: 837.14 [M]+.
X-ray Structure Determination of 3a and 15c
Single crystals of complexes 3a and 15c suitable for an X-ray diffraction
study were glued to a glass fiber and mounted on a SMART CCD dif-
fractometer. The diffraction data were collected using 3 kW sealed-tube
MoKa radiation (T=295 K). The exposure time was 5 s per frame. Sie-
mens area detector absorption (SADABS)[36] corrections were applied,
and decay was negligible. Data were processed, and the structure was
solved and refined by the SHELXTL[37] program. Hydrogen atoms were
placed geometrically using the riding model with thermal parameters set
to 1.2 times that for the atoms to which the hydrogen is attached and
1.5 times that for the methyl hydrogen atoms.
CCDC 947596 (3a) and 947597 (15c) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif.
Acknowledgements
We thank the National Science Council, Taiwan for financial support.
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Received: September 16, 2013
Published online: November 21, 2013
Chem. Asian J. 2014, 9, 602 – 611
611
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim