Iron-catalyzed ferrocenylmethanol OH substitution by S, N, P, and C nucleophiles

Article abstract of DOI:10.1002/ejic.201300239

The iron complex [Fp][OTf] {Fp⁺ = [Fe(CO)₂(Cp)] ⁺, OTf^- = SO₃CF₃^-} is an efficient catalyst for the direct substitution of the OH group in ferrocenylmethanol [Fc-CH₂OH] by thiols, aromatic amines, diphenylphosphane, and carbon nucleophiles (furan, pyrrole, and indole). This approach offers a convenient route to ferrocenes containing side chains with different functional groups. The advantages of the method are associated with the use of a catalyst based on iron, which is a nontoxic and readily available transition metal, and in the direct OH substitution, which produces water as the only byproduct. Direct substitution of the OH group in ferrocenylmethanol by S, N, P, and C nucleophiles containing an active hydrogen atom (thiols, aromatic amines, diphenylphosphane, furan, pyrrole, indole) can be accomplished by use of the iron catalyst [Fe(CO)₂(Cp)][OTf] (Cp = cyclopentadienyl, OTf = SO₃CF₃). Copyright

Full text of DOI:10.1002/ejic.201300239

FULL PAPER
DOI:10.1002/ejic.201300239
Iron-Catalyzed Ferrocenylmethanol OH Substitution by S,
N, P, and C Nucleophiles
Rita Mazzoni,[a] Mauro Salmi,[a] Stefano Zacchini,[a] and
Valerio Zanotti*[a]
Keywords: Iron / Ferrocene / Nucleophilic substitution / Phosphanes / C–C bond formation / Sustainable chemistry
The iron complex [Fp][OTf] {Fp+ = [Fe(CO)2(Cp)]+, OTf–
=
different functional groups. The advantages of the method
are associated with the use of a catalyst based on iron, which
is a nontoxic and readily available transition metal, and in
the direct OH substitution, which produces water as the only
byproduct.
SO3CF3–} is an efficient catalyst for the direct substitution of
the OH group in ferrocenylmethanol [Fc–CH2OH] by thiols,
aromatic amines, diphenylphosphane, and carbon nucleo-
philes (furan, pyrrole, and indole). This approach offers a
convenient route to ferrocenes containing side chains with
Lewis acids catalysts (e.g., indium tribromide,[7] ytterbium
triflate,[8] or bismuth nitrate).[9] A procedure based on ce-
rium ammonium nitrate (CAN), which presumably takes
advantage of one-electron oxidation properties of the cata-
lyst, has been described.[10] Secondary and tertiary ferro-
cenyl alcohols, which generate more stable carbenium cat-
ions, can undergo OH substitution even “on water” and
without added Lewis acids.[11] The activation of ferrocenyl-
methanol provides a convenient and straightforward ap-
proach to functionalized ferrocenes, which are extremely
valuable organometallic scaffolds for the construction of
molecules with applications in catalysis, materials science,
and biomedicinal chemistry.[12] We have recently shown that
dehydrative etherification of ferrocenylmethanol 1 with a
variety of alcohols is efficiently catalyzed by the iron
Introduction
The increasing demand for green and sustainable chemi-
cal transformations has produced an impressive effort to
design more efficient and environmentally benign bond-
forming reactions.[1] In this respect, a highly challenging
task is the direct use of alcohols instead of alkyl halides in
reactions with nucleophiles, which is one of the most useful
protocols for carbon–carbon and carbon–heteroatom bond
formation. The use of alcohols is advantageous from the
viewpoint of atom efficiency and because water is the only
byproduct. However, this approach is limited by the poor
leaving-group ability of the OH group. A number of syn-
thetic protocols have been recently developed to promote
OH substitution, based on organometallic catalysts, but
most significant results are essentially limited to π-activated
alcohols, such as allyl, benzyl, and propargyl alcohols. Ex-
amples include Pd-catalyzed nucleophilic allylic[2] and benz-
ylic[3] substitution, ruthenium-catalyzed propargylic OH
substitution,[4] and gold-catalyzed dehydrative transforma-
tion of unsaturated alcohols.[5]
complex [Fp][OTf] {Fp+
= =
[Fe(CO)2(Cp)]+, OTf–
–
SO3CF3 }[13] (Scheme 1).
Activated alcohols also include ferrocenylmethanol [Fc–
CH2OH] (1, Fc = ferrocenyl) and related α-substituted spe-
cies, such as 1-ferrocenylethanol [Fc–CH(Me)OH], ferro-
cenyl(phenyl)methanol [Fc–CH(Ph)OH], and diferrocenyl-
methanol [Fc2–CHOH], in which OH displacement is fa-
vored by formation of a relatively stabilized carbenium cat-
ion.[6] Direct nucleophilic substitution of the OH group in
ferrocenyl alcohols is generally accomplished by using
Scheme 1.
An advantage of our method over other previously re-
ported approaches is the use of a catalyst based on iron,
which is a nontoxic, environmentally benign and cost-effec-
tive transition metal.[14] In light of the above considerations,
we decided to extend our investigations on [Fp][OTf]-cata-
lyzed OH substitution in ferrocenylmethanol to a broader
[a] Dipartimento di Chimica Industriale “Toso Montanari”,
Università di Bologna,
Viale Risorgimento 4, 40136 Bologna, Italy
Fax: +39-0512093690
E-mail: valerio.zanotti@unibo.it
Homepage: http://www.unibo.it/docenti/valerio.zanotti
Eur. J. Inorg. Chem. 2013, 3710–3718
3710
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
variety of nucleophies (thiols, amines, carbon nucleophiles, CH2Cl2 solution at room temperature. The reaction
etc.) to generate C–C and C–heteroatom bonds. The aim (Table 1) leads to the formation of the corresponding ferro-
was to demonstrate that iron-catalyzed OH substitution can cenyl thioethers 3a–i in high yields.
Compounds 3a–i have been characterized by NMR spec-
troscopy and elemental analysis. Their spectroscopic data
have been compared with those reported in the literature, if
available. Indeed, complexes 3a, 3g,[15] 3b,[16] 3c,[17] 3e,[10b]
3h,[18] and 3i[19] have been previously obtained by different
methods. Moreover, the molecular structure of 3b has been
determined by X-ray diffraction. The ORTEP diagram is
shown in Figure 1, and the main bond lengths and angles
are reported in Table 2.
provide a new and convenient approach to ferrocene func-
tionalization.
Results and Discussion
Reactions of Ferrocenylmethanol with Thiols
Based on the results shown in Scheme 1 and in consider-
ation of the analogies between alcohols and thiols, we first
investigated the OH substitution by thiols. The conditions
The unit cell of 3b contains two independent molecules
under which these reactions have been performed require with almost identical geometries and bonding parameters.
the use of a slight excess of thiol with respect to 1 (1:1.5 Complex 3b is a monosubstituted ferrocene with the two
ratio) in the presence of [Fp][OTf] (10mol-% to 1) in Cp-rings almost parallel [the angles between the least-
Table 1. Reactions of ferrocenylmethanol with thiols catalyzed by [Fp][OTf].
[a] Reaction conditions: 1/thiol ratio = 1:1.5, in CH2Cl2 at room temperature. [b] Isolated yields after 1 h reaction.
Eur. J. Inorg. Chem. 2013, 3710–3718
3711
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
[FpPhSH]+ has been described,[23] but the reaction is quite
slow and should not interfere significantly.
A further observation is that the iron-catalyzed de-
hydrative thioetherification of 1 is selective and leads to the
formation of one single product. This is particularly evident
in the reactions of 1 with species that contain both thiol
and hydroxy groups (Table 2, Entries 6 and 7), which, in
theory, might produce both thioethers and ethers. Con-
versely, thioetherification takes place selectively, which is
consistent with the stronger nucleophilic properties of thiols
compared to alcohols. In addition to these examples, com-
petition between OH and SH is always present in all the
reactions examined, as ferrocenylmethanol itself can act as
nucleophile, and the self-condensation product [Fc–
CH2OCH2–Fc] (4) might be expected if the added nucleo-
phile (thiol) were to react too slowly. Indeed, it is known
that 1, upon treatment with [Fp][OTf], in the absence of
other nucleophiles, generates the symmetric ether 4, but the
reaction is rather sluggish (Scheme 2).[12]
Figure 1. ORTEP diagram of 3b. Thermal ellipsoids are drawn at
30% probability level. Only one of the two independent molecules
present in the unit cell is represented.
Table 2. Selected bond lengths [Å] and angles [°] for 3b.
Molecule 1
Molecule 2
Fe(1)–Cp(1)[a]
2.028(3)–2.040(3)
Average 2.034(6)
2.018(3)–2.045(3)
Average 2.027(6)
1.399(4)–1.422(3)
Average 1.409(9)
1.366(4)–1.450(5)
Average 1.390(9)
1.488(4)
2.030(2)–2.045(3)
Average 2.036(6)
2.021(3)–2.039(3)
Average 2.031(6)
1.391(4)–1.422(4)
Average 1.409(9)
1.382(4)–1.417(6)
Average 1.400(9)
1.488(3)
[b]
Fe(1)–Cp(2)
[a]
C–C Cp(1)
C–C Cp(2)[b]
C(1)–C(6)
C(6)–S(1)
S(1)–C(7)
Scheme 2.
1.827(3)
1.762(3)
1.822(2)
1.765(2)
Finally, the reaction of 1 with 2-aminobenzenethiol
(Table 1, Entry 9) provides a comparison between the
amino and thiol groups: again, the reaction is selective and
OH displacement is performed exclusively by the thiol func-
tion. Therefore, reactions of 1 with thiols containing other
functional groups provide both an indication of which nu-
cleophile more effectively replaces the OH group and easy
access to ferrocenyl complexes with a functionalized side
chain. This pending function is potentially able to coordi-
nate to other metal centers or connect to different molecu-
lar fragments, which is an important feature for possible
application.
Sum angles Cp(1)[a]
Sum angles Cp(2)[b]
C(1)–C(6)–S(1)
540.0(5)
540.1(5)
107.56(18)
103.69(12)
540.0(5)
540.1(5)
107.20(18)
103.89(12)
C(6)–S(1)–C(7)
[a] Cp(1) is defined by atoms C(1), C(2), C(3), C(4), and C(5). [b]
Cp(2) is defined by atoms C(13), C(14), C(15), C(16), and C(17).
squares mean planes of the five-membered rings are 1.3 and
1.0° for the two independent molecules. The Fe–C interac-
tions with the substituted C5 ring [average 2.034(6) and
2.036(6) Å] are substantially longer than those with the un-
substituted Cp ring [average 2.027(6) and 2.031(6) Å].[13]
The reactions shown in Table 1 are interesting examples
of the relatively uncommon catalytic OH substitution by
thiols; thioethers are usually obtained upon reaction of hal-
ides with thiolates. Indeed, dehydrative thioetherification,
Reactions of Ferrocenylmethanol with Amines, Phosphanes,
and Carbon Nucleophiles
After examination of the OH substitution by alcohols
catalyzed by transition-metal complexes, is essentially lim- and thiols, we turned our attention to group 15 nucleo-
ited to allylation of thiols based on ruthenium catalysts.[20] philes. The reaction of alcohols with amines is a clear-cut
Direct reactions between ferrocenyl alcohols and thiols but very challenging method for the synthesis of N-alkyl-
mostly concern α-substituted ferrocenyl alcohols such as ated amines. One of the most promising approaches to am-
[Fc–CH(R)OH] (R = Me, Ph, Fc).[10,11,21] However, it has ination of alcohols is based on the oxidation–imination–
been reported that 3a and 3g can be obtained by reaction reduction sequence: the alcohol, once oxidized and attacked
of 1 with thiols in the presence of acetic acid, but the reac- by an amine, affords a hemiaminal. This intermediate can
tion is performed with a large excess of thiol (50% mixture dehydrate to an imine and be hydrogenated to generate an
of water and thiol used as solvent).[15] Interestingly, the cat- amine. Methods in which this sequence is performed as a
alyst [Fp][OTf] is not inactivated (or “poisoned”) by thiols, one-pot reaction and the oxidation step consists of a de-
although these are potentially able to coordinate to the iron hydrogenation are described as “borrowing hydrogen” or
complex.[22] For example, the addition of HSPh to “hydrogen autotransfer” reactions. This area has recently
[Fp(THF)][BF4] (THF
=
tetrahydrofuran) to form witnessed an impressive development, mostly based on
Eur. J. Inorg. Chem. 2013, 3710–3718
3712
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
homogeneous ruthenium and iridium catalysts.[24] On the Table 3. Reactions of ferrocenylmethanol with amines catalyzed by
[Fp][OTf].
other hand, the direct combination of alcohols and amines
does not necessarily imply a redox mechanism; acid-cata-
lyzed nucleophilic OH substitution by amines in π-activated
alcohols is also feasible. A few examples of the amination
of ferrocenyl alcohols by anilines (arylamines) are known
and, although detailed mechanistic investigations have not
been presented, it has been suggested that these reactions
occur via ferrocenyl carbenium intermediates.[10b,21]
Based on these considerations, we investigated the reac-
tions of 1 with different amines in the presence of [Fp][OTf]
as catalyst. The results are shown in Table 3.
In agreement with previous findings,[10b,21] amination re-
actions are limited to arylamines (Table 3, Entries 1 and 2).
The reactions with other amines (Table 3, Entries 3–5) lead
to the formation of the symmetric ether 4 as the only ob-
served product. Therefore, amines do not deactivate the cat-
alyst, and self-condensation of 1 takes place, although the
reaction is relatively slow and almost complete conversion
occurs in ca. 16 h, which is in agreement with the conditions
usually observed for the conversion of 1 into 4 in the ab-
sence of nucleophiles. The absence of catalyst deactivation
is remarkable as amine complexes of Fp+ are known and
can be prepared from [Fp(Et2O)][BF4] and alkylamines.[25]
On the other hand, it has been reported that Fp+ also acts
as a catalyst in the presence of 1,8-bis(dimethylamino)-
naphthalene, which is potentially able to deactivate it.[26]
Complexes 5a and 5b have been characterized by NMR
spectroscopy and elemental analysis; moreover, the molecu-
lar structure of 5a has been determined by the X-ray dif-
fraction (Figure 2 and Table 4).
The unit cell of 5a contains two independent molecules
with almost identical geometries and bonding parameters.
Compound 5a closely resembles 3b; the replacement of the
thioether group with the amino group is the major differ-
ence. Hydrogen bonding is present between the N–H group
of one molecule and the nitro substituent of the other one
[donor–acceptor distance 3.066(2) Å, angle 163(2)°].
Our results are consistent with those previously reported
by Ji and co-workers concerning the reactions of ferrocenyl
alcohols with arylamines catalyzed by cerium ammonium
nitrate, including the reaction of 1 with p-chloroaniline.[10b]
In that report, the authors evidenced a higher reactivity for
arylamines with electron-withdrawing groups (in the para
position). Conversely, in our case, we did not observed any
relevant effect, and 4-nitroaniline and 4-isopropylaniline
(Table 3, Entries 1 and 2, respectively) gave similar results.
[a] Reaction conditions: 1/nucleophile ratio = 1:1.5, in CH2Cl2 at
An interesting and unprecedented outcome was found in
room temperature. [b] Isolated yields after 2 h of reaction. [c] Iso-
the reaction of 1 with diphenylphosphane (Table 3, Entry
6). Complex 1 undergoes OH displacement by diphenyl-
phosphane to afford the ferrocenylphosphane complex 6,
lated yields after 16 h of reaction.
but the reaction is not selective and a comparable amount complexes are not prepared from ferrocenyl alcohols by di-
of the self-condensation product 4 is also formed. Ferro- rect OH nucleophilic substitution; the hydroxy group must
cenes containing a phosphane group at the α-position of be converted into a better leaving group, which usually re-
the side chain are known. Examples include [FcCH2PH2][27] quires
a sequence of transformations. For example,
and [FcCH2PR(CH2CH2OH)][28] (R = Me, CH2CH2OH), [FcCH(Me)P(CH2CH2OH)2] is obtained by conversion of
which exhibit interesting chemistry associated with the co- ferrocenyl alcohol into acetate, which is reacted further with
ordinating properties of the phosphorus atom.[27] These diethylamine, followed by methyl iodide to generate
Eur. J. Inorg. Chem. 2013, 3710–3718
3713
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
with the catalyst. Indeed, the complex [FpPPh2H]+ is
known,[33] and one of the possible synthetic routes is the
reaction of [Fp(THF)][PF6] with PPh2H.[34] Moreover, we
have verified that, under our reaction conditions, but with-
out ferrocenylmethanol, the catalyst rapidly reacts with
PPh2H to form [FpPPh2H][OTf]. Therefore, it is surprising
that the catalytic activity of [Fp][OTf] is preserved and re-
sults in the formation of both C–P and C–O bonds (prod-
ucts 6 and 4, respectively).
Table 5. Reactions of ferrocenylmethanol with carbon nucleophiles
catalyzed by [Fp][OTf].
Figure 2. ORTEP diagram of 5a. Thermal ellipsoids are drawn at
30% probability level. Only one of the two independent molecules
present in the unit cell is represented.
Table 4. Selected bond lengths [Å] and angles [°] for 5a.
Molecule 1
Molecule 2
Fe(1)–Cp(1)[a]
Fe(1)–Cp(2)[b]
C–C Cp(1)[a]
C–C Cp(2)[b]
2.0248(19)–2.041(2) 2.028(2)–2.047(2)
average 2.036(4)
2.026(2)–2.042(2)
average 2.033(4)
1.400(4)–1.421(3)
average 1.412(7)
1.388(4)–1.402(4)
average 1.396(9)
1.497(3)
average 2.038(4)
2.005(9)–2.036(8)
average 2.02(2)
1.391(4)–1.422(3)
average 1.409(7)
1.399(10)–1.434(10)
average 1.41(2)
1.489(3)
C(1)–C(6)
C(6)–N(1)
N(1)–C(7)
1.457(3)
1.457(3)
1.352(3)
1.351(3)
Sum angles Cp(1)[a]
Sum angles Cp(2)[b]
C(1)–C(6)–N(1)
539.9(4)
540.0(4)
111.03(18)
123.32(18)
540.0(4)
540.0(16)
110.68(18)
123.64(18)
C(6)–N(1)–C(7)
[a] Cp(1) is defined by atoms C(1), C(2), C(3), C(4), and C(5). [b]
Cp(2) is defined by atoms C(13), C(14), C(15), C(16), and C(17).
[FcCH(Me)NEt2Me][I]. This latter undergoes nucleophilic
substitution by the phosphane.[29] The introduction of a
side chain containing a phosphane group is also a funda-
mental step in the modular approach to ferrocenyl diphos-
phane ligands (Josiphos-type),[30] which are among the
most versatile chelating phosphorus ligands for catalytic ap-
plications.[31] In particular, the introduction of a phos-
phorus moiety in the pseudo-benzylic position (α position)
is accomplished by nucleophilic substitution of suitable
leaving groups. In general, these are dimethylamino (from
Ugi’s amine) or methoxy groups, and the nucleophilic sub-
stitution takes place with retention of configuration.[32]
Moreover, transformation of OH into OMe also allows the
ortho-lithiation of the Cp ring, which is necessary for the
introduction of a second phosphorus function directly on
the cylopentadienyl ring. In light of these considerations,
the formation of 6, although low yielding, appears unique,
in that it results from the direct reaction of ferrocenylme-
thanol with a secondary phosphane. Again, it has to be
outlined that the catalytic activity of [Fp][OTf] is retained
[a] Reaction conditions: 1/nucleophile ratio = 1:1.5, in CH2Cl2 at
despite the presence of a reagent (PPh2H) that can react room temperature. [b] Isolated yields after 4 h of reaction.
Eur. J. Inorg. Chem. 2013, 3710–3718
3714
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
distilled immediately before use under nitrogen from appropriate
drying agents. Chromatography separations were performed on col-
umns of deactivated alumina (4% w/w water). Glassware was oven-
dried before use. Infrared spectra were recorded at 298 K with a
Perkin–Elmer Spectrum 2000 FTIR spectrophotometer, and ele-
mental analyses were performed with a ThermoQuest Flash 1112
Series EA Instrument. All NMR measurements were performed
with a Varian Mercury Plus 400 instrument and were recorded at
Finally, we have investigated the nucleophilic substitution
of the hydroxy group in 1 with carbon nucleophiles
(Table 5). Our results evidence that the iron complex
[Fp][OTf] is also a good catalyst for OH substitution in 1
by different carbon nucleophiles to result in the formation
of a C–C bond at the α position of the side chain.
The reactions reported in Table 5 involve active C–H
bonds in heterocyclic aromatic compounds such as pyrrole,
furan, and indole. Unexpectedly, thiophene and other active
1
298 K. H and 13C chemical shifts were referenced to internal tet-
ramethylsilane (TMS). NMR spectra were assigned through DEPT
methylene species (acetylacetone and dimethylmalonate) experiments and 1H–13C correlation measured through gradient-
selected heteronuclear single quantum coherence (gs-HSQC) and
gs-HMBC experiments. All reagents were commercial products
(Aldrich) of the highest purity available and were used as received.
[Fe2(CO)4(Cp)2] was purchased from Strem and used as received.
Owing to its high reactivity, the iron complex [Fp][OTf] was freshly
prepared immediately before use, by reacting [Fe2(Cp)2(CO)4] with
AgOTf, according to the procedure previously reported.[13]
were unreactive. This is in contrast with previous findings in
similar reactions performed in acetic acid,[21] or with cerium
[7]
ammonium nitrate[10a] or InBr3 as catalyst, and even in
water,[11] in which diketones and keto esters were reactive.
On the other hand, these previously reported examples al-
most exclusively involve secondary ferrocenyl alcohols [e.g.,
Fc–CH(Me)OH], which are more reactive than 1. Thus, our
synthetic approach is somewhat complementary. For exam-
ple, 1 was previously found to be unreactive toward pyr-
role,[10a] whereas, in our case (Table 5, Entry 2), the reaction
takes place in moderate yield. Concerning the reaction with
furfuryl alcohol (Table 5, Entry 3), which in theory displays
two competitive nucleophilic sites (the hydroxy and the
active methylene carbon), we exclusively observed C–O
bond formation to yield the etherification product 9
(Table 5, Entry 3). Finally, the reaction with indole cata-
lyzed by [Fp][OTf] gives results similar to those reported
for the ferrocenyl alkylation of indoles promoted by a BiIII
catalyst, which also afforded 10 in comparable yield.[9]
[Fc–CH2SR] [R = Et, 3a; R = Ph, 3b; R = CH2Ph, 3c; R =
CH2CH=CH2, 3d; R = C9H7, 3e; R = (CH2)3SH, 3f; R =
CH2CH2OH, 3 g; R = CH2CH(OH)CH2OH, 3h; R = o-NH2C6H4,
3i]: The catalyst [Fp][OTf] (0.05 mmol) in CH2Cl2 solution (10 mL)
was added to a solution of ferrocenylmethanol (1, 108 mg,
0.50 mmol) and ethanethiol (0.05 mL, 0.75 mmol) in CH2Cl2
(20 mL). The resulting mixture was stirred at room temperature for
1 h. After removal of the solvent and chromatography of the resi-
due on alumina with petroleum ether (b.p. 40–60 °C) as eluent, 3a
was obtained as a yellow solid, yield 121 mg, 93%. C13H16FeS
1
(260.18): calcd. C 60.01, H 6.20; found C 60.09, H 6.32. H NMR
(CDCl3): δ = 4.18 (m, 2 H, Cp), 4.14 (s, 5 H, Cpfree), 4.11 (m, 2 H,
3
Cp), 3.53 (s, 2 H, CpCH2), 2.49 (q, JH,H = 7.4 Hz, 2 H,
3
SCH2CH3), 1.23 (t, JH,H = 7.4 Hz, 3 H, SCH2CH3) ppm. 13C
NMR (CDCl3): δ = 85.4 (Cipso-Cp), 68.6 (Cpfree), 68.5, 67.8 (Cp),
31.4 (CpCH2), 25.8, 14.5 (SCH2CH3) ppm.
Conclusions
Compounds 3b–i were prepared by the same procedure as that de-
scribed for 3a, by reacting 1 with the appropriate thiol. Crystals of
3b suitable for X-ray analysis were obtained by slow evaporation
from a CH2Cl2 solution.
The iron complex [Fp][OTf] is an excellent catalyst in the
direct ferrocenylmethanol OH substitution. Different nu-
cleophiles have been examined including thiols, arylamines,
diphenylphosphane, and carbon nucleophiles, which lead to
the formation of C–S, C–N, C–P, and C–C bonds. There-
fore, this approach offers functionalized ferrocenes contain-
ing a side chain with functional groups. Interestingly,
[Fp][OTf] acts as a Lewis acid catalyst despite the presence
of nucleophiles (thiols, amines, and phosphane) that can
3b: Yield 135 mg, 88%. C17H16FeS (308.22): calcd. C 66.25, H 5.23;
found C 66.37, H 5.14. 1H NMR (CDCl3): δ = 7.49–7.13 (5 H, Ph),
4.13–4.11 (7 H, Cpfree and Cp), 4.06 (m, 2 H, Cp), 3.89 (s, 2 H,
CpCH2) ppm. 13C NMR (CDCl3): δ = 136.0 (Cipso-Ph), 129.8–126.1
(Carom), 84.3 (Cipso-Cp), 68.7 (Cpfree), 68.6, 67.9 (Cp), 34.8 (CpCH2)
ppm.
potentially react and give stable addition products. Com- 3c: Yield 145 mg, 90%. C18H18FeS (322.25): calcd. C 67.09, H 5.63;
found C 66.97, H 5.13. 1H NMR (CDCl3): δ = 7.30–7.12 (5 H, Ph),
pared to previously reported methods for the direct OH
substitution of ferrocenyl alcohols, our approach exhibits
two distinct features: one is the use of an iron catalyst and
mild reaction conditions without the need for a large excess
4.07 (m, 2 H, Cp), 4.03 (7 H, Cpfree and Cp), 3.58 (s, 2 H, CH2Ph),
3.34 (s, 2 H, CpCH2) ppm. 13C NMR (CDCl3): δ = 138.4
(Cipso-Ph), 129.4–126.9 (Carom), 84.9 (Cipso-Cp), 68.7 (Cpfree and Cp),
67.9 (Cp), 36.2 (CH2Ph), 31.2 (CpCH2) ppm.
of the nucleophile. The second aspect is that direct OH sub-
3d: Yield 114 mg, 84%. C14H16FeS (272.19): calcd. C 61.78, H 5.92;
found C 61.87, H 5.93. 1H NMR (CDCl3): δ = 5.73 (m, 1 H,
CH=CH2), 5.24 (m, 2 H, CH=CH2), 4.17 (m, 2 H, Cp), 4.12 (s, 5
H, Cpfree), 4.11 (m, 2 H, Cp), 3.45 (s, 2 H, CpCH2), 3.06 (m, 2 H,
SCH2) ppm. 13C NMR (CDCl3): δ = 133.4, 115.9 (CH=CH2), 84.1
(Cipso-Cp), 67.8 (Cpfree), 67.7, 66.9 (Cp), 33.7 (CpCH2), 31.0 (SCH2)
ppm.
stitution can be performed on ferrocenylmethanol instead
of secondary ferrocenyl alcohols, which are favored as they
generate more stable carbenium cations. Finally, our results
provide an unprecedented example of direct-catalyzed OH
substitution of ferrocenylmethanol by diphenylphosphane.
3e: Yield 156 mg, 87%. C21H18FeS (368.28): calcd. C 70.40, H 5.06;
found C 70.27, H 5.13. 1H NMR (CDCl3): δ = 8.01–7.43 (7 H,
C9H7), 4.19 (m, 2 H, Cp), 4.18 (s, 5 H, Cpfree), 4.11 (m, 2 H, Cp),
4.04 (s, 2 H, CpCH2) ppm. 13C NMR (CDCl3): δ = 134.5–125.6
Experimental Section
General: All reactions were routinely performed under a nitrogen
atmosphere by using standard Schlenk techniques. Solvents were
Eur. J. Inorg. Chem. 2013, 3710–3718
3715
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
(Carom), 84.3 (Cipso-Cp), 68.8 (Cpfree), 68.7, 68.0 (Cp), 34.8 (CpCH2)
ppm.
(s, 5 H, Cpfree), 3.98 (m, 2 H, Cp), 3.92 (m, 2 H, Cp), 3.16 (s, 2 H,
CpCH2) ppm. 13C NMR (CDCl3): δ = 138.8–128.3 (Carom), 84.3
(Cipso-Cp), 69.1, 67.3 (Cp), 68.7 (Cpfree), 29.7 (CpCH2) ppm.
3f: Yield 124 mg, 81%. C14H18FeS2 (306.27): calcd. C 54.90, H
1
5.92; found C 54.77, H 5.93. H NMR (CDCl3): δ = 4.18 (m, 2 H,
[Fc–CH2R] (R = C4H3O, 7; R = C4H4N, 8; R = C5H5O2, 9): Com-
plexes 7, 8, and 9 were prepared by the same procedure described
above for 6, by reacting 1(110 mg, 0.51 mmol) with furan, pyrrole,
and 2-furfuryl alcohol, respectively. A longer reaction time (4 h)
was required.
Cp), 4.13 (s, 5 H, Cpfree), 4.12 (m, 2 H, Cp), 3.51 (s, 2 H, CpCH2),
3
3.13 (t, JH,H = 6.5 Hz, 2 H, CH2CH2CH2SH), 2.57 (m, 2 H,
CH2CH2CH2SH), 1.84 (m, 2 H, CH2CH2CH2SH), 1.34 (t, 3JH,H
=
8.1 Hz, 1 H, SH) ppm. 13C NMR (CDCl3): δ = 85.0 (Cipso-Cp), 68.7
(Cpfree), 68.6, 68.0 (Cp), 33.1 (CpCH2), 31.8, 30.1, 23.4
(CH2CH2CH2SH) ppm.
7: Yield 75 mg, 55%. C15H14FeO (266.12): calcd. C 67.70, H 5.30;
found C 67.61, H 5.38. 1H NMR (CDCl3): δ = 7.34 (m, 1 H,
CHfuran), 6.31 (m, 1 H, CHfuran), 6.04 (m, 1 H, CHfuran), 4.13 (m,
2 H, Cp), 4.10 (s, 5 H, Cpfree), 4.08 (m, 2 H, Cp), 3.67 (s, 2 H,
CpCH2) ppm. 13C NMR (CDCl3): δ = 154.9, 140.8, 110.1, 105.4
(Cfuran), 85.4 (Cipso-Cp), 68.7 (Cpfree), 68.4, 67.4 (Cp), 28.4 (CpCH2)
ppm.
3g: Yield 126 mg, 91%. C13H16FeOS (276.18): calcd. C 56.54, H
1
5.84; found C 56.60, H 5.73. H NMR (CDCl3): δ = 4.17 (m, 2 H,
Cp), 4.13 (s, 5 H, Cpfree), 4.12 (m, 2 H, Cp), 3.66 (m, 2 H,
3
CH2CH2OH), 3.52 (s, 2 H, CpCH2), 2.66 (t, JH,H = 6.0 Hz, 2 H,
CH2CH2OH), 2.31 (br, 1 H, OH) ppm. 13C NMR (CDCl3): δ =
84.7 (Cipso-Cp), 68.7 (Cpfree), 68.5, 68.0 (Cp), 60.2 (CH2CH2OH),
34.8 (CH2CH2OH), 31.4 (CpCH2) ppm.
8: Yield 69 mg, 51%. C15H15FeN (265.13): calcd. C 67.95, H 5.70;
found C 67.91, H 5.68. 1H NMR (CDCl3): δ = 7.97 (br. s, NH),
3h: Yield 127 mg, 83%. C14H18FeO2S (306.20): calcd. C 54.91, H
1
5.92; found C 54.77, H 5.99. H NMR (CDCl3): δ = 4.19 (m, 2 H, 6.64 (m, 1 H, CHpyrrole), 6.12 (m, 1 H, CHpyrrole), 5.94 (m, 1 H,
Cp), 4.16 (m, 2 H, Cp), 4.13 (s, 5 H, Cpfree), 3.69 (m, 2 H, CH2OH), CHpyrrole), 4.14 (s, 5 H, Cpfree), 4.12 (m, 1 H, Cp), 4.11 (m, 1 H,
3.55 (s, 2 H, CpCH2), 3.50 (m, 1 H, CHOH), 2.92 (br. s, 1 H, OH), Cp), 3.71 (s, 2 H, CpCH2) ppm. 13C NMR (CDCl3): δ = 129.90
2.60, (m, 2 H, SCH2), 2.40 (br. s, 1 H, OH) ppm. 13C NMR (Cq-pyrrole), 116.05, 108.11, 105.39 (Cpyrrole), 86.6 (Cipso-Cp), 68.7
(CDCl3): δ = 84.6 (Cipso-Cp), 69.9, 68.7 (Cp), 68.8 (Cpfree), 68.1 (Cpfree), 68.5, 67.7 (Cp), 28.1 (CpCH2) ppm.
(CH2OH), 65.4 (CHOH), 35.3 (SCH2), 32.1 (CpCH2) ppm.
9: Yield 121 mg, 80%. C16H16FeO2 (296.14): calcd. C 64.89, H 5.45;
3i: Yield 152 mg, 94%. C17H17FeNS (323.23): calcd. C 63.17, H
found C 64.82, H 5.36. 1H NMR (CDCl3): δ = 7.43 (m, 1 H,
CHfuran), 6.37 (m, 1 H, CHfuran), 6.32 (m, 1 H, CHfuran), 4.42 (s, 2
H, OCH2), 4.33 (s, 2 H, CpCH2), 4.24 (m, 2 H, Cp), 4.16 (m, 2 H,
Cp), 4.13 (s, 5 H, Cpfree) ppm. 13C NMR (CDCl3): δ = 151.9
(Cq-furan), 142.6, 110.1, 109.0 (Cfuran), 82.9 (Cipso-Cp), 69.4 (OCH2),
68.5, 68.0 (Cp), 68.4 (Cpfree), 63.3 (CpCH2) ppm.
1
5.30; found C 63.11, H 5.39. H NMR (CDCl3): δ = 7.31–6.64 (4
H, Ph), 4.26 (br, 2 H, NH2), 4.10 (s, 5 H, Cpfree), 4.08 (m, 2 H,
Cp), 4.04 (m, 2 H, Cp), 3.72 (s, 2 H, CpCH2) ppm. 13C NMR
(CDCl3): δ = 148.4 (Cq-Ph), 136.4–114.9 (Carom), 84.9 (Cipso-Cp), 68.6
(Cp and Cpfree), 68.0 (Cp), 35.7 (CpCH2) ppm.
[Fc–CH2NHR] (R = p-NO2C6H4, 5a; R = p-iPrC6H4, 5b): Com-
pounds 5a–b were prepared by the same procedure described above
for 3a (except for a longer reaction time, 2 h) by reacting 1 with
the appropriate amine. Crystals of 5a suitable for X-ray analysis
were obtained by slow evaporation from a CH2Cl2 solution.
[Fc–CH2-indole] (10): Complex 10 was prepared by the same pro-
cedure as that for the synthesis of 7, 8, and 9 by reacting 1 (110 mg,
0.51 mmol) with indole, yield 118 mg, 75%. C19H17FeN (315.20):
1
calcd. C 72.40, H 5.44; found C 72.52, H 5.38. H NMR (CDCl3):
3
δ = 7.87 (br s, 1 H, NH), 7.62 (d, JH,H = 8.0 Hz, 1 H, CHindole),
3
3
5a: Yield 154 mg, 92%. C17H16FeN2O2 (336.17): calcd. C 60.74, H
7.33 (d, JH,H = 8.0 Hz, 1 H, CHindole), 7.18 (t, JH,H = 7.2 Hz, 1
1
3
3
4.80; found C 60.77, H 4.89. H NMR (CDCl3): δ = 8.10 (d, JH,H
H, CHindole), 7.11 (t, JH,H = 7.2 Hz, 1 H, CHindole), 6.87 (s, 1 H,
3
= 8.0 Hz, 2 H, Ph), 6.56 (d, JH,H = 8.0 Hz, 2 H, Ph), 4.76 (br., 1
CHindole), 4.20 (m, 2 H, Cp), 4.16 (s, 5 H, Cpfree), 4.08 (m, 2 H,
Cp), 3.85 (s, 2 H, CpCH2) ppm. 13C NMR (CDCl3): δ = 136.2,
127.3 (Cq-indole), 121.9, 121.6, 119.2, 118.94, 116.83, 111.03 (Cindole),
85.0 (Cipso-Cp), 68.7, 67.2 (Cp), 68.6 (Cpfree), 25.5 (CpCH2) ppm.
H, NH), 4.24 (m, 2 H, Cp), 4.20 (s, 5 H, Cpfree), 4.19 (m, 2 H, Cp),
3
4.06 (d, JHH = 5.0 Hz, 2 H, CpCH2) ppm. 13C NMR (CDCl3): δ
= 152.9 (Cipso-Ph), 138.0, 126.5, 111.0 (Carom), 84.4 (Cipso-Cp), 68.6
(Cpfree), 68.4, 68.2 (Cp), 42.9 (CpCH2) ppm.
X-ray Crystallography: The crystal data and collection details for
3b and 5a are reported in Table 6. The asymmetric units of both
crystals contain two independent molecules with almost identical
geometries and bonding parameters. The diffraction experiments
were performed with a Bruker APEX II diffractometer equipped
with a CCD detector by using Mo–Kα radiation. The data were
corrected for Lorentz polarization and absorption effects (empiri-
cal absorption correction SADABS).[35] Structures were solved by
direct methods and refined by full-matrix least-squares on F2 (all
data).[36] All non-hydrogen atoms were refined with anisotropic dis-
placement parameters. All hydrogen atoms were fixed at calculated
positions and refined by using a riding model, except for the N–H
groups in 5a, which were located in the Fourier map and refined
isotropically by using 1.2 times the Uiso value of the parent N atom.
Similar U restraints (standard uncertainty 0.01) were applied to all
C atoms. One Cp ring of one of the two independent molecules of
5a is disordered and, thus, it has been split into two images and
refined with one occupancy parameter. The H atoms were placed
5b: Yield 143 mg, 86%. C20H23FeN (333.25): calcd. C 72.08, H
1
3
6.96; found C 71.99, H 5.89. H NMR (CDCl3): δ = 7.08 (d, JH,H
3
= 8.0 Hz, 2 H, Ph), 6.63 (m, JH,H = 8.0 Hz, 2 H, Ph), 4.25 (m, 2
H, Cp), 4.18 (s, 5 H, Cpfree), 4.14 (m, 2 H, Cp), 3.95 (s, 2 H,
3
CpCH2), 3.79 (br., 1 H, NH), 2.83 (sept, JH,H = 6.9 Hz, 1 H,
3
CH3CHCH3), 1.22 (d, JH,H = 6.9 Hz, 6 H, CH3) ppm. 13C NMR
(CDCl3): δ = 146.4, 138.1, 127.1, 112.9 (Carom), 86.7 (Cipso-Cp), 68.5
(Cpfree), 68.1, 67.8 (Cp), 43.7 (CpCH2), 33.2 (CH3CHCH3), 24.3
(CH3) ppm.
[Fc–CH2PPh2] (6): A solution of 1 (110 mg, 0.51 mmol) in CH2Cl2
(20 mL) was treated with diphenylphosphane (142 mg, 0.76 mmol)
in the presence of [Fp][OTf] (0.05 mmol). The resulting mixture
was stirred at room temperature for 2 h. After solvent removal and
chromatography of the residue on alumina with petroleum ether
(b.p. 40–60 °C) as eluent, 6 was obtained in the first yellow fraction
(80 mg, 41%), followed by a second orange fraction containing 4
(74 mg, 36%). C23H21FeP (384.23): calcd. C 71.90, H 5.51; found
C 71.81, H 5.39. 1H NMR (CDCl3): δ = 7.50–7.29 (10 H, Ph), 4.10 in calculated positions and treated isotropically.
Eur. J. Inorg. Chem. 2013, 3710–3718
3716
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
[10] a) X. Xu, R. Jiang, X. Zhou, Y. Liu, S. Ji, Y. Zhang, Tetrahe-
dron 2009, 65, 877–882; b) R. Jiang, Y. Zhang, Y. C. Shen, X.
Zhu, X. P. Xu, S. J. Ji, Tetrahedron 2010, 66, 4073–4078.
[11] a) P. G. Cozzi, L. Zoli, Green Chem. 2007, 9, 1292–1295; b)
P. G. Cozzi, L. Zoli, Angew. Chem. 2008, 120, 4230; Angew.
Chem. Int. Ed. 2008, 47, 4162–4166.
[12] a) A. Togni, T. Hayashi, Ferrocenes: Homogeneous Catalysis,
Organic Synthesis Materials Science, Wiley-VCH, Weinheim,
Germany, 1995; b) P. Stepnicka, Ferrocenes: Ligands, Materials
and Biomolecules, Wiley, Chichester, 2008.
Table 6. Crystal data and experimental details for 3b and 5a.
3b
5a
Formula
Fw
C17H16FeS
308.21
C17H16FeN2O2
336.17
T [K]
295(2)
295(2)
λ [Å]
0.71073
triclinic
P1
0.71073
Crystal system
Space group
a [Å]
b [Å]
c [Å]
triclinic
¯
¯
P1
9.830(2)
13.265(3)
13.613(5)
113.050(4)
99.908(4)
108.921(3)
1451.0(7)
4
11.2600(12)
12.9225(14)
12.9652(14)
65.7970(10)
70.5980(10)
65.3390(10)
1533.9(3)
4
[13] L. Busetto, R. Mazzoni, M. Salmi, S. Zacchini, V. Zanotti,
RSC Adv. 2012, 2, 6810–6816.
[14] Selected examples include: a) Iron Catalysis in Organic Chemis-
try (Eds: B. Plietker) Wiley-VCH, Weinheim 2008; b) A. Cor-
rea, O. G. Mancheño, C. Bolm, Chem. Soc. Rev. 2008, 37,
1108–1117; c) B. D. Sherry, A. Fürstner, Acc. Chem. Res. 2008,
41, 1500–1511; d) R. M. Bullock, Angew. Chem. 2007, 119,
7504; Angew. Chem. Int. Ed. 2007, 46, 7360–7363; e) G. Cahiez,
V. Habiak, C. Duplais, A. Moyeux, Angew. Chem. 2007, 119,
4442; Angew. Chem. Int. Ed. 2007, 46, 4364–4366; f) S. Entha-
ler, K. Junge, M. Beller, Angew. Chem. 2008, 120, 3363; Angew.
Chem. Int. Ed. 2008, 47, 3317–3321; g) R. Mazzoni, M. Salmi,
V. Zanotti, Chem. Eur. J. 2012, 18, 10174–10194.
α[°]
β [°]
γ [°]
Cell volume [Å3]
Z
σcalcd. [gcm–3]
μ [mm–1]
F(000)
1.411
1.165
640
1.456
0.991
696
Crystal size [mm]
θ limits [°]
Reflections collected
Independent reflections
0.16ϫ0.14ϫ0.10 0.25ϫ0.44ϫ0.18
1.73–26.00
15138
1.76–26.00
15667
[15]
[16]
[17]
[18]
[19]
[20]
C. S. Combs, C. I. Ashmore, A. F. Bridges, C. R. Swanson,
W. D. Stephens, J. Org. Chem. 1969, 34, 1511–1512.
B. Misterkiewicz, C. Kajdas, M. Dominiak, J. Dabrowski, J.
Wasilewski, Chem. Ind. 1981, 12, 433–434.
M. Uher, S. Toma, Collection Czechoslov. Chem. Commun.
1971, 36, 3056–3059.
B. Czech, A. Czech, S. I. Kang, R. A. Bartsch, Chem. Lett.
1984, 37–40.
N. Oda, T. Ueda, I. Ito, Chem. Pharm. Bull. 1979, 27, 2855–
2857.
a) T. Kondo, Y. Morisaki, S. Y. Uenoyama, K. Wada, T. A.
Mitsudo, J. Am. Chem. Soc. 1999, 121, 8657–8658; b) A. B.
Zaitsev, H. F. Caldwell, P. S. Pregosin, L. F. Veiros, Chem. Eur.
J. 2009, 15, 6468–6477; c) P. Jaisankar, S. Tanaka, M. Kita-
mura, J. Org. Chem. 2011, 76, 1894–1897.
5676
5977
[Rint = 0.0257]
5676/204/343
1.018
[Rint = 0.0200]
5977/322/449
1.037
Data/restraints/parameters
Goodness of fit on F2
R1 [IϾ2σ(I)]
0.0349
0.0318
wR2 (all data)
0.0892
0.482/–0.193
0.0878
0.349/–0.197
Largest diff. peak and hole [eÅ–3]
Acknowledgments
The authors thank the Ministero dell’Istruzione, dell’Università e
della Ricerca (MIUR), PRIN 09 project: Designing metal contain-
ing molecular fragments for advanced chemical applications) and
the University of Bologna for financial support.
[21]
[22]
R. Jiang, X.-Q. Chu, X.-P. Xu, B. Wu, S.-J. Ji, Aust. J. Chem.
2011, 64, 1530–1537.
a) M. Ahmad, R. Bruce, G. R. Knox, J. Organomet. Chem.
1966, 6, 1–10; b) D. G. McGuire, M. A. Khan, M. T. Ashby,
Inorg. Chem. 2002, 41, 2202–2208.
[1] a) I. T. Horvath, P. T. Anastas, Chem. Rev. 2007, 107, 2169–
2173; b) R. A. Sheldon, Chem. Soc. Rev. 2012, 41, 1437–1451;
c) P. T. Anastas, M. M. Kirchhoff, Acc. Chem. Res. 2002, 35,
686–694.
[2] for a recent review article see: B. Sundararaju, M. Achard, C.
Bruneau, Chem. Soc. Rev. 2012, 41, 4467–4483.
[3] a) H. Hikawa, Y. Ino, H. Suzuki, Y. Yokoyama, J. Org. Chem.
2012, 77, 7046–7051; b) K. J. Miller, M. M. Abu-Omar, Eur. J.
Org. Chem. 2003, 1294–1299.
[4] a) Y. Nishibayashi, M. Yoshikawa, Y. Inada, M. Hidai, S. Ue-
mura, J. Am. Chem. Soc. 2002, 124, 11846–11847; b) Y. Nishi-
bayashi, H. Imajima, G. Onodera, M. Hidai, S. Uemura, Orga-
nometallics 2004, 23, 26–30; c) Y. Nishibayashi, M. D. Milton,
Y. Inada, M. Yoshikawa, I. Wakiji, M. Hidai, S. Uemura,
Chem. Eur. J. 2005, 11, 1433–1451; d) Y. Inada, Y. Nishibaya-
shi, S. Uemura, Angew. Chem. 2005, 117, 7893; Angew. Chem.
Int. Ed. 2005, 44, 7715–7717; e) V. Cadierno, J. Díez, S. E.
García-Garrido, J. Gimeno, Chem. Commun. 2004, 2716–2717;
f) E. Bustelo, P. H. Dixneuf, Adv. Synth. Catal. 2005, 347, 393–
397.
[5] B. Biannic, A. Aponick, Eur. J. Org. Chem. 2011, 6605–6617.
[6] H. Mayr, B. Kempf, A. R. Ofial, Acc. Chem. Res. 2003, 36, 66–
77.
[7] P. Vicennati, P. G. Cozzi, Eur. J. Org. Chem. 2007, 2248–2253.
[8] R. Jiang, Y. Shen, Y. Zhang, X. Xu, J. Shao, S. Ji, Chin. J.
Chem. 2011, 29, 1887–1893.
[23]
[24]
P. M. Treichel, L. D. Rosenhein, Inorg. Chem. 1981, 20, 942–
944.
a) G. Guillena, D. J. Ramon, M. Yus, Chem. Rev. 2010, 110,
1611–1641; b) G. E. Dobereiner, R. H. Crabtree, Chem. Rev.
2010, 110, 681–703.
[25]
[26]
C. M. M’thiruaine, H. B. Friedrich, E. O. Changamu, M. D.
Bala, Inorg. Chim. Acta 2011, 336, 105–115.
M. E. Dudley, Md. M. Morshed, C. L. Brennan, M. S. Islam,
M. S. Ahmad, M.-R. Atuu, B. Branstetter, M. M. Hossain, J.
Org. Chem. 2004, 69, 7599–7608.
[27]
[28]
N. J. Goodwin, W. Henderson, B. K. Nicholson, J. Fawcett,
D. R. Russell, J. Chem. Soc., Dalton Trans. 1999, 1785–1793.
N. J. Goodwin, W. Henderson, B. K. Nicholson, J. K. Sarfo, J.
Fawcett, D. R. Russell, J. Chem. Soc., Dalton Trans. 1997,
4377–4384.
[29]
[30]
T. V. V. Ramakrishna, A. J. Elia, A. Vij, J. Organomet. Chem.
2000, 602, 125–132.
a) A. Togni, C. Breutel, A. Schnyder, F. Spindler, H. Landert,
A. Tijani, J. Am. Chem. Soc. 1994, 116, 4062–4066; b) A.
Togni, Angew. Chem. 1996, 108, 1581; Angew. Chem. Int. Ed.
Engl. 1996, 35, 1475–1477.
[31]
[32]
a) I. R. Butler, Eur. J. Inorg. Chem. 2012, 4387–4406; b) P. Bar-
baro, C. Bianchini, G. Giambastiani, S. L. Parisel, Coord.
Chem. Rev. 2004, 248, 2131–2150; c) A. Fihri, P. Meunier, J. C.
Hierso, Coord. Chem. Rev. 2007, 251, 2017–2055.
a) R. Schuecker, W. Weissensteiner, K. Mereiter, M. Lotz, F.
Spindler, Organometallics 2010, 29, 6443–6458; b) R. J. Kloetz-
[9] R. Jiang, X.-P. Xu, T. Chen, H.-Y. Li, G. Chen, S.-J. Ji, Synlett
2009, 17, 2815–2820.
Eur. J. Inorg. Chem. 2013, 3710–3718
3717
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
ing, M. Lotz, P. Knochel, Tetrahedron: Asymmetry 2003, 14,
255–264.
[33] a) W. Malisch, K. Thirase, F.-J. Rehmann, J. Reising, N. Gun-
zelmann, Eur. J. Inorg. Chem. 1998, 1589–1595; b) J. Powell, E.
Fuchs, M. R. Gregg, J. Phillips, M. V. R. Stainer, Organometal-
lics 1990, 9, 387–393; c) H. Nakazawa, Y. Ueda, K. Nakamura,
K. Miyoshi, Organometallics 1997, 16, 1562–1566.
[34] H. Nakazawa, K. Kubo, C. Kai, K. Miyoshi, J. Organomet.
Chem. 1992, 439, C42–C45.
[35] G. M. Sheldrick, SADABS, Program for empirical absorption
correction, University of Göttingen, Germany, 1996.
[36] G. M. Sheldrick, SHELX97, Program for crystal structure de-
termination, University of Göttingen, Germany, 1997.
Received: February 19, 2013
Published Online: June 19, 2013
Eur. J. Inorg. Chem. 2013, 3710–3718
3718
© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim