Lithiated dimethylaminomethyl ferrocenes and ruthenocenes

Article abstract of DOI:10.1016/j.jorganchem.2005.10.034

Dimethylaminomethylferrocenyl lithium and -ruthenocenyl lithium were generated using tin/lithium exchange reactions. The four different metallocenyl lithium compounds were analysed using NMR spectroscopy. The metallocenyl lithium reagents are useful reage

Full text of DOI:10.1016/j.jorganchem.2005.10.034

Journal of Organometallic Chemistry 691 (2006) 916–920
www.elsevier.com/locate/jorganchem
Lithiated dimethylaminomethyl ferrocenes and ruthenocenes
a,b,
a,
b
Reinout Meijboom
*, Paul Beagley a,1, John R. Moss *, Andreas Roodt
a
Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
b
Received 19 September 2005; received in revised form 10 October 2005; accepted 21 October 2005
Available online 6 December 2005
Abstract
Dimethylaminomethylferrocenyl lithium and -ruthenocenyl lithium were generated using tin/lithium exchange reactions. The four dif-
ferent metallocenyl lithium compounds were analysed using NMR spectroscopy. The metallocenyl lithium reagents are useful reagents
and have been shown to react with MeOD, ClSiMe3 and DMF to give air-stable derivatives.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Lithium; Ferrocene; Ruthenocene; Tin/lithium exchange
1. Introduction
Previously, we have isolated polylithiated carbosilanes of
the type Si[(CH2)3SiMe2CH2Li]4 by treating Si[(CH2)3Si-
Me2CH2SnBu3]4 with n-BuLi in tetrahydrofuran (thf) at
ꢀ78 ꢁC; the Bu4Sn byproduct was removed by successive
washes with pentane [7]. We have now adopted this meth-
odology to isolate 3a, 3b and 6a, 6b, since the ferrocenyl or
ruthenocenyl stannanes are readily prepared and the C–Sn
bond can be cleaved quantitatively to yield the appropriate
lithiated metallocene.
Lithiated ferrocenes and ruthenocenes are useful syn-
thetic reagents in organometallic chemistry. We have
recently utilised 2- and 10-(dimethylaminomethyl)-1-(lith-
ium)-ferrocenides 3a and 6a [1] and the corresponding
ruthenocenides 3b and 6b [2] in the synthesis of organome-
tallic chloroquine analogues (see Scheme 1). A monomeric
deprotonating agent seems to be essential for the metalla-
tion of ferrocenes to be carried out smoothly and in high
yield [3]. The lithiation of N,N-dimethylaminomethylferro-
cene (1a) [4] is fast (ca. 1 h with n-BuLi in diethyl ether) and
clean [5]. No X-ray structural analysis has so far been car-
ried out, but the structure probably involves chelation of
the carbon-2-bound lithium with the amine nitrogen as
related structures show this chelation [6]. In contrast to
the lithiation of 1a, the ruthenium analogue 1b gives under
similar conditions a mixture of 1,2- and 1,10-(dimethylam-
inomethyl)-(lithium)-ruthenocenides [2]. This spurred us on
to find a methodology to cleanly generate either the 2- or
the 10-(dimethylaminomethyl)-1-(lithium)-metallocenides.
2. Results and discussion
2.1. Isolation of 3a, 3b and 6a, 6b
Though 2-(dimethylaminomethyl)-1-(lithium)-ferroce-
nide, 3a, has previously been isolated [8], it has not been
1
characterised by H and 13C NMR before. We have now
used a modified version of the Rausch procedure to isolate
3a directly from the parent compound N,N-dimethylami-
nomethylferrocene, 1a. In addition we have isolated lith-
ium ferrocenide 3a from the corresponding stannane 2a.
Interestingly, ferrocenide 3a precipitated out of solution
when commercial samples of N,N-dimethylaminomethyl-
ferrocene 1a were used but not when ‘‘home-made’’ sam-
ples of either 1a or 2a were utilised. Since commercial
samples of 1a contain trace quantities of ferrocene (TLC
*
Corresponding authors. Tel.: +27 51 4019526; fax: +27 51 4446384.
E-mail addresses: meijboomr.sci@mail.uovs.ac.za (R. Meijboom),
jrm@science.uct.ac.za (J.R. Moss).
1
Present address: Peakdale Molecular Ltd., High Peak, SK23 0PG, UK.
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.10.034

R. Meijboom et al. / Journal of Organometallic Chemistry 691 (2006) 916–920
917
Bu3Sn
N
N
N
Li
ClSnBu3
tert-BuLi
Et2O
M
M
M
1a: M = Fe
1b: M = Ru
3a: M = Fe
3b: M = Ru
2a: M = Fe
2b: M = Ru
N
N
Li
ClSnBu3
n-BuLi
pentane
1b
Ru
Ru
SnBu3
5b
6b
SnBu3
N
n-BuLi, thf, -78 oC
(H2C=NMe2)I
Fe
Fe
SnBu3
SnBu3
4a
5a
Scheme 1. Synthesis of 2- and 10-(dimethylaminomethyl)-1-ferrocene and -ruthenocene.
1
Bu3Sn
and H NMR), we suspect that lithium-ferrocenide pro-
vides a nucleation site for the co-precipitation of 3a.
The new compounds 3b, 6a and 6b were isolated from
the corresponding tri-n-butylstannanes 2b, 5a and 5b. The
preparations of the tri-n-butylstannane starting materials
are shown in Scheme 1. The ruthenocene complex 1b was
selectively lithiated and reacted with tri-n-butylstannylchlo-
ride to give the new compounds 2b or 5b, depending on the
deprotonation reagent and solvent. Compound 5a [1,9],
was prepared from 1,10-bis(tri-n-butylstannyl)ferrocene,
4a (see Scheme 1) using a tin/lithium exchange reaction
using one molar equivalent of n-butyllithium, followed by
reaction with EschenmoserÕs salt.
N
Li
N
n-BuLi, thf, -78 oC
M
M
2a: M = Fe
2b: M = Ru
3a: M = Fe
3b: M = Ru
N
N
o
n-BuLi, thf, -78 C
M
M
SnBu3
Li
The corresponding 2- and 10-(dimethylaminomethyl)-1-
(lithium)-metallocenides (3 and 6) were prepared and iso-
lated from the corresponding tri-n-butyltin complexes 2
and 5. The tin/lithium exchange reaction proceeds fast
and quantitative at ꢀ78 ꢁC in thf. The reaction had to be
performed in the relatively strongly coordinating, and reac-
tive solvent thf, in order to stabilise the penta-substituted
stannate that is proposed as an intermediate for this type
of reaction [10]. The complexes 6a and 6b can be isolated
as air- and moisture sensitive solids by successive washes
with pentane. The compounds 3a and 3b appeared to be
soluble in pentane. They could not be separated from the
Bu4Sn byproduct and were analysed as a mixture of 3
and Bu4Sn. Unfortunately, we were unable to grow crystals
suitable for X-ray diffraction analysis (see Scheme 2).
As far as we are aware, the synthesis and characterisa-
tion of 10-(dimethylaminomethyl)-1-(lithium)-ferrocenide
(6a) and -ruthenocenide (6b) have not been reported
5a: M = Fe
5b: M = Ru
6a: M = Fe
6b: M = Ru
Scheme 2. Isolation of 2- and 10-(dimethylaminomethyl)-1-(lithium)
metallocenides of iron and ruthenium.
before. The lithiation of metallocenes using tin/lithium
exchange reactions is not a new route [9], but it has not
been fully explored yet. The tin/lithium exchange reaction
appears to be a powerful tool to functionalise metallocenes
and, despite the incorporation of strongly ortho-directing
groups such as –CH2NMe2, this functionalisation can be
performed at any predetermined position. The presence
of the –CH2NMe2 functionality in the starting material
suggests that the here described route might also be suc-
cessful in the presence of other coordinating functionalities,
such as ethers, thioethers, etc.

918
R. Meijboom et al. / Journal of Organometallic Chemistry 691 (2006) 916–920
D
N
N
MeOD
MeOD
M
M
D
7a: M = Fe
7b: M = Ru
8a: M = Fe
8b: M = Ru
Me3Si
N
N
N
N
Li
ClSiMe3
ClSiMe3
M
M
M
M
Li
SiMe3
3a: M = F e
3b: M = Ru
9a: M = Fe
9b: M = Ru
6a: M = Fe
6b: M = Ru
10a: M = Fe
10b: M = Ru
N
N
O
O
1) DMF
2) H2O
1) DMF
2) H2O
M
M
11a: M = F e
11b: M = Ru
12a: M = Fe
12b: M = Ru
Scheme 3. Reactions of 3 to form 7, 9 and 11 and 6 to form 8, 10 and 12.
Complete lithiation of the metallocenes 3a, 3b, 6a and 6b
mann grade I) and distilled from sodium/benzophenone
ketyl prior to use [13]. All reagents were stored under
argon. All reagents were purchased from Sigma–Aldrich.
N,N-Dimethylaminomethylferrocene [2] and 10-dimethy-
laminomethyl-1-tri-n-butylstannyl ferrocene [1] (5a) were
prepared according to the literature methods.
was confirmed by quenching the complex in CH3OD and
analyses of the products by NMR spectroscopy (7a, 7b,
8a and 8b). In addition, the lithiated metallocenes were
reacted with ClSiMe3 to give the corresponding silanes
(9a, 9b, 10a and 10b). The lithiated metallocenes were also
reacted with DMF to give the corresponding carbaldehy-
des (after quenching the reaction with H2O) 11a, 11b, 12a
and 12b. The latter compounds were reported previously
(11a: [11], 12a: [1], 11b and 12b: [2]), though they were iso-
lated using a different synthetic route. The analytical data
of the latter compounds were identical to the previously
reported data (see Scheme 3).
NMR spectra were recorded on either a Varian Unity-
400 (1H: 400 MHz; 13C: 100.6 MHz; 29Si: 79.5 MHz) spec-
trometer or a Varian Mercury-300 (1H: 300 MHz; 13C:
75.5 MHz) spectrometer at ambient temperature. Chemical
shifts were referenced to TMS using either the residual pro-
ton impurities in the solvent (1H NMR), the solvent reso-
nances (13C NMR) or external TMS (29Si NMR).
Infrared spectra were recorded on a Perkin–Elmer Paragon
3. Conclusions
1000 FT-IR spectrometer in the range 450–4400 cmꢀ1
.
Spectra were recorded on neat samples between NaCl
plates. Mass spectra were determined by Dr. P. Boshoff
of the mass spectrometry unit at the Cape Technikon.
The selected m/z values given refer to the isotopes 1H,
12C, 14N, 28Si, 102Ru and 120Sn. In all cases, the isotopic
distribution pattern was checked against the theoretical
distribution. Elemental analyses were performed using a
Carlo Erba EA1108 elemental analyser in the microanalyt-
ical laboratory of the University of Cape Town.
We describe a new and versatile route to the synthesis
and characterisation of lithiated metallocenes of iron and
ruthenium. Key to this route is the tin/lithium exchange
reaction in tetrahydrofuran. The tin/lithium exchange
allows lithiation of metallocenes at predetermined sites,
in the presence of the strongly ortho-directing dimethylam-
inomethyl functionality. We expect that this synthetic route
will also be successful in the presence of other coordinating
groups. Several derivatives of the lithiated metallocenes
have been isolated and characterised in high (>90%) yield.
4.2. Dimethylaminomethyl-tri-n-butylstannyl metallocenes
4. Experimental
4.2.1. 2-Dimethylaminomethyl-1-tri-n-butylstannyl ferrocene
(2a)
4.1. General remarks
t-BuLi (4.4 cm3, of a 1.4 M solution in pentane,
6.2 mmol) was added to a solution of N,N-dimethylami-
nomethylferrocene (1 g, 4.1 mmol) in diethyl ether
(75 cm3) and stirred for 0.5 h. n-Bu3SnCl (1.68 cm3,
6.2 mmol) was added and the mixture was stirred for 3 h.
Water (20 cm3) was added and the organic phase removed,
the aqueous phase was washed with diethyl ether
Lithiated metallocenes are extremely air-sensitive com-
pounds. Manipulations were carried out under purified
nitrogen using glovebox (MBraun Unilab) or standard
Schlenk-line techniques [12]. Solvents were dried by pas-
sage through a column containing alumina (neutral, Brock-

R. Meijboom et al. / Journal of Organometallic Chemistry 691 (2006) 916–920
919
(2 · 15 cm3), the organic fractions were combined, dried
over Na2SO4, filtered and the solvent removed in vacuo.
The crude product was purified by column chromatogra-
phy on alumina (Brockman V) eluting with hexane–diethyl
ether–triethylamine 70:29:1; as an orange oil (1.94 g, 89%)
(Found: C, 56.20; H, 8.02; N, 2.58%. FeSnC25H43N calcu-
lated C, 56.42; H, 8.14; N, 2.63%); ~mmax=cmꢀ1 3094m,
2955s, 2926s, 2852s, 2812s, 2762s, 1457s, 1375m, 1342m,
1260m, 1174m, 1130m, 1106m, 1069m, 1023s, 1000m,
960m, 845m, 816m, 665m, 597m, 597m, 487m, 458w,
414m neat (NaCl); dH(C6D6; 400 MHz) 4.15 (1H, m),
4.13 (1H, m), 4.00 (5H, s), 3.99 (1H, m), 3.53 [1H, d,
2923s, 2856s, 2850s, 2810s, 2758s, 1457s, 1375m, 1344m,
1257m, 1168m, 1132m, 1018s, 959m, 841m, 806s, 688m,
668m, 592m, 492m, 444m neat (NaCl); dH(C6D6;
300 MHz) 4.61–4.65 (4H, m), 4.47 (2H, m), 4.40 (2H, m),
3.15 (2H, s), 3.17 (6H, s), 1.56–1.69 (6H, m), 1.31–1.45
(6H, m) 0.90–1.05 (15H, m); dC(C6D6; 75 MHz) 88.0
(ipso-Cp), 77.0, 73.3, 72.8 (Cp), 71.2 (ipso-Cp), 70.4 (Cp),
56.6 (CH2N), 44.9 (NMe2), 29.6 [3J(CCC117/119Sn)
20 Hz], 27.8 [2J(CCSn117/119) 58 Hz], 13.9 (Me), 10.9
[1J(C117/119Sn) 348/332 Hz]; MS (FAB): m/z 578 (23%,
n
M+ ꢀ H), 535 (75, M+ ꢀ NMe2), 522 (64, M+ ꢀ Bu),
n
478 (37, M+ ꢀ Bu ꢀ NMe2), 407 (33, M+ ꢀ 3nBu), 364
2J(HH) 12 Hz], 2.69 [1H, d, J(HH) 12 Hz], 2.01 (6H, s),
(79, M+ ꢀ 3nBu ꢀ NMe2), 288 (24, M+ ꢀ SnnBu3), 244
(100, M+ ꢀ NMe2 ꢀ SnnBu3).
2
1.64–1.75 (6H, m), 1.37–1.48 (6H, m), 1.13–1.19 (6H, m),
3
0.95 [9H, t, J(HH) 7 Hz]; dC(C6D6; 100 MHz) 91.0, 80.3
(ipso-Cp), 75.4, 72.7, 69.8, 68.8 (Cp), 60.8 (CH2N),
44.9 (NMe2), 29.7, [3J(CCC117/119Sn) 18 Hz], 27.8
[2J(CC117/119Sn) 59 Hz], 13.8, 10.8 [1J(C117/119Sn) 349/334 Hz].
4.3. Dimethylaminomethyl lithium metallocenides
The synthesis of the lithium metallocenides is similar for
all compounds. A representative example is given below.
4.2.2. 2-Dimethylaminomethyl-1-tri-n-butylstannyl
ruthenocene (2b)
4.3.1. NMR scale synthesis of 10-dimethylaminomethyl-1-
lithiumferrocenide (6a)
Prepared by an analogous method to 2a and obtained as
a yellow oil. Yield: 85%; (Found: C, 52.21; H, 7.79; N,
2.21%. RuSnC25H43N calculated C, 52.00; H, 7.51; N,
A Teflon valved NMR tube was loaded with of 10-dime-
thylaminomethyl-1-tri-n-butylstannylferrocene (71.1 mg,
2.42%); mmax=cmꢀ1 3094m, 2950s, 2918s, 2856s, 2848s,
~
n
0.13 mmol). BuLi in hexanes (86 mm3, 1.6 M, 0.13 mmol)
2810, 2761s, 1455s, 1376m, 1341m, 1258m, 1171m,
1128m, 1101m, 1070m, 1020m, 996m, 842m, 805s, 686m,
668m, 593m, 504m, 414m neat (NaCl); dH(C6D6;
400 MHz) 4.65 (1H, m), 4.55 (1H, m), 4.45 (5H, s), 4.39
was added, followed by THF (1.0 cm3). Immediately a yel-
low precipitate was observed to form. After shaking the
NMR tube for several minutes the volatiles were removed
in vacuo and the remaining solid was dissolved in C6D6. 1H
NMR confirmed the quantitative formation of the 10-dime-
thylaminomethyl-1-lithiumferrocenide-THF adduct.
dH(C6D6, 400 MHz): 4.55 (s, 2H, Cp), 4.17 (s, 2H, Cp),
4.10 (s, 2H, Cp), 3.85 (s, 2H, Cp), 3.55 (m, 4H, a-THF),
2.69 (s, 2H, CH2N), 2.02 (s, 6H, 2CH3), 1.42 (s, 4H, b-
THF), 1.52 (m, 8 H), 1.32 (m, 8H) and 0.88 (m, 16H)
(SnnBu4); dC(C6D6; 75 MHz) 83.6, 80.6 (ipso-Cp), 72.1,
67.3, 67.1 (Cp), 58.6 (CH2N), 47.0 (NMe2).
2
2
(1H, m), 3.36 [1H, d, J(HH) 12 Hz], 2.63 [1H, d, J(HH)
12 Hz], 2.06 (6H, s), 1.55–1.75 (6H, m), 1.30–1.48 (6H,
m), 1.10–1.18 (6H, m), 0.94 [9H, t, 3J(HH) 7 Hz]; dC(C6D6;
100 MHz) 94.8, 77.2 (ipso-Cp), 75.1, 72.0, 70.8 (Cp), 60.6
(CH2N), 44.9 (NMe2), 29.7 [3J(CCC117/119Sn) 18 Hz],
27.8 [2J(CC117/119Sn) 59 Hz], 13.8, 11.0 [1J(C117/119Sn)
349/334 Hz]; MS (FAB): m/z 578 (23%, M+ ꢀ H),
n
535 (44, M+ ꢀ NMe2), 522 (65, M+ ꢀ Bu), 478 (46,
n
M+ ꢀ Bu ꢀ NMe2), 407 (52, M+ ꢀ 3nBu), 364 (85,
M+ ꢀ 3nBu ꢀ NMe2), 288 (34, M+ ꢀ SnnBu3), 244 (100,
M+ ꢀ NMe2 ꢀ SnnBu3).
4.3.2. NMR scale synthesis of 10-dimethylaminomethyl-1-
lithiumruthenocenide (6b)
4.2.3. 10-Dimethylaminomethyl-1-tri-n-butylstannyl
ruthenocene (5b)
A similar procedure to the NMR scale synthesis of 6a
1
was used. H NMR confirmed the quantitative formation
n-BuLi (1.9 cm3, 3 mmol, of a 1.6 M solution in hex-
anes) was added to a mixture of dimethylaminomethylru-
thenocene (789 mg, 2.7 mmol) in pentane (50 cm3) and
stirred overnight n-Bu3SnCl (0.82 cm3, 3 mmol) was added
and the mixture was stirred for 3 h. Water (20 cm3) was
added and the organic phase removed, the aqueous phase
was washed with diethyl ether (2 · 15 cm3), the organic
fractions were combined, dried over Na2SO4, filtered and
the solvent removed in vacuo. The crude product was puri-
fied by column chromatography on alumina (Brockman
IV) eluting with hexane–diethyl ether–triethylamine
70:29:1; as a light yellow liquid (602 mg, 39%); (Found:
C, 52.17; H, 7.45; N, 2.40%. RuSnC25H43N calculated C,
of the 10-dimethylaminomethyl-1-lithiumruthenocenide-
THF adduct.
dH(C6D6, 400 MHz): 4.84 (s, 2H), 4.57 (m, 2H), 4.48 (s,
2H), 4.38 (s, 2H), 4.25 (s, 1H), 2.5 (m, 4H, a-THF), 2.70 (s,
2H, CH2N), 2.05 (2, 6H, 2 CH3), 1.43 (m, 4H, b-THF),
1.49 (m, 8H), 1.29 (m, 8H) and 0.86 (m, 16H) (SnnBu4);
dC(C6D6; 100 MHz): 82.3, 77.0, 72.6, 71.5, 68.2 (Cp), 67.7
(THF), 57.0 (CH2N), 46.1 (CH3), 25.5 (THF), 29.5, 27.6,
13.6, 8.9 (SnnBu4).
4.4. Reactions of the lithium salts
The NMR scale synthesis of derivatives of the dimethy-
laminomethyl-1-(lithium)-metallocenide reagents were all
52.00; H, 7.51; N, 2.42%); mmax=cmꢀ1 3085m, 2953s,
~

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R. Meijboom et al. / Journal of Organometallic Chemistry 691 (2006) 916–920
performed in a similar method. A representative example is
given.
ing to the ÔbutyllithiumÕ leg and distilling the solvent onto
the lithiated ferrocene. The volatiles were removed in vacuo
to leave a red solid 6a in the one leg and a red oil
(SnBu4 + BuLi + unreacted traces of starting material) in
the other. A solution of N,N-dimethylformamide in THF
was added to the 6a at ꢀ78 ꢁC and the mixture was allowed
to attain room temperature while stirring. Evaporation of
the solvent in vacuo and extraction into pentane gave 11a
in quantitative yield.
4.4.1. NMR scale synthesis of 10-dimethylamino-
methylferrocene-1-carboxaldehyde
A Teflon valved NMR tube was loaded with of 10-(dime-
thylaminomethyl)-1-(tri-n-butylstannyl)ferrocene (71.1 mg).
n-Butyllithium in hexanes (100 m3, 1.6 M) was added, fol-
lowed by THF (1.0 cm3). Immediately a yellow precipitate
was observed to form. After shaking the NMR tube for sev-
eral minutes the volatiles were removed in vacuo and the
remaining solid was dissolved in C6D6. 1H NMR confirmed
the quantitative formation of the 10-(dimethylaminom-
ethyl)-1-(lithium)ferrocenide-THF adduct.
Acknowledgements
Financial assistance from the South African National
Research Foundation (NRF) and the Research Fund of
the Universities of Cape Town and the Free State is grate-
fully acknowledged. The Claude Harris Leon Foundation
is thanked for a post-doctoral fellowship for P.B. Part of
this material is based on work supported by the South Afri-
can National Research Foundation [SA NRF, GUN
2038915 (UFS)]. Opinions, findings, conclusions or recom-
mendations expressed in this material are those of the
authors and do not necessarily reflect the views of the
NRF.
dH(C6D6, 400 MHz): 4.55 (s, 2H, Cp), 4.17 (s, 2H, Cp),
4.10 (s, 2H, Cp), 3.85 (s, 2H, Cp), 3.55 (m, 4H, a-THF),
2.69 (s, 2H, CH2N), 2.02 (s, 6H, 2 CH3), 1.42 (s, 4H, b-
THF), 1.52 (m, 8 H), 1.32 (m, 8H) and 0.88 (m, 16 H)
(SnnBu4).
N,N-dimethylformamide (30 mm3) was condensed into
the NMR tube and the mixture shaken. 1H NMR revealed
quantitative conversion. Water (5 mm3) was added to the
mixture and the yellow mixture turned red immediately.
1
The resulting H NMR revealed quantitative conversion
of the lithium reagent to the carboxaldehyde. dH(C6D6,
400 MHz): 9.8 (s, 1H, CHO), 4.43 (s, 2H, Cp), 4.09 (s,
2H, Cp), 3.99 (s, 2H, Cp), 3.83 (s, 2H, Cp) 3.0 (s, 2H,
CH2N), 2.14 (s, 6H, NMe2). In the mixture, the following
compounds were also present: d: 7.65, 2.38, 1.97 (DMF);
d: 1.55, 1.32, 0.88 (SnnBu4); d: 3.55, 1.41 (THF); d; 1.35
(H2O).
References
[1] P. Beagley, M.A.L. Blackie, K. Chibale, C. Clarkson, R.
Meijboom, J.R. Moss, P.J. Smith, H. Su, Dalton Trans. (2003)
3046.
[2] P. Beagley, M.A.L. Blackie, K. Chibale, C. Clarkson, J.R. Moss,
P.J. Smith, Dalton Trans. (2002) 4426.
The preparative scale synthesis of derivatives of the
dimethylaminomethyl-1-(lithium)-metallocenide reagents
were all performed in a similar method. A representative
example is given.
[3] Ch. Elschenbroich, A. Salzer, Organometallics, A Concise Introduc-
tion, VCH, Weinheim, 1992.
[4] D.W. Slocum, B.W. Rockett, C.R. Hauser, J. Am. Chem. Soc. 87
(1965) 1241.
[5] H. Gornitzka, S. Besser, R. Herbst-Irmer, U. Kiliman, F.T. Edelman,
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Chem. 627 (2001) 2337;
4.4.2. Synthesis of 10-dimethylaminomethylferrocene-1-
carboxaldehyde
A solution of n-BuLi in hexane (0.65 cm3, 1.54 M,
1.0 mmol) was added to a solution of 10-dimethylaminom-
ethyl-1-tri-n-butylstannyl ferrocene (0.532 g, 1.00 mmol) in
THF (5.0 cm3) at ꢀ78 ꢁC in an H-type Schlenk-tube [14].
The mixture was stirred for 30 min at ꢀ78 ꢁC, during
which time a precipitate was seen to form. Several drops
of BuLi in hexane were added to the other leg of the H-type
Schlenk-tube. The volatiles were evaporated in vacuo to
leave a red solid and an oil. Pentane (2.0 cm3) was brought
into the vessel on the BuLi and distilled onto the reaction
mixture (through this extra drying procedure pure solvents
were guaranteed). The mixture was stripped with pentane
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