Multiple reactivities of dithranol towards 1-alkynyl Fischer carbene complexes (CO)5M{double bond, long}C(OEt)C{triple bond, long}CPh (M = Cr, W) - Efficient chemical synthesis of aromatic polyketides

Article abstract of DOI:10.1016/j.jorganchem.2009.05.029

Reactions of anti-psoriasis drug dithranol with 1-alkynyl Fischer carbene complexes (CO)₅M{double bond, long}C(OEt)C{triple bond, long}CPh (M = Cr, W) were investigated under controlled conditions in which triethylamine-promoted C-addition, O-addition, electrophilic aromatic substitution, and cyclization consecutively occurred at up to five positions of dithranol. A remarkable solvent effect led to selective formation of polyphenolic organic and organometallic mono- and triscarbene complexes which were efficiently demetalated to the potentially bioactive aromatic polyketides with pyridine-N-oxide. All the organic and organometallic products were characterized by methods including X-ray single crystal structural determinations. These results have revealed the novel multiple reactivities of dithranol which might be associated to its clinical side effect, providing a new synthetic methodology to functionalize dithranol for medical purposes, and chemically synthesize aromatic polyketides.

Full text of DOI:10.1016/j.jorganchem.2009.05.029

Journal of Organometallic Chemistry 694 (2009) 3058–3067
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Multiple reactivities of dithranol towards 1-alkynyl Fischer carbene complexes
(CO)5M@C(OEt)C„CPh (M = Cr, W) – Efficient chemical synthesis of aromatic
polyketides
Ning Luo a, Zhengkun Yu a,b,
*
a Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning 116023, PR China
b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Reactions of anti-psoriasis drug dithranol with 1-alkynyl Fischer carbene complexes (CO)5M
@C(OEt)C„CPh (M = Cr, W) were investigated under controlled conditions in which triethylamine-pro-
moted C-addition, O-addition, electrophilic aromatic substitution, and cyclization consecutively occurred
at up to five positions of dithranol. A remarkable solvent effect led to selective formation of polyphenolic
organic and organometallic mono- and triscarbene complexes which were efficiently demetalated to the
potentially bioactive aromatic polyketides with pyridine-N-oxide. All the organic and organometallic
products were characterized by methods including X-ray single crystal structural determinations. These
results have revealed the novel multiple reactivities of dithranol which might be associated to its clinical
side effect, providing a new synthetic methodology to functionalize dithranol for medical purposes, and
chemically synthesize aromatic polyketides.
Received 24 March 2009
Received in revised form 19 May 2009
Accepted 21 May 2009
Available online 27 May 2009
Keywords:
Fischer carbene
Dithranol
Multiple reactivity
Polyketides
Ó 2009 Elsevier B.V. All rights reserved.
Polycarbene
1. Introduction
Compounds with a functionalized backbone similar to that
of dithranol such as 1,8-dihydroxyanthracene-9,10-dione [8],
Dithranol (1,8-dihydroxy-9(10)-anthracenone) is the most
widely used therapeutic drug for treatment of psoriasis, a common
chronic inflammatory and scaling skin disease. Apart from the ther-
apeutic benefits, dithranol causes undesirable side effect such as
unpleasant inflammation of the skin surrounding the treated psori-
atic plaques [1] because it can undergo complex transformations in
the human body [2]. Much work has been directed to reduce this
clinical side effect by acylation of dithranol at its 10-position [3],
and acylation or alkylation of its 1,8-dihydroxys and/or the 9-hydro-
xy of its tautomer, i.e., 1,8,9-trihydroxyanthracene [3,4]. However,
no major advance has been achieved in this aspect, and little effort
has been made to explore the unknown reactivities of dithranol
which might be associated to this side effect [5]. Thus, chemical
insights into the new reactivities of dithranol has been strongly de-
sired to direct functionalization of dithranol for medical purposes.
Aromatic polyketides comprise an important class of polyphenols,
many of which have been applied in drug development [6]. Based
on the structural features, dithranol can be considered as a synthetic
building block for aromatic polyketides which are usually biosyn-
thesized by complex procedures (Scheme 1) [7]. To the best of our
knowledge, dithranol-based synthesis of aromatic polyketides has
never been investigated.
9-anthrones [9], and 9-substituted or 9,10-disubstituted anthra-
cenes [10] usually act as dienes to undergo Diels–Alder cycloaddi-
tion across their 9,10-positions. Although dithranol presents a
molecular structure analogous to those of polyphenols, 9-anthro-
nes, and substituted anthracenes, its multiple functionalization in
a single reaction has never been realized. Fischer carbene complexes
have been demonstrated versatile reactivities in organic synthesis
[11–15], and base-catalyzed Michael-type addition of phenols to
1-alkynyl Fischer carbene complexes has been documented [16].
C–H insertion is also common in the transformations by means of
Fischer carbene complexes [16,17]. However, addition of electron-
rich polyphenols such as sesamol and phloroglucinol to terminal
alkynes can only be realized by Pd(0)-catalyzed C–H insertion [18].
Intrigued by the potential versatile reactivities and structural fea-
tures of dithranol (2), we investigated the multiple reactivities of 2 to-
wards 1-alkynyl Fischer carbene complexes (CO)5M@C(OEt)C„CPh
(M = Cr, W) (1) under controlled conditions, and efficiently synthe-
sized novel dithranol-based aromatic polyketides for the first time.
2. Results and discussion
2.1. Reactions of 1 and 2
* Corresponding author. Address: Dalian Institute of Chemical Physics, Chinese
Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning 116023, PR China.
Tel./fax: +86 411 8437 9227.
In our initial studies, the reactions of 2 and 1 were carried out in
different molar ratios in toluene, dichloromethane, diethyl ether or
THF at ambient temperature (Eq. (1) and Table 1). No reaction
E-mail address: zkyu@dicp.ac.cn (Z.K. Yu).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.05.029

N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
3059
EnzS
O
solution may be the same as that of 9-anthrone. Thus, 3 and/or 4
were preferably formed from the reactions of 1 and 2 in nonpolar
solvent toluene, while in polar solvents CH2Cl2, Et2O, and THF, the
9-OH and/or 9-alkoxy-containing triscarbene complexes 5 and/or 6
were favorably generated when >1.0 equiv. of 1 were used. It is
obvious that the multiple reactivities of 2 towards 1 are basically
solvent- and molar ratio of 1 to 2-dependent. Hydrogen bonding
between the hydroxy and keto groups of the newly formed prod-
ucts and the electron-donating atoms of the solvent molecules of
CH2Cl2, Et2O and THF may be another factor to favor the triol tau-
tomer of 2 in the polar solvents, rendering 5 and 6 formed as the
major products. The solvent effect is so remarkable that up to five
different positions of 2 and its triol tautomer were involved in a
single reaction of 2 and 1, forming multiple-functionalized organic
and organometallic dithranol derivatives 3–6.
O
O
O
O
O
O
O
O
HO
SCoA
A
O
O
O
O
B
HO
OH
OH
O
OH
resistomycin
Scheme 1. A biosynthesis example of aromatric polyketide (resistomycin) [7].
occurred in the absence of a base such as triethylamine except that a
very unstable brown species was formed and quickly decomposed
from the reactions in THF. Using triethylamine as solvent, the reac-
tions were complicated. However, when suitable amount of trieth-
ylamine was used, the reactions of 1 and 2 smoothly proceeded in
the organic solvents. The 1:1 molar ratio reaction of 1a (M = Cr)
and 2 formed compound 3 as the major product (10–31%) via a
green intermediate which was not successfully isolated, while 2 re-
acted faster with 1b (M = W) than with 1a in all the solvents under
the same conditions, affording 3 as the only product (28–46%)
(Table 1, entries 1–4). The 2:1 molar ratio reaction of 1a and 2
formed 4a as the major product (12–35%), and the same reaction
of 1b and 2 produced both 3 (11–15%) and 4b (5–25%) as the major
products. In the 3:1 molar ratio reactions of 1 and 2, compounds 3–6
were formed in much higher total yields than in those 1:1 and 2:1
molar ratio reactions, and a remarkable solvent effect was observed
to direct formation of the products (entries 5–8). In nonpolar tolu-
ene, 4 were generated as the major products (49% for 4a, 44% for
4b) (entry 5). In the polar solvents CH2Cl2 and Et2O, the same reac-
tions underwent faster, forming one mono- and two triscarbene
complexes, i.e., 4–6, in various yields (10–30%, entries 6 and 7).
The 3:1 molar ratio reactions proceeded much faster in THF than
in other solvents, producing 4 (21–25%) and 6 (38–51%) as the major
products (entry 8). 3 was not isolated from all the 3:1 molar ratio
reactions except in that of 1b and 2 in toluene (5%, entry 5). The
5:1 molar ratio reactions of 1 and 2 underwent in a fashion similar
to those 3:1 molar ratio reactions, and the reactions in toluene affor-
ded 4 as the major products (27–32%), and the same reactions in
CH2Cl2 and THF selectively formed 6 as the major products (26–
71%) (entries 9–11).
2.2. Reaction mechanism
A reaction mechanism is proposed in Scheme 2. Dithranol coex-
ists with its triol tautomer (20) in solution. The 10-position C–H
addition of 2 to the C„C bond of 1 initiates the reaction sequence,
forming monocarbene species C which undergoes intramolecular
nucleophilic aromatic C–H addition to the electronic M@C carbene
carbon (or described as electrophilic aromatic substitution) to pro-
duce D and is followed by reductive elimination/protonation and
tautomerization to form the organic product 3. The initially-gener-
ated green intermediate species, presumably C, was gradually
decomposed to products 3–6. It was observed that only after most
of the green intermediate species was consumed, the desired prod-
ucts could be isolated in decent yields. For example, if the reaction
mixture was worked up at the time (4–6 h) when 1a or 1b was just
consumed in the 1:1 molar ratio reaction with 2 in CH2Cl2, product
3 could only be isolated in <5% yields, whereas 3 was collected in
31–38% yields after C was completely consumed (Table 1, entry 2).
These results have suggested that species C is the possible inter-
mediate to 3 and compound 3 was not generated on silica gel dur-
ing isolation by column chromatography. In the presence of
excessive amount of 1, species C undergoes C-addition to another
molecule of 1, forming biscarbene species F which is then trans-
formed to 4 via species G through an intramolecular aromatic
C–H addition and cyclization. Both 3 and 4 can not further react
with 1 under the reaction conditions, revealing that cyclization
OEt
OH
O
OH
(CO)5M
Et3N/solvent
N2, rt
+
Ph
M = Cr (1a)
W (1b)
2
EtO
M(CO)5
O
M(CO)5
M(CO)5
M(CO)5
Ph
O
OH
O
OH
ð1Þ
OH
O
(CO)5M
O
O
OH
O
O
Ph
Ph
+
Ph
+
Ph
+
OEt
OEt
EtO
Ph
EtO
Ph
(CO)5M
Ph
(CO)5M
Ph
3
4a (M = Cr)
4b ( M = W)
5a (M = Cr)
6a (M = Cr)
5b ( M = W)
6b ( M = W)
A solvent-dependent equilibrium can be established between
9-anthrone (the keto tautomer) and its 9-hydroxy tautomer in
solution, and the keto form is strongly favored in nonpolar sol-
vents, whereas hydrogen bond acceptor solvents cause the hydro-
xy form to be slightly preferred [8]. Tautomerism of dithranol in
through the 4(5),10-positions of dithranol deactivates the newly
formed polyphenolic systems. F is tautomerized to 9-hydroxy
biscarbene H which further reacts with 1 to form triscarbene spe-
cies I which is eventually cyclized to the triscarbene product 5. H
undergoes intermolecular O-addition of its 8-hydroxy to
1

3060
N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
Table 1
Reactions of 1 and 2.
at 65 °C. In all the demetalation reactions, the (CO)5M moieties were
transformed to the easily separable complexes pyridineꢀM(CO)5. The
characteristic 13C NMR signals of the M@C carbene carbons in 8, 10
and 11 were assigned by comparison with the corresponding data of
complexes4–6. The 13C resonances of the Cr@C and Cr(CO)5 moieties
appeared at the fields lower than those of their tungsten analogues
by about 27 and 20 ppm, respectively. For example, the 13C NMR sig-
nals of the three Cr@C bonds in 6a appeared at 354.1, 333.2, and
283.8 ppm, those of the two Cr@C bonds in 10a were shown at
354.3 and 283.2 ppm, respectively, while that of the remaining sin-
gle Cr@C bond in 11a was at 282.9 ppm. The reactivities of the M@C
functionalities in the demetalation reactions follows the order: M@C
in the 10-alkenyl carbene moiety > M@C in the O,O-alkyl carbene
moiety > M@C in the cyclic alkenyl carbene moiety.
Entry 1:2a Solvent
Yield (%)b (M = Cr)
Yield (%)b (M = W)
t (h)
Toluene 11
3
4a 5a 6a t (h)
3
4b 5b 6b
1
1:1
1:1
1:1
1:1
3:1
3:1
3:1
3:1
5:1
5:1
5:1
25 15
31
3.5
14
10
4
11
8
46
38
38
28
5
2
3
CH2Cl2
Et2O
24
18
4
10
14
9
4
THF
5
Toluene 39
49
7
7
44
4
5
6
7
CH2Cl2
Et2O
20
17
6
17 15 21
21 19 26
21
30 10 16
15 22 26
4
8
THF
2
51
4
25
2
38
8
9
Toluene 37
32 14 10
9
27 14
10
11
CH2Cl2
THF
19
3.5
9
4
25 33 7.5
71
12 24 26
65
8
2
4
5
Conditions: 2, 0.3 mmol; 1, 1.0–5.0 equiv.; Et3N, 0.45 mmol; solvent, 5 mL; N2
atmosphere, 0.1 MPa, 26 °C.
a
2.4. X-ray crystallographic studies
Molar ratios of 1 to 2.
b
Isolated yields.
The molecular structures of 3, 4b, 5a and 12 were further con-
firmed by X-ray crystallographic studies (Figs. 1–4, Tables 2 and 3).
Compound 3 exists in a keto-configuration in the solid state (Fig. 1)
and intramolecular hydrogen bonds (1.70 Å) are present between
the 9-keto oxygen atom and the 1,8-dihydroxy hydrogens. Com-
plex 4b features a monocarbene structure with the keto-configura-
tion of 2 remaining in the complex molecule (Fig. 2) and complex
5a presents a triscarbene structure with a pentacyclic backbone
(Fig. 3). The three Cr@C bond lengths in 5a are in the region of
1.90–2.04 Å and a longer intramolecular hydrogen bond O–Hꢀ ꢀ ꢀO
(1.86 Å) is present between the 9-OH and one of the O–C@Cr oxy-
gen atoms. Compound 12 features a triester structure which was
generated from its triscarbene precursors 6 (Fig. 4). The organic
compounds 3 and 7 present molecular structures typical of the
structural architectures of aromatic polyketides which are clini-
cally useful and usually biosynthesized via complex pathways
[7,21]. Compound 7 may also act as a versatile bioactive agent
through hydrolysis of its lactone group [22] and in fact the pentan-
gular structure of 7 is very similar to that of antitumor agents
benastatins [23]. The polyphenolic derivatives 9 and 12, and their
followed by an intramolecular O-addition of its 9-hydroxy to the 8-
O-alkenyl to generate triscarbene intermediates J and K, respec-
tively, affording the triscarbene product 6.
2.3. Oxidative demetalation of complexes 4–6
With our previously developed methodologies for demetalation
of Fischer carbene complexes [19,20], complexes 4–6 were effi-
ciently converted to their corresponding esters, i.e., 7, 9, and 12, with
pyridine-N-oxide (PNO) (Scheme 3). Complexes 4 were demetalated
to 7 in 95% yields with 1.0 equiv. of PNO. Using 1.0 equiv. of PNO at
controlled temperatures (0 °C – r.t.), the (CO)5M@C groups in the
10-alkenyl carbene moieties of 5 and 6 were first demetalated,
affording 8 and 10, respectively. Increasing temperature and using
excess of PNO (2.5 equiv.), biscarbene complexes 8 were completely
demetalated to triester 9. With 1.0 equiv. of PNO the (CO)5M@C
groups in the 8,9-O,O-alkylcarbene moieties of 10 were demetalat-
ed, producing monocarbene complexes 11 which were further
demetalated to triester 12 in 91–95% yields with 1.5 equiv. of PNO
OH
O
OH
OH
O
OH
OH
O
OH
OH
O
OH
OEt
reductive
C-H
Michael
addition
C-add.
2
(CO)5M
elimination
insertion
3
+
protonation
OH OH OH
OEt
EtO
(OC)5HM
1
Ph
Ph
EtO
Ph
(CO)5M
Ph
+ 1
C
D
E
C-add.
+ 1, C-add.
2'
M(CO)5
OEt
M(CO)5
OEt
M(CO)5
OEt
M(CO)5
M(CO)5
OEt
OH
O
OH
OH
O
OH
OH OH OH
OEt
OH OH OH
EtO
Ph
Ph
Ph
Ph
+ 1
Ph
-EtOH
4
C-H
insertion
C-add.
OEt
OEt
EtO
Ph
(CO)5M
Ph
(CO)5M
Ph
(CO)5M
Ph
I
F
G
H
+ 1
- 2EtOH
EtO
O-add.
M(CO)5
OEt
OEt Ph
M(CO)5
OEt
Ph
O
5
(CO)5M
(CO)5M
O
OH
(CO)5M
O
OH OH
O-add.
-EtOH
Ph
Ph
6
OEt
OEt
Ph
(CO)5M
Ph
J
K
Scheme 2. A proposed reaction mechanism.

N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
3061
M(CO)5
O
OH
O
O
OH
O
O
PNO (1.0 eq)
Ph
Ph
CH2Cl2, rt, 10 h
.
py
- (CO)5M
EtO
Ph
EtO
Ph
M = Cr (4a)
7, 95% from 4a
7, 95% from 4b
W (4b)
M(CO)5
M(CO)5
O
O
O
M(CO)5
M(CO)5
PNO (1.0 eq)
CH2Cl2
O
OH
O
O
OH
O
O
OH O
PNO (2.5 eq)
THF, 55 oC
0 oC- rt
Ph
Ph
Ph
Ph
Ph
Ph
5a, 0.25 h
5b, 0.5 h
8a, 0.5 h
8b, 1.0 h
OEt
OEt
OEt
O
Ph
Ph
(CO)5M
Ph
8a (M = Cr), 91%
9, 82% from 8a
M = Cr (5a)
8b ( M = W), 93%
9, 75% from 8b
W (5b)
EtO
EtO
EtO
EtO
O
M(CO)5
M(CO)5
Ph
M(CO)5
O
Ph
O
Ph
O
Ph
O
(CO)5M
(CO)5M
O
O
O
O
O
O
O
O
O
O
PNO
PNO
PNO
(1.0 eq)
(1.0 eq)
(1.5 eq)
Ph
Ph
Ph
Ph
CH2Cl2, 0 o
6a, 0.5 h
6b, 2.0 h
C
CH2Cl2, rt
10a, 0.3 h
10b, 0.8 h
THF, 65 oC
11a, 4 h
OEt
OEt
OEt
OEt
11b, 16 h
(CO)5M
Ph
O
Ph
O
Ph
O
Ph
M = Cr (6a)
W (6b)
10a (M = Cr), 87%
10b (M = W), 75%
11a (M = Cr), 95%
11b (M = W), 93%
12, 95% from 11a
12, 91% from 11b
Scheme 3. Oxidative demetalation of complexes 4–6 with PNO.
Fig. 1. Molecular structure of 3.
possible hydrolyzed forms also exhibit structures analogous to the
substructures of many natural aromatic polyketide-derived prod-
ucts or bioactive agents [24–26].
Fig. 2. Molecular structure of 4b.
3. Summary
and all chemical shift values refer to dTMS = 0.00 ppm or CDCl3
(d(1H), 7.26 ppm; d(13C), 77.16 ppm). All the melting points were
uncorrected.
In summary, solvent-dependent multiple reactivities of dithra-
nol have been unveiled. These results might be associated to the
clinic side effect of dithranol and provide a new synthetic method-
ology for functionalization of dithranol for medical purposes and
chemical synthesis of aromatic polyketides.
4.2. Synthesis and characterization of compounds 3–6
In a similar fashion, the reactions of 1 and 2 in various molar ra-
tios were carried out in toluene, dichloromethane, diethyl ether,
and THF at room temperature. The products 3–6 were isolated by
flash silica gel column chromatography and fully characterized.
4. Experimental
4.1. General considerations
OH
O
OH
8
All the manipulations of air- and/or moisture-sensitive com-
pounds were carried out under a nitrogen atmosphere using stan-
dard Schlenk techniques. Reaction solvents were dried and
distilled prior to use by the literature methods. 1H and 13C{1H}
NMR spectra were recorded on a 400 MHz NMR spectrometer
6
7
5
4
9
10
11
1
3
EtO
Ph
2

3062
N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
petroleum ether (30–60 °C)/dichloromethane as the eluent (v/v,
2:1, Rf = 0.45) to afford the organic product 3 (88 mg, 46%). Red sin-
gle crystals were obtained by recrystallization from n-pentane/
dichloromethane (v/v, 5/1) at room temperature. M.p.: 213–
215 °C. 1H NMR (CDCl3, 23 °C, 400 MHz) d 14.75 (s, 1H, OH),
13.15 (s, 1H, OH), 8.55 (d, 1H, J = 9.2 Hz), 7.46 and 7.37 (m each,
3:2H, Ph), 7.15 (d, 1H, J = 9.2 Hz), 7.06 (t, 1H), 6.78 (m, 3H), 4.25
(q, 2H, OCH2), 1.57 (t, 3H, CH3); 13C{1H}NMR (CDCl3, 23 °C,
100 MHz) d 189.76 (Cq, C@O), 169.04, 162.91, 156.32, 146.53,
144.81, 137.90, 134.12, 134.07, 129.79, 129.40, 128.86, 127.92,
120.31, 118.13, 116.77, 115.93, 115.66, 113.87, 110.48, 109.19,
64.50 (OCH2), 14.83 (CH3). HRMS calcd for C25H18O4: m/z
382.1205. Found: 382.1207.
4.2.2. A typical procedure for the 3:1 molar ratio reactions of 1 and 2 –
the 3:1 molar ratio reactions of 1 and 2 in diethyl ether
Under a nitrogen atmosphere and at ambient temperature, to a
mixture of complex 1 (1.00 mmol) and 2 (0.33 mmol) in 5 mL
diethyl ether was added triethylamine (70 lL, 0.50 mmol) with
stirring. The reaction was monitored by TLC analysis on silica gel.
A green intermediate was initially formed and then gradually
decomposed to form the products. After the green intermediate
disappeared over a period of 17 h for the reaction of 1a and 2,
and 4 h for the reaction of 1b and 2, all the volatiles were removed
under reduced pressure and the resultant residue was purified by
flash silica gel chromatography using petroleum ether
(30–60 °C)/dichloromethane (v/v, 4/1) as the eluent, affording
complexes 4, 5, and 6, respectively. In the reactions, 3 was only de-
tected and no measurable amount was formed.
Fig. 3. Molecular structure of 5a.
1''
Cr(CO)5
9
OH
O
1
8O
13
10
6
7
5
4
11 Ph
12
3
EtO
Ph
2
4.2.3. 9-(1,1,1,1,1-Pentacarbonyl-1-chroma)-3-ethoxy-6-hydroxy-
1,11-diphenyl-8-oxa-benzo[hi]chrysene-7-one (4a)
Rf = 0.50 (petroleum ether
(30–60 °C)/dichloromethane,
v/v = 2:1). Green crystals (48 mg, 21%) were obtained from recrys-
tallization in n-pentane/dichloromethane (v/v, 4/1) at ꢁ20 °C. M.p.:
170 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d 16.90 (s, 1H, OH),
8.67 (d, 1H, J = 9.6 Hz), 8.15 (s, 1H), 7.54 (m, 3H), 7.46 (m, 5H),
7.41 (m, 4H), 7.33 (d, 1H, J = 9.6 Hz), 6.93 (s, 1H), 4.35 (q, 2H,
OCH2), 1.61 (t, 3H, CH3); 13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d
291.12(Cq, Cr@C), 225.70 and 217.49 (Cq each, 1:4, trans- and
cis-CO, Cr(CO)5), 184.56 (Cq, C@O), 171.62, 162.63, 158.25,
147.87, 143.98, 141.38, 137.87, 137.53, 134.78, 133.62, 130.65,
130.14, 129.60, 129.53, 129.20, 128.57, 128.30, 127.16, 119.56,
118.86, 117.75, 115.94, 114.71, 111.10, 110.72, 64.87 (OCH2),
14.83 (CH3). Anal. Calc. for C39H22O9Cr: C, 68.22; H, 3.23. Found:
C, 68.34; H, 3.18%.
Fig. 4. Molecular structure of 12.
4.2.1. A typical procedure for the 1:1 molar ratio reactions of 1 and
2 – synthesis of 3-ethoxy-6,8-dihydroxy-1-phenyl-benzo[de]anthra-
cen-7-one (3)
Under a nitrogen atmosphere and at ambient temperature, to a
1''
mixture of complex 1b (241 mg, 0.5 mmol) and
0.5 mmol) in 5 mL toluene was added triethylamine (104
2
(114 mg,
L,
W(CO)5
l
9
OH
O
8O
13
10
0.75 mmol) with stirring. The reaction was monitored by TLC anal-
ysis on silica gel. A green intermediate was initially formed and
then gradually decomposed to form the product. After the green
intermediate disappeared over a period of 3.5 h, all the volatiles
were evaporated under reduced pressure and the resulting residue
was subject to purification by flash silica gel chromatography with
6
7
5
4
Ph
11
12
3
1
EtO
Ph
2

N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
3063
Table 2
Crystallographic data and refinement details for 3, 4b, 5a and 12.
3
4bꢀCH2Cl2
5a
12
Empirical formula
Formula weight
T (K)
C25H18O4
382.39
293(2)
C40H24Cl2O9W
903.34
293(2)
C58H28Cr3O19
1184.80
293(2)
C45 H34O8
702.72
293(2)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
Monoclinic
P2(1)/c
7.7505(12)
10.2733(17)
23.498(4)
90
98.476(3)
90
1850.6(5)
4
Monoclinic
P2(1)/c
16.7332(10)
15.8904(9)
14.3263(8)
90
109.4100(10)
90
3592.8(4)
4
Triclinic
P1
Monoclinic
P2(1)/n
11.9871(8)
11.8034(8)
25.5997(17)
90
102.5320(10)
90
3535.8(4)
4
ꢀ
12.939(8)
13.410(8)
18.779(8)
75.318(10)
76.947(9)
64.017(9)
2809(3)
a
(°)
b (°)
c
(°)
V (Å3)
Z
2
Dc (g cmꢁ3
)
1.373
0.093
1.670
3.421
1.401
0.644
1.320
0.090
l
(mmꢁ1
)
F(0 0 0)
800
1776
1200
1472
Crystal size (mm3)
h limits (°)
0.51 ꢂ 0.47 ꢂ 0.05
1.75–27.00
10 493
0.30 ꢂ 0.16 ꢂ 0.10
1.82–26.00
19 389
0.32 ꢂ 0.27 ꢂ 0.07
1.90–26.50
12 466
0.40 ꢂ 0.35 ꢂ 0.29
1.91–25.50
18 286
No. of data collected
No. of unique data
3993
7054
10 415
6562
[R(int)
]
0.1524
0.0802
0.0623
0.0371
No. of data observed with I > 2
No. of refined parameters
Goodness-of-fit (GOF) on F2
R (all data/observed data)
wR2 (all data/observed data)
r(I)
1671
272
0.790
0.1346/0.0644
0.1678/0.1426
0.290 (ꢁ0.257)
5056
441
0.990
0.0793/0.0539
0.1445/0.1332
1.524 (ꢁ0.919)
4106
723
0.878
0.1990/0.0928
0.2556/0.2082
0.747 (ꢁ0.593)
3754
500
0.930
0.0976/0.0541
0.1475/0.1308
0.309 (ꢁ0.229)
Residual qmax (e Åꢁ3
)
Table 3
Selected bond distances (Å) and angles (°) for 3, 4b, 5a and 12.
Compound 3
O(2)–C(7)
C(11)–C(18)
C(10)–C(11)–C(12)
C(12)–C(13)–C(14)
1.277(3)
1.499(3)
21.1(2)
C(10)–C(11)
C(12)–C(13)
C(11)–C(12)–C(13)
O(1)–Hꢀ ꢀ ꢀO(2)
1.397(3)
1.379(3)
C(11)–C(12)
C(13)–C(14)
121.3(2)
O(3)–Hꢀ ꢀ ꢀO(2)
1.404(3)
1.402(3)
119.6(2)
1.77(3)
1.69(2)
Complex 4b
W–C(6)
C(19)–C(20)
C(18)–C(19)–C(20)
O(8)–Hꢀ ꢀ ꢀO(7)
2.172(7)
1.402(9)
119.6(6)
1.79
O(7)–C(15)
C(20)–C(21)
C(19)–C(20)–C(21)
1.244(8)
1.394(10)
C(18)–C(19)
C(21)–C(22)
121.7(7)
1.412(9)
1.381(10)
Complex 5a
Cr(1)–C(26)
O(17)–C(29)
C(18)–C(19)
C(17)–C(18)–C(19)
C(32)–C(33)–C(34)
2.038(7)
1.331(7)
1.512(9)
121.4(6)
123.0(6)
Cr(2)–C(32)
C(16)–C(17)
2.048(7)
1.432(9)
Cr(3)–C(12)
C(17)–C(18)
1.901(11)
1.354(9)
C(24)–C(25)–C(26)
O(17)–Hꢀ ꢀ ꢀO(19)
124.7(7)
1.86
Compound 12
C(1)–O(1)
C(2)–O(2)
1.425(2)
1.370(2)
123.4(2)
C(1)–O(2)
C(9)–C(29)
C(1)–C(25)–C(26)
1.443(2)
1.498(3)
C(1)–C(25)
O(1)–C(1)–O(2)
117.3(2)
1.505(3)
109.27(16)
C(9)–C(29)–C(36)
4.2.4. 9-(1,1,1,1,1-Pentacarbonyl-1-tungsta)-3-ethoxy-6-hydroxy-
1,11-diphenyl-8-oxa-benzo[hi]chrysene-7-one (4b)
119.27, 118.02, 116.01, 114.83, 111.16, 110.80, 64.90 (OCH2),
14.85 (CH3). Anal. Calc. for C39H22O9W: C, 57.23; H, 2.71. Found:
C, 57.47; H, 2.74%.
Rf = 0.50
(petroleum
ether
(30-60 °C)/dichloromethane,
v/v = 2:1). Deep blue crystals (40 mg, 15%) were obtained by
recrystallization from n-pentane/dichloromethane (v/v, 4/1) at
ꢁ20 °C. M.p.: 200 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d
16.88 (s, 1H, OH), 8.68 (d, 1H, J = 9.6 Hz), 8.15 (s, 1H), 7.53 (m,
3H), 7.46 (m, 5H), 7.41 (m, 4H), 7.34 (d, 1H, J = 9.6 Hz), 6.93 (s,
1H), 4.35 (q, 2H, OCH2), 1.61 (t, 3H, CH3); 13C{1H}NMR (CDCl3,
23 °C, 100 MHz) d 263.92 (Cq, W@C), 205.74 and 198.48 (Cq each,
1:4, trans- and cis-CO, W(CO)5), 184.48, 171.69, 161.83, 158.34,
147.92, 143.99, 141.80, 141.24, 141.06, 134.98, 133.70, 130.69,
130.18, 129.63, 129.24, 129.19, 128.60, 128.05, 127.40, 119.66,
1''
1'''
Cr(CO)5
Cr(CO)5
2
12
3
O1 OH O13
11
14
4
10
Ph
Ph
6
5
9
7
8
OEt
4'
2'
(CO)5Cr
Ph
3'
1'

3064
N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
4.2.5. 2,12-Bis(2-(1,1,1,1,1-pentacarbonyl-1-chroma))-7-(2-ethoxy-4-
phenyl-1,1,1,1,1-pentacarbonyl-1-chroma-buta-1,3-dien-4-yl)-4,10-
diphenyl-2H,12H-1,13-dioxa-dibenzo[a,j]anthracen-14-ol (5a)
Rf = 0.60 (petroleum ether (30–60 °C)/dichloromethane,
v/v = 2:1). Brown crystals (74 mg, 19%) were obtained by recrys-
tallization from n-pentane/dichloromethane (v/v, 5/1) at ꢁ20 °C.
M.p.: 190 °C, dec. 1H NMR (CD2Cl2, 23 °C, 400 MHz) d 11.66
(s, 1H, OH), 8.57 (s, 1H), 8.30 (s, 2H), 7.72 (d, 2H, J = 9.3 Hz),
7.64 (d, 2H, J = 9.3 Hz), 7.56 (m, 10H), 7.31 (m, 3H), 7.24 (m,
2H), 4.33 (q, 2H, OCH2), 0.31 (t, 3H, CH3); 13C{1H}NMR (CD2Cl2,
23 °C, 100 MHz) d 333.56 and 285.89 (Cq each, 1:2, Cr@C, C20
and C2/C12), 224.46 and 217.09 (Cq each, 1:4, trans- and
cis-CO, C2/C12–Cr(CO)5), 223.72 and 216.39 (Cq each, 1:4, trans-
and cis-CO, C20–Cr(CO)5), 165.72, 157.52, 141.84, 139.25, 139.01,
138.85, 134.68, 133.22, 130.88, 130.49, 130.40, 129.56, 129.38,
128.28, 125.90, 125.57, 124.95, 118.46, 110.16, 76.89 (OCH2),
13.85 (CH3). Anal. Calc. for C58H28O19Cr3: C, 58.80; H, 2.38.
Found: C, 59.78; H, 2.60%.
recrystallization from n-pentane/dichloromethane (v/v, 10/1) at
ꢁ20 °C. M.p.: 175 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d 8.38
(s, 1H), 8.31 (s, 1H), 7.55–7.41(m, 15H), 7.14 (m, 5H), 5.47 and
4.49 (d each, 1:1H, J = 14.0 Hz, CH2), 5.09 and 4.96 (s and br each,
1:1H, OCH2), 3.80 and 3.27 (s and br each, 1:1H, OCH2), 1.35 and
ꢁ0.36 (s and br each, 3:3H, 2 ꢂ CH3); 13C{1H}NMR (CDCl3) d
354.07, 333.24 and 283.79 (Cq each, 1:1:1, Cr@C, C200, C20 and
C12), 224.06 and 218.13 (Cq each, 1:4, trans- and cis-CO,
C200–Cr(CO)5), 223.81 and 216.29 (Cq each, 1:4, trans- and cis-CO,
C20–Cr(CO)5), 223.71 and 216.17 (Cq each, 1:4, trans- and cis-CO,
C12–Cr(CO)5), 165.44, 148.65, 147.78, 141.66, 139.65, 139.59,
139.36, 139.02, 134.92, 132.04, 130.47, 130.29, 130.10, 129.59,
129.38, 129.24, 129.03, 128.76, 128.61, 128.44, 129.19, 127.87,
127.50, 125.68, 122.62, 119.52, 118.51, 112.59, 109.67, 108.44,
104.22, 78.25 and 76.09 (2 ꢂ OCH2), 71.22 (CH2), 14.73 and 13.59
(2 ꢂ CH3). Anal. Calc. for C60H34O20 Cr3: C, 58.55; H, 2.78. Found:
C, 58.29; H, 2.88%.
1'''
EtO
1''
1'''
2''
3
3''
W(CO)5
W(CO)5
W(CO)5
Ph
O
12
11
2
12
(CO)5W
2
1
O
O13
3
O
1
OH O13
11
1''
14
4
5
10
4
10
Ph
Ph
Ph
6
6
9
5
9
7
7
8
8
OEt
OEt
4'
4'
2'
2'
(CO)5W
Ph
(CO)5W
Ph
3'
3'
1'
1'
4.2.8. 2-(2-Ethoxy-1,1,1,1,1-pentacarbonyl-1-tungsta-1-propen-3-yl)-
7-(2-ethoxy-4-phenyl-1,1,1,1,1-pentacarbonyl-1-tungsta-buta-1,3-
dien-4-yl)-12-(1,1,1,1,1-pentacarbonyl-1-tungsta)-2,10-diphenyl-
12H-1,3,13-trioxa-dibenzo[a,kl]anthracene (6b)
4.2.6. 2,12-Bis(2-(1,1,1,1,1-pentacarbonyl-1-tungsta))-7-(2-ethoxy-4-
phenyl-1,1,1,1,1-pentacarbonyl-1-tungsta-buta-1,3-dien-4-yl)-4,10-
diphenyl-2H,12H-1,13-dioxa-dibenzo[a,j]anthracen-14-ol (5b)
Rf = 0.60 (petroleum ether (30–60 °C)/dichloromethane,
v/v = 2:1). Brown crystals (115 mg, 22%) were obtained by recrys-
tallization from n-pentane/dichloromethane (v/v, 5/1) at ꢁ20 °C.
M.p.: 200 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d 11.60 (s,
1H, OH), 8.53 (s, 1H), 8.30 (s, 2H), 7.75 (d, 2H, J = 9.6 Hz), 7.69
(d, 2H, J = 9.6 Hz), 7.59 (m, 6H), 7.56 (m, 4H), 7.33 (m, 5H),
4.15 (q, 2H, OCH2), 0.37 (t, 3H, CH3); 13C{1H}NMR (CDCl3, 23 °C,
100 MHz) d 306.82 and 258.71 (Cq each, 1:2, W@C, C20 and
C2/C12), 204.57 and 198.08 (Cq each, 1:4, trans- and cis-CO,
C2/C12–W(CO)5), 203.30 and 197.19 (Cq each, 1:4, trans- and
cis-CO, C20–W(CO)5), 164.45, 157.46, 145.90, 142.33, 142.16,
138.87, 134.88, 133.97, 133.23, 130.54, 129.68, 129.52, 129.43,
129.20, 128.02, 126.39, 125.49, 125.24, 119.04, 110.37, 79.16
(OCH2), 14.21 (CH3). Anal. Calc. for C58H28O19W3: C, 44.08; H,
1.79. Found: C, 44.06; H, 1.82%.
Rf = 0.65 (petroleum ether (30–60 °C)/dichloromethane,
v/v = 2:1). Deep green crystals (140 mg, 26%) were obtained by
recrystallization from n-pentane/dichloromethane (v/v, 10/1) at
ꢁ20 °C. M.p.: >280 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d
8.35 (s, 1H), 8.32 (s, 1H), 7.57 (m, 9H), 7.44 (m, 2H), 7.32 (d, 1H,
J = 4.0 Hz), 7.24 (m, 5H), 7.15 (s, 3H), 5.38 and 4.20 (d each, 1:1H,
J = 13.2 Hz, CH2), 4.81 and 4.57 (q each, 1:1H, OCH2), 3.60 and
3.19 (q each, 1:1H, OCH2), 1.20 and ꢁ0.45 (t each, 3:3H,
2 ꢂ CH3); 13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d 327.07, 306.73
and 257.33 (Cq each, 1:1:1, W@C, C200, C20 and C12), 204.40 and
198.99 (Cq each, 1:4, trans- and cis-CO, C200–W(CO)5), 204.02 and
197.42 (Cq each, 1:4, trans- and cis-CO, C20–W(CO)5), 203.50 and
197.11 (Cq each, 1:4, trans- and cis-CO, C12–W(CO)5), 164.24,
148.60, 147.83, 145.42, 143.14, 142.18, 139.31, 139.07, 135.06,
135.00, 131.98, 130.53, 130.43, 130.37, 130.23, 129.31, 128.88,
128.49, 127.97, 127.86, 125.91, 122.52, 119.60, 119.02, 112.63,
109.94, 108.56, 104.23, 80.67 and 78.59 (2 ꢂ OCH2), 73.54 (CH2),
14.26, 13.17. Anal. Calc. for C60H34O20W3: C, 44.31; H, 2.11. Found:
C, 44.46; H, 2.15%.
1'''
EtO
2''
3
3''
Cr(CO)5
Ph
O
12
11
(CO)5Cr
2
1
O
O13
1''
10
4
Ph
6
5
9
7
8
OEt
4.3. Oxidative demetalation of 4–6
4'
2'
(CO)5Cr
Ph
3'
1'
4.3.1. A typical procedure for oxidative demetalation of complexes 4
Complex 4a or 4b (0.20 mmol) was reacted with pyridine
N-oxide (0.20 mmol, 1.0 equiv.) in 3 mL of dichloromethane at
room temperature for 10 h. After 4 was completely consumed, all
the volatiles were removed under reduced pressure. The resultant
residue was purified by flash silical gel chromatography using
petroleum ether (30–60 °C)/diethyl ether (v/v, 2/1) as the eluent
to afford compound 7 as the product.
4.2.7. 2-(2-Ethoxy-1,1,1,1,1-pentacarbonyl-1-chroma-1-propen-3-yl)-
7-(2-ethoxy-4-phenyl-1,1,1,1,1-pentacarbonyl-1-chroma-buta-1,3-
dien-4-yl)-12-(1,1,1,1,1-pentacarbonyl-1-chroma)-2,10-diphenyl-
12H-1,3,13-trioxa-dibenzo[a,kl]anthracene (6a)
Rf = 0.65 (petroleum ether (30–60 °C)/dichloromethane,
v/v = 2:1). Deep green crystals (105 mg, 26%) were obtained by

N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
3065
(t, 3H, CH3); 13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d 284.94 (Cq,
Cr@C, C2/C12), 224.59 and 217.10 (Cq each, 1:4, trans- and cis-
CO, Cr(CO)5), 166.07 (Cq, C@O), 164.88, 158.00, 151.89, 139.01,
138.26, 134.87, 133.01, 130.68, 130.32, 129.55, 129.30, 129.25,
127.25, 125.42, 125.26, 124.76, 121.37, 118.53, 110.47, 60.48
(OCH2), 14.16 (CH3). Anal. Calc. for C53H28O15Cr2: C, 63.10; H,
2.80. Found: C, 62.73; H, 2.84%.
O
9
8
10
OH
O
1
O
6
7
5
4
11 Ph
12
13
3
EtO
Ph
2
1''
1'''
4.3.2. 3-Ethoxy-6-hydroxy-1,11-diphenyl-8-oxa-benzo[hi]chrysene-
7,9-dione (7)
W(CO)5
W(CO)5
2
12
3
O
1
OH O13
11
Rf = 0.50 (100% dichloromethane). Orange crystals (130 mg
from 4a, 95%; 130 mg from 4b, 95%) were obtained by recrystalli-
zation from n-pentane/dichloromethane (v/v, 4/1) at ꢁ20 °C. M.p.:
276–278 °C. 1H NMR (CDCl3, 23 °C, 400 MHz) d 16.48 (s, 1H, OH),
8.67 (d, 1H, J = 9.2 Hz), 7.50 (m, 3H), 7.43 (m, 3H), 7.39 (m, 4H),
7.25 (m, 2H), 7.17 (d, 1H, J = 9.2 Hz), 6.84 (s, 1H), 6.41 (s, 1H),
4.30 (q, 2H, OCH2), 1.60 (t, 3H, CH3); 13C{1H}NMR (CDCl3, 23 °C,
100 MHz) d 185.23 (Cq, C@O), 170.72 (Cq, C@O), 160.29, 157.48,
155.40, 154.68, 147.06, 144.28, 141.43, 135.42, 133.37, 130.31,
129.74, 129.52, 129.08, 129.05, 128.64, 128.30, 128.19, 125.14,
119.16, 118.02, 116.20, 116.04, 114.84, 114.66, 110.73, 110.56,
64.70 (OCH2), 14.83 (CH3). HRMS calcd for C34H22O5: 510.1467.
Found: 510.1464.
14
4
10
Ph
P
h
6
5
9
7
8
OEt
1'
3'
O
Ph
2'
4.3.5. 3-[2,12-Bis(2-(1,1,1,1,1-pentacarbonyl-1-tungsta))-4,10-
diphenyl-14-hydroxy-2H,12H-1,13-dioxa-dibenzo[a,j]anthracen-7-
yl]-3-phenyl-acrylic acid ethyl ester (8b)
Rf = 0.50 (petroleum ether
(30–60 °C)/dichloromethane,
v/v = 1:1). Brown crystals (236 mg, 93%) were obtained by recrys-
tallization from n-pentane/dichloromethane (v/v, 4/1) at ꢁ20 °C.
M.p.: >280 °C. 1H NMR (CDCl3, 23 °C, 400 MHz) d 11.60 (s, 1H,
OH), 8.29 (s, 2H), 7.74 (d, 2H, J = 9.2 Hz), 7.66 (d, 2H, J = 9.2 Hz),
7.58 (m, 10H), 7.33 (m, 5H), 7.09 (s, 1H), 3.86 (q, 2H, OCH2), 1.02
(t, 3H, CH3); 13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d 258.01 (Cq,
W@C, C2/C12), 204.69 and 198.08 (Cq each, 1:4, trans- and
cis-CO, W(CO)5), 164.85, 164.79, 157.91, 151.85, 142.36, 142.04,
138.22, 135.06, 133.21, 130.71, 130.36, 129.28, 129.20, 127.25,
125.53, 125.34, 125.00, 121.38, 119.06, 110.67, 60.50 (OCH2),
14.17 (CH3). Anal. Calc. for C53H28O15W2: C, 50.03; H, 2.22. Found:
C, 50.59; H, 2.25%.
4.3.3. A typical procedure for stepwise oxidative demetalation of
complexes 5
Complex 5a or 5b (0.20 mmol) was reacted with pyridine
N-oxide (0.20 mmol) in 3 mL of dichloromethane with stirring at
ambient temperature, and the reaction was monitored by TLC anal-
ysis on silica gel. After 5 was completely consumed within 15–
20 min, all the volatiles were removed under reduced pressure.
The resultant residue was purified by flash silica gel chromatogra-
phy using petroleum ether (30–60 °C)/dichloromethane as the elu-
ent (v/v, 1/1) to afford complex 8a or 8b. Complex 8a or 8b
(0.20 mmol) was reacted with pyridine N-oxide (0.50 mmol,
2.5 equiv.) in 3 mL of THF at 55 °C for 0.5–1.0 h. After 8 was com-
pletely consumed, all the volatiles were removed under reduced
pressure. The resultant residue was purified by flash silica gel chro-
matography using dichloromethane/diethyl ether as the eluent
(v/v, 1/1) to afford compound 9. In a similar fashion, copmplex
5a or 5b (0.20 mmol) was reacted with excess of pyridine N-oxide
(0.70 mmol, 3.5 equiv.) in 3 mL of THF at 55 °C for 0.5–1.0 h also
afforded compound 9.
O
O
2
12
3
O
1
OH O13
11
14
4
10
Ph
Ph
6
5
9
7
8
OEt
1'
3'
O
Ph
2'
1''
1'''
4.3.6. 3-(14-Hydroxy-2,12-dioxo-4,10-diphenyl-2H,12H-1,13-dioxa-
dibenzo[a,j]anthracen-7-yl)-3-phenyl-acrylic acid ethyl ester (9)
Rf = 0.50 (diethyl ether/dichloromethane, v/v = 1:1). Yellow
crystals (108 mg from 8a, 82%; 98 mg from 8b, 75%) were obtained
by recrystallization from dichloromethane/n-pentane (v/v, 1/4) at
room temperature. M.p.: >250 °C, dec. 1H NMR (CDCl3, 23 °C,
400 MHz) d 11.09 (s, 1H, OH), 7.54 (d, 2H, J = 9.3 Hz), 7.50
(m, 6H), 7.43 (m, 4H), 7.36 (d, 2H, J = 9.3 Hz), 7.30 (m, 3H), 7.25
(m, 2H), 7.00 (s, 1H), 6.47 (s, 2H), 3.80 (q, 2H, OCH2), 0.88 (t, 3H,
CH3); 13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d 165.07, 159.26,
156.88, 156.49, 154.78, 152.50, 138.75, 135.81, 132.97, 130.33,
129.77, 129.14, 129.02, 128.61, 127.28, 124.70, 124.01, 122.09,
121.35, 113.58, 113.24, 110.36, 60.25 (OCH2), 14.04 (CH3). HRMS
calcd for C43H28O7: 656.1835. Found: 656.1844.
Cr(CO)5
Cr(CO)5
2
12
3
O
1
OH O13
11
14
4
10
Ph
Ph
6
5
9
7
8
OEt
1'
3'
O
Ph
2'
4.3.4. 3-[2,12-Bis(2-(1,1,1,1,1-pentacarbonyl-1-chroma))-4,10-
diphenyl-14-hydroxy-2H,12H-1,13-dioxa-dibenzo[a,j]anthracen-7-
yl]-3-phenyl-acrylic acid ethyl ester (8a)
Rf = 0.50
(petroleum
ether (30–60 °C)/dichloromethane,
v/v = 1:1). Brown crystals (183 mg, 91%) were obtained by recrys-
tallization from n-pentane/dichloromethane (v/v, 4/1) at ꢁ20 °C.
M.p.: 185 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d 11.71 (s, 1H,
OH), 8.27 (s, 2H), 7.74 (d, 2H, J = 9.4 Hz), 7.64 (d, 2H, J = 9.4 Hz),
7.56 (m, 10H), 7.33 (m, 5H), 7.08 (s, 1H), 3.86 (q, 2H, OCH2), 1.01
4.3.7. A typical procedure for stepwise oxidative demetalation of
complexes 6
Complex 6a or 6b (0.20 mmol) was reacted with pyridine
N-oxide (0.20 mmol) in 3 mL of dichloromethane at ambient tem-

3066
N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
perature, and the reaction was monitored by TLC analysis on silica
gel. After 6 was completely consumed over a period of 0.5 (for 6a) –
2 h (for 6b), all the volatiles were removed under reduced pressure.
The resultant residue was purified by flash silica gel chromatogra-
phy using hexanes/dichloromethane as the eluent (v/v, 1/1) to af-
ford complex 10a or 10b (Rf = 0.50 (petroleum ether (30–60 °C)/
dichloromethane, v/v = 1:2) as the product. In a similar fashion,
complex 10a or 10b (0.20 mmol) was reacted with pyridine N-
oxide (0.20 mmol) in 3 mL of dichloromethane at ambient temper-
ature for 20 (for 10a) – 50 (for 10b) min. All the volatiles were
removed under reduced pressure and the resultant residue was
purified by flash silica gel chromatography using petroleum ether
(30–60 °C)/diethyl ether (v/v, 2/1) as the eluent to afford complex
11a or 11b (Rf = 0.50, 100% dichloromethane). Complex 11a or 11b
(0.20 mmol) was further reacted with pyridine N-oxide
(0.30 mmol) in 3 mL of THF at 66 °C. After 11 was completely con-
sumed over a period of 4 (for 11a) – 16 (for 11b) h, all the volatiles
were removed under reduced pressure. The resultant residue was
purified by flash silica gel chromatography using dichlorometh-
ane/diethyl ether (v/v, 1/1) as the eluent to afford triester 12
(Rf = 0.50). Treatment of complex 6 (0.20 mmol) with excess of pyr-
idine N-oxide (0.70 mmol, 3.5 equiv.) in 3 mL of THF at 66 °C (4 h
for 6a and 16 h for 6b) also afforded compound 12.
4.3.9. 3-[2-(2-Ethoxy-1,1,1,1,1-pentacarbonyl-1-tungsta-1-propen-3-
yl)-12-(1,1,1,1,1-pentacarbonyl-1-tungsta)-2,10-diphenyl-12H-
1,3,13-trioxa-dibenzo[a,kl]anthracen-7-yl]-3-phenyl-acrylic acid ethyl
ester (10b)
Rf = 0.65 (petroleum ether (30–60 °C)/dichloromethane (v/v,
1/2)). Green crystals (198 mg, 75%) were obtained by recrystalliza-
tion from n-pentane/dichloromethane (v/v, 10/1) at ꢁ20 °C. M.p.:
176 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d 8.33 (s, 1H), 7.62
(d, 1H, J = 9.60 Hz), 7.56 and 7.52–7.41 (m each, 5:5H), 7.27–7.17
and 7.11 (m each, 6:3H), 6.93 (s, 1H), 5.31 and 4.22 (d each,
1:1H, J = 12.8 Hz, CH2), 4.81 and 4.56 (q each, 1:1H, OCH2), 3.11
(q, 2H, OCH2), 1.19 and ꢁ0.20 (t each, 3:3H, 2 ꢂ CH3); 13C{1H}NMR
(CDCl3, 23 °C, 100 MHz) d 327.36 and 256.79 (Cq each, 1:1, W@C,
C20 and C12), 204.48 and 198.99 (Cq each, 1:4, trans- and cis-CO,
C20–W(CO)5), 204.06 and 197.44 (Cq each, 1:4, trans- and cis-CO,
C12–W(CO)5), 165.50, 164.44, 150.58, 148.55, 148.17, 143.27,
142.01, 139.05, 138.82, 135.09, 132.17, 130.24, 130.18, 129.30,
129.21, 129.09, 128.87, 128.38, 127.75, 127.45, 127.24, 125.86,
122.40, 122.24, 119.34, 119.04, 112.78, 109.71, 108.57, 104.24,
80.66 (CH2), 73.52 and 59.87 (2 ꢂ OCH2), 14.24 and 13.16
(2 ꢂ CH3). Anal. Calc. for C55H34O16 W2: C, 50.10; H, 2.60. Found:
C, 50.23; H, 2.65%.
1''
EtO
1''
EtO
2'
3
3'
2'
3'
Cr(CO)5
Cr(CO)5
Ph
O
Ph
O
12
11
12
11
O13
1' O
(CO)5Cr
2
1
2
O
O13
3
1
O
1'
4
5
10
4
10
Ph
Ph
6
6
5
9
9
7
7
8
8
OEt
OEt
3'''
3'''
1'''
1'''
O
Ph
O
Ph
2'''
2'''
4.3.8. 3-[2-(2-Ethoxy-1,1,1,1,1-pentacarbonyl-1-chroma-1-propen-3-
yl)-12-(1,1,1,1,1-pentacarbonyl-1-chroma)-2,10-diphenyl-12H-
1,3,13-trioxa-dibenzo[a,kl]anthracen-7-yl]-3-phenyl-acrylic acid ethyl
ester (10a)
4.3.10. 3-[2-(2-Ethoxycarbonylmethyl)-12-(1,1,1,1,1-pentacarbonyl-
1-chroma)-2,10-diphenyl-12H-1,3,13-trioxa-dibenzo[a,kl]anthracen-
7-yl]-3-phenyl-acrylic acid ethyl ester (11a)
Rf = 0.50 (100% dichloromethane). Green crystals (167 mg, 95%)
were obtained by recrystallization from n-pentane/dichlorometh-
ane (v/v, 10/1) at ꢁ20 °C. M.p.: 158 °C, dec. 1H NMR (CDCl3,
23 °C, 400 MHz) d 8.31 (s, 1H), 7.68 (m, 2H), 7.62–7.57 (m, 6H),
7.49-7.40 (m, 3H), 7.30–7.22 (m, 6H), 7.12 (m, 3H), 6.94 (s, 1H),
4.13 (m, 2H, OCH2), 4.02 and 3.85 (d each, 1:1H, J = 14.4 Hz, CH2),
3.12 (q, 2H, OCH2), 1.18 and ꢁ0.16 (t each, 3:3H, 2 ꢂ CH3);
13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d 282.90 (Cq, Cr@C), 224.61
and 217.97 (Cq each, 1:4, trans- and cis-CO, Cr(CO)5),
167.73, 167.66, 165.71, 165.55, 151.75, 150.69, 148.75,
148.42, 139.94, 139.25, 139.16, 138.89, 138.76, 138.29, 135.15,
135.04, 132.18, 130.15, 129.59, 129.42, 129.18, 129.08, 129.02,
128.87, 128.28, 128.13, 127.82, 127.34, 127.26, 127.21, 125.63,
125.36, 122.48, 122.25, 121.57, 119.24, 118.97, 118.57, 112.93,
110.00, 109.92, 108.53, 103.68, 60.94 (CH2), 59.92 and 47.92
(2 ꢂ OCH2), 14.14 and 13.21 (2 ꢂ CH3). Anal. Calc. for C50H34O12Cr:
C, 68.34; H, 3.90. Found: C, 68.46; H, 3.96%.
Rf = 0.65 (petroleum ether (30–60 °C)/dichloromethane (v/v,
1/2)). Green crystals (183 mg, 87%) were obtained by recrystalliza-
tion from n-pentane/dichloromethane (v/v, 10/1) at ꢁ20 °C. M.p.:
150 °C, dec. 1H NMR (CDCl3, 23 °C, 400 MHz) d 8.30 (s, 1H),
7.58 (m, 8H), 7.45 (m, 3H), 7.27 (m, 5H), 7.12 (m, 4H), 6.93 (s,
1H), 5.41 and 4.51 (d each, 1:1H, J = 14.0 Hz, CH2), 5.10 and 4.98
(q each, 1:1H, OCH2), 3.11 (q, 2H, OCH2), 1.37 and ꢁ0.14 (t each,
3:3H, 2 ꢂ CH3); 13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d 354.33
and 283.22 (Cq each, 1:1, Cr@C, C20 and C12), 224.16 and 216.18
(Cq each, 1:4, trans- and cis-CO, C20–Cr(CO)5), 223.76 and 218.13
(Cq each, 1:4, trans- and cis-CO, C12–Cr(CO)5), 165.66, 165.55,
150.69, 148.56, 148.18, 139.80, 139.30, 139.24, 138.86, 135.03,
132.09, 130.21, 130.16, 130.09, 129.59, 129.19, 129.10, 128.80,
128.34, 127.77, 127.25, 125.55, 122.55, 122.24, 119.28, 118.55,
112.73, 109.45, 108.47, 104.25, 78.22 and 71.14 (2 ꢂ OCH2),
59.88 (CH2), 14.73 and 13.26 (2 ꢂ CH3). Anal. Calc. for
C55H34O16Cr2: C, 62.62; H, 3.25. Found: C, 62.55; H, 3.30%.
1''
1''
EtO
EtO
2'
2'
3'
W(CO)5
3'
W(CO)5
Ph
Ph
12
12
1'O
(CO)5W
2
2
3
1
3
1
11
11
O
O
O13
O
O
O13
1'
4
5
10
4
10
Ph
Ph
6
6
5
9
9
7
7
8
8
OEt
OEt
3'''
3'''
1'''
1'''
O
Ph
O
Ph
2'''
2'''

N. Luo, Z.K. Yu / Journal of Organometallic Chemistry 694 (2009) 3058–3067
3067
4.3.11. 3-[2-(2-Ethoxycarbonylmethyl)-12-(1,1,1,1,1-pentacarbonyl-
1-tungsta)-2,10-diphenyl-12H-1,3,13-trioxa-dibenzo[a,kl]anthracen-
7-yl]-3-phenyl-acrylic acid ethyl ester (11b)
and polarization effects and empirical absorption. The structures
were solved by direct methods and refined by full-matrix least
squares on F2. All non-hydrogen atoms were refined anisotropi-
cally. All hydrogen atoms were placed in calculated positions.
Structure solution and refinement were performed by using the
SHELXL-97 package. Crystal data and refinement details for these
compounds are summarized in Table 2, and the selected bond dis-
tances and angles are listed in Table 3.
Rf = 0.50 (100% dichloromethane). Brown crystals (188 mg, 93%)
were obtained by recrystallization from dichloromethane/n-pen-
tane (v/v, 1/10) at ꢁ20 °C. M.p.: 145–147 °C. 1H NMR (CDCl3,
23 °C, 400 MHz) d 8.34 (s, 1H), 7.67–7.62 and 7.57 (m each,
3:6H), 7.52–7.38 (m, 4H), 7.32–7.17 (m, 4H), 7.15–7.09 (m, 3H),
6.94 (s, 1H), 4.10 (m, 2H, OCH2), 3.99 and 3.82 (d each, 1:1H,
J = 14.0 Hz, CH2), 3.12 (m, 2H, OCH2), 1.15 and ꢁ0.20 (t each,
3:3H, 2 ꢂ CH3); 13C{1H}NMR (CDCl3, 23 °C, 100 MHz) d 256.68
(Cq, W@C), 204.72 and 198.89 (Cq each, 1:4, trans- and cis-CO,
W(CO)5), 167.60, 165.52, 164.47, 150.58, 148.75, 148.40, 143.34,
141.97, 138.85, 138.17, 135.11, 132.24, 130.28, 130.15, 129.32,
129.21, 129.08, 128.33, 128.20, 127.74, 127.49, 127.25, 125.88,
122.35, 122.26, 119.27, 119.02, 112.91, 109.99, 108.59, 103.62,
60.93, 59.91, 48.22, 14.09, 13.12. Anal. Calc. for C50H34O12W: C,
59.42; H, 3.39. Found: C, 59.35; H, 3.32%.
Acknowledgements
We are grateful to the National Natural Science Foundation of
China (20772124) and the National Basic Research Program of Chi-
na (2009CB825300) for support of this research.
Appendix A. Supplementary material
CCDC 701684, 701685, 701686 and 701687 contain the supple-
mentary crystallographic data for 3, 4b, 5a and 12. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplemen-
tary data associated with this article can be found, in the online
version, at doi:10.1016/j.jorganchem.2009.05.029.
EtO
2''
3
3''
O
Ph
O
12
1'' O
2
1
11
O
O13
10
4
5
Ph
6
9
7
8
OEt
References
3'
1'
O
Ph
2'
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4.3.12. 3-[2-(2-Ethoxycarbonylmethyl)-12-oxo-2,10-diphenyl-12H-
1,3,13-trioxa-dibenzo[a,kl]anthracen-7-yl)]-3-phenyl-acrylic acid
ethyl ester (12)
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[19] Z.Y. Zheng, J.Z. Chen, N. Luo, Z.K. Yu, X.W. Han, Organometallics 25 (2006)
5301.
Rf = 0.50 (dichloromethane/diethyl ether, v/v, 1/1). Yellow crys-
tals (133 mg from M = Cr, 95%; 128 mg from M = W, 91%). Single
crystals were obtained by recrystallization from n-pentane/dichlo-
romethane (v/v, 4/1) at room temperature. M.p.: 250 °C, dec. 1H
NMR (CDCl3, 23 °C, 400 MHz)
d 7.90 (s, 1H), 7.88 (s, 1H),
7.50–7.44 (m, 6H), 7.38 (m, 2H), 7.25–7.12 (m, 10H), 6.91 (s, 1H),
6.50 (s, 1H), 4.12 (m, 2H, OCH2), 3.62 and 3.51 (d each, 1:1H,
J = 14.5 Hz, CH2), 3.33 and 3.19 (m each, 1:1H, OCH2), 1.16 and
ꢁ0.16 (t each, 3:3H, 2 ꢂ CH3); 13C{1H}NMR (CDCl3, 23 °C,
100 MHz)
d 167.76, 165.65, 160.78, 156.42, 153.49, 151.02,
148.33, 146.58, 139.27, 139.19, 135.97, 131.31, 131.07, 129.97,
129.62, 129.17, 128.99, 128.95, 128.66, 128.53, 127.32, 127.27,
126.32, 122.96, 122.20, 122.03, 119.05, 113.93, 113.48, 111.86,
109.23, 108.78, 102.24, 60.94, 59.89, 47.53, 14.16, 12.86. HRMS
calcd for C45H34O8: 702.2254. Found: 702.2247.
[20] Z.Y. Zheng, J.Z. Chen, N. Luo, Z.K. Yu, X.W. Han, J. Organomet. Chem. 691 (2006)
3679.
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4.4. X-ray crystallographic studies
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(2007) 4001.
Single crystal for X-ray diffraction studies for compounds 3, 4b,
5a, and 12 were carried out on a SMART APEX diffractometer with
graphite-monochromated Mo K
a radiation (k = 0.71073 Å). Cell
parameters were obtained by global refinement of the positions
of all collected reflections. Intensities were corrected for Lorentz
[26] C. Leimkuhler, M. Fridman, T. Lupoli, S. Walker, C.T. Walsh, D. Kahne, J. Am.
Chem. Soc. 129 (2007) 10546.