The synthesis and characterization of 1-formyl-2-acylcyclopentadienylthallium compounds

Article abstract of DOI:10.1016/S0022-328X(01)01185-8

The reaction of sodium cyclopentadienide with RCOOEt (R=Me, Ph, 2-thienyl, or OEt) or Bu^tCOCl followed by Vilsmeier reagent in the presence of excess sodium methoxide produces the 2-substituted-6-dimethylaminofulvenes 1a-e in modest yields. Bas

Full text of DOI:10.1016/S0022-328X(01)01185-8

Journal of Organometallic Chemistry 642 (2002) 268–274
www.elsevier.com/locate/jorganchem
Note
The synthesis and characterization of
1-formyl-2-acylcyclopentadienylthallium compounds
Mark T. Blankenbuehler 1, John P. Selegue *
Department of Chemistry, Uni6ersity of Kentucky, Chemistry–Physics Building, Lexington, KY 40506-0055, USA
Received 12 June 2001; received in revised form 1 August 2001; accepted 12 August 2001
Abstract
The reaction of sodium cyclopentadienide with RCOOEt (R=Me, Ph, 2-thienyl, or OEt) or ButCOCl followed by Vilsmeier
reagent in the presence of excess sodium methoxide produces the 2-substituted-6-dimethylaminofulvenes 1a–e in modest yields.
Basic hydrolysis results in the formation of 2-substituted-6-hydroxyfulvenes 2a–e in very good yields. Subsequent deprotonation
with TlOEt yields the 1-formyl-2-acyl or carboethoxy cyclopentadienylthallium compounds 3a–e. © 2002 Elsevier Science B.V.
All rights reserved.
Keywords: Thallium; Cyclopentadienide; Vilsmeier; Formyl; Acyl; Carboethoxy
1. Introduction
been known for many years [10–19]. Despite their
toxicity, cyclopentadienylthallium reagents offer advan-
tages over their alkali-metal counterparts. They are
generally more stable to air and water, and the ex-
tremely low solubility of thallium(I) halide by-products
drives reactions to completion and facilitates workup.
Our efforts focus on synthesizing precursors to new
metallocene-fused thiophene, pyrrole and furan deriva-
tives [20,21]. In this paper, we report the synthesis of
thallium transfer compounds designed for the prepara-
tion of 1-formyl-2-acylmetallocenes, which can in prin-
ciple be closed to organometallic heterocycles [22,23].
Complexes of specifically polysubstituted cyclopenta-
dienyl ligands play an important role in modern
organometallic chemistry. The development of metal-
locene catalysts for alkene polymerization has driven
efforts to tune catalyst specificity with suitably substi-
tuted cyclopentadienyl ligands [1,2]. In materials appli-
cations, substituted metallocenes can display NLO
properties [3–6], electrical conductivity [7,8] or elec-
trochromism [9]. Unfortunately, electrophilic substitu-
tion reactions carried out on metallocenes have poor
selectivity. Even as simple a reaction as disubstitution
typically leads to a mixture of 1,1%, 1,2 and 1,3 prod-
ucts, with the 1,2-substitution product obtained in the
lowest yield. The method described here leads regiose-
lectively to 1,2-disubstituted cyclopentadienyl ligands
prior to attaching them to a transition metal.
2. Results and discussion
2.1. Synthesis of
1-formyl-2-acylcyclopentadienylthallium compounds
The utility of cyclopentadienylthallium reagents for
the synthesis of new organometallic compounds has
The sequential reaction of sodium cyclopentadienide
with an ester, RCOOEt (R=Me, Ph, Tp; Tp=2-
thienyl) or pivaloyl chloride followed by Vilsmeier
reagent in the presence of excess sodium methoxide
produces the 2-substituted-6-dimethylaminofulvenes
1a–d (Scheme 1). This synthesis essentially follows the
* Corresponding author.
E-mail address: selegue@pop.uky.edu (J.P. Selegue).
1 Present address: Physical Sciences Department, Morehead State
University, Morehead, KY 40351, USA.
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01185-8

M.T. Blankenbuehler, J.P. Selegue / Journal of Organometallic Chemistry 642 (2002) 268–274
269
method of Fujisawa and Sakai [24], who reported a
similar method for the synthesis of 2-acetyl-6-dimethyl-
aminofulvene (1a) and 2-carboethoxy-6-dimethylamino-
fulvene (1e), but did not fully characterize the com-
pounds. Although the tert-butyl compound (1d) was
not formed by using ethyl pivalate, more reactive pival-
oyl chloride gives the desired product in low yield.
Anderson [25] used acetyl chloride and dimethyl sulfate
in DMF to produce 1a in a similar synthesis. Dreiding
[26] prepared 2-isobutyryl-6-dimethylaminofulvene
from dimethylaminofulvene and isobutyryl chloride in
triethylamine, but we were unable to obtain 2-acyl-6-
dimethylaminofulvenes by this method.
The yields of the fulvene compounds 1a–d are rather
low, especially for the sterically demanding tert-butyl
compound 1d. Fortunately the starting materials are
inexpensive, the reactions can be run on fairly large
scales and the yields of subsequent steps (vide infra) are
much higher. We attribute the low isolated yields to
competitive formation of mixtures of 1,2, 1,3 and per-
haps more highly substituted products. Because of their
stability to chromatography on alumina and their crys-
tallinity, the 1,2-disubsitution products can be purified
from the mixtures.
Subsequent hydrolysis of the 1-acyl-2-dimethyl-
aminofulvenes 1a–d with NaOH at 60–80 °C pro-
duced 2-acyl-6-hydroxyfulvenes 2a–d in very good
yields. Finally, deprotonation of 2a–d with thallous
ethoxide yielded the corresponding 1-formyl-2-acylcy-
clopentadienylthallium compounds 3a–d nearly quanti-
tatively (Scheme 1).
The organic [27] and organometallic [28] chemistry of
cyclopentadienes with multiple ester substituents have
been extensively investigated. Previous researchers
found it difficult to obtain 1,2-di(carboalkoxy)cyclo-
pentadiene free of its 1,3-isomer or 1,2,4-triester [29,27].
Although we also find that the ester compounds are
more difficult to purify and handle than the acyl com-
pounds, we obtained 1-formyl-2-carboethoxycyclopen-
tadienylthallium (3e) according to Scheme 1. Unlike the
acyl compounds, 2-carboethoxy-6-dimethylaminoful-
vene (1e) decomposed during purification attempts and
was therefore used in crude form. Subsequent base
hydrolysis of 1e produced carboethoxy compound 2e
that was also difficult to purify and was used in crude
form, so that yields for 1–3e are approximate. Subse-
quent deprotonation of 2e with thallous ethoxide
Scheme 1. Synthesis of compounds 1a–e, 2a–3 and 3a–e.
Table 1
1H-NMR shifts (ppm) for compounds 1, 2 and 3
yielded
1-formyl-2-carboethoxycyclopentadienylthal-
lium (3e), which is surprisingly more sensitive to air
than 3a–d and was therefore handled in a dry box or
with Schlenk techniques. The yields of the ester com-
pounds 1e, 2e and 3e are generally lower than the acyl
compounds.
R
H1
8.97
H2
H3
H4
H5
The thallium compounds consistently analyzed low
in carbon. This is possibly due to the formation of an
inert thallium carbide phase. Compounds 3a–e are
moderately soluble in DMSO but very insoluble in
most other organic solvents and decompose during
attempted sublimation, making purification of analyti-
cal samples difficult.
1a
1b
1c
1d
1e
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
Me
Ph
Tp
7.10
6.98
7.16
7.22
7.14
7.49
7.41
7.73
7.71
7.40
6.49
6.37
6.62
6.54
6.41
6.38
6.44
6.45
6.39
6.39
6.47
6.53
6.55
6.45
6.36
5.70
5.76
5.80
5.68
5.70
6.85
6.83
6.95
6.83
6.80
7.28
7.28
7.36
7.13
6.85
6.49
6.11
6.53
6.42
6.41
–
–
–
–
8.88
8.68
8.80
8.82
8.33
8.75
8.63
8.37
7.70
10.0
10.0
9.95
9.92
9.90
But
OEt
Me
Ph
–
17.10
17.37
17.30
17.67
14.80
–
–
–
–
–
Tp
2.2. Spectroscopic data
But
OEt
Me
Ph
1
Key H-NMR data for compounds 1, 2 and 3 are
listed in Table 1. Each dimethylaminofulvene (1a–e)
displays a characteristic fulvene resonance between 8.6
and 9.0 ppm, in addition to three one-proton multiplets
for the cyclopentadienyl protons and two singlets for
the inequivalent methyl groups. Each 2-acyl-6-hydroxy-
Tp
But
OEt
Compounds 1 and 2 in CDCl3; compounds 3 in DMSO-d6.

270
M.T. Blankenbuehler, J.P. Selegue / Journal of Organometallic Chemistry 642 (2002) 268–274
fulvene (2a–d) shows a characteristic one-proton dou-
blet between 16 and 18 ppm for the acidic hydroxyl
proton. However, the hydroxyl proton resonance of
2-carboethoxy-6-hydroxyfulvene (2e) is shifted about
2–3 ppm upfield of the acyl derivatives. The hydrogen
bonding may be decreased due to the electron-with-
drawing effect of the ethoxy group compared to an
alkyl or aryl group, thus revealing a more typical
hydroxyl proton shift. Compound 2e also displays its
formyl proton (lH=7.70 ppm) considerably upfield of
the acyl compounds (8.3–8.8 ppm). The formyl reso-
nances of the thallium derivatives (3a–e) are shifted to
considerably lower field (9.9–10.0 ppm), and their cy-
clopentadienyl multiplets are shifted by 0.5–1.5 ppm
upfield from 2a–e, consistent with more negative
charge on the cyclopentadienyl ring [30].
4.2. Synthesis of 2-substituted-6-dimethylaminoful6enes
4.2.1. 1,2-C5H3(HCNMe2)(COMe) (1a)
In a dry, N2-purged Schlenk flask cooled to 0 °C in
an ice bath, THF (100 ml), sodium metal (1.44 g, 0.063
mol) and freshly cracked cyclopentadiene (5.0 ml, 0.063
mol) were added and stirred for 4–5 h, when most of
the sodium had been consumed. To the resulting pale
red sodium cyclopentadienide solution was added ethyl
acetate (6.16 ml, 0.063 mol). The mixture was refluxed
for 15–20 h under N2, then cooled to room tempera-
ture (r.t.). Fresh sodium methoxide was prepared by
adding sodium metal (5.0 g, 0.19 mol) to 100 ml of dry
methanol at 0 °C. The solution was stirred and allowed
to warm slowly overnight. The methanol was then
removed in vacuo, leaving white sodium methoxide
powder. The reaction mixture was added to the sodium
methoxide via cannula. Vilsmeier reagent was prepared
by adding freshly distilled POCl3 (5.8 ml, 0.063 mol) at
0 °C to DMF (20 ml) in a Schlenk flask, then stirring
at r.t. for 15–30 min to give a deep orange solution.
The Vilsmeier reagent was added to the deep brown
cyclopentadienide reaction mixture dropwise at 0 °C
over 15 min, followed by stirring for 4 h at r.t. The
reaction mixture was quenched with water and ex-
tracted with ethyl ether. The extracts were dried over
MgSO4, filtered, and the solvent removed in vacuo. The
orange solid 1a (2.3 g, 0.014 mmol) was obtained in
3. Conclusion
The method of Fujisawa is applicable to a variety of
acyl or carboalkoxy groups for the synthesis of 2-sub-
stituted-6-dimethylaminofulvenes and their hydroxyl
derivatives. The 2-acyl and 2-carboethoxy-6-hydroxy-
fulvenes are useful precursors for asymmetric, 1,2-di-
substituted cyclopentadienylthallium compounds. Uti-
lization of these compounds as Cp-transfer reagents
toward a variety of transition metal centers will be
reported in due course.
1
22% yield. H-NMR (200 MHz, CDCl3, ppm) l 8.97 (s,
1H, CHN), 7.10 (dd, 1H, CHCCHN), 6.85 (dd, 1H,
COCCH), 6.38 (dd, 1H, COCCHCH), 3.38 (s, 3H,
NMe), 3.28 (s, 3H, NMe). Lit. [24,25].
4. Experimental
4.1. General methods and sources
4.2.2. 1,2-C5H3(HCNMe2)(COPh) (1b)
As described for 1a, sodium cyclopentadienide was
prepared from sodium (1.44 g, 0.063 mol) and cy-
clopentadiene (5.0 ml, 0.063 mol) in THF (100 ml). To
the resulting pale red solution was added ethyl benzoate
(9.0 ml, 0.063 mol). The mixture was refluxed for 15–20
h under N2 then cooled to r.t. The reaction mixture was
added via cannula to sodium methoxide, prepared from
sodium (5.0 g, 0.19 mol) in 100 ml of dry methanol.
Vilsmeier reagent, prepared from POCl3 (5.8 ml, 0.063
mol) and DMF (20 ml), was added to the deep brown
reaction mixture dropwise at 0 °C over 15 min, fol-
lowed by stirring for 4 h at r.t. The reaction mixture
was quenched and worked up as described for 1a,
followed by column chromatography with ethyl ether
eluent on alumina (Act. III) to give the orange solid 1b
Reactions were carried out using standard Schlenk
techniques under a nitrogen atmosphere or in a Braun
MB 120-G dry box unless otherwise noted. Solvents
were dried and distilled under nitrogen, including
methanol over calcium hydride, DMF over calcium or
magnesium sulfate and THF over sodium benzophe-
none ketyl. CDCl3 and Me2SO-d6 were used as received
from Cambridge Isotopes. Phosphorus oxytrichloride
(Baker), ethyl acetate (Fisher), ethyl pivalate (Aldrich),
ethyl benzoate (Baker), pivaloyl chloride (Aldrich) and
diethyl carbonate (Aldrich) were distilled under nitro-
gen before use. Ethyl-2-thiophene carboxylate and thal-
lous ethoxide were used as received from Aldrich.
Proton and carbon NMR spectra were obtained on
Varian Gemini 200 or Varian VXR-400 NMR spec-
trometers. Infrared spectra were obtained on a Mattson
Galaxy Series FTIR 5000. Melting points are uncor-
rected. Elemental analyses were performed at the Uni-
versity of Illinois, Urbana. Mass spectra were collected
at the University of Kentucky Mass Spectrometry
Center.
1
(2.2 g, 0.010 mol) in 16% yield. H-NMR (200 MHz,
CDCl3, ppm) l 8.88 (s, 1H, CHNMe2), 7.76 (m, 2H,
3
Ph), 7.43 (m, 3H, Ph), 6.98 (dd, 1H, CNCCH, JHH
=
4.4 Hz, 4JHH=1.6 Hz), 6.83 (dd, 1H, CHOCCH,
3JHH=3.6 Hz, 4JHH=1.6 Hz), 6.44 (dd, 1H,
CHCHCH, 3JHH=3.6, 3.6 Hz), 3.40 (s, 3H, NMe),
3.33 (s, 3H, NMe); 13C{1H}-NMR (50 MHz, CDCl3,

M.T. Blankenbuehler, J.P. Selegue / Journal of Organometallic Chemistry 642 (2002) 268–274
271
ppm) l 154.8 (CHO), 141.9 (CN), 133.9 (p-Ph), 130.4
(Cp), 129.8 (CHOCCH), 129.2 (o-Ph), 128.3
(CNCCH), 127.7 (m-Ph), 123.8 (Cp), 121.2 (Cp), 115.2
(i-Ph), 48.0 (NMe), 40.8 (NMe); IR (neat, cm−1) 1621
(CO); m.p.=113–114 °C; MS (EI) [M+] for
mixture was quenched and worked up as described for
1b, except that chromatography was carried out with
hexane eluent to give the bright yellow solid 1d (0.65 g,
3.1 mmol) in 5% yield. H-NMR (200 MHz, CDCl3,
ppm) l 8.8 (s, 1H, CHNMe2), 7.22 (m, 1H, Cp), 6.83
1
12
1
C H14N16O, m/z 225, isotope pattern matches calcu-
(m, 1H, Cp), 6.39 (m, 1H, Cp), 3.36 (s, 3H, NMe), 3.29
15 15
t
lated pattern. Anal. Calc. for C15H15NO: C, 79.97; H,
6.71; N, 6.22. Found: C, 80.28; H, 6.63; N, 5.09%.
(s, 3H, NMe), 1.38 (s, 9H, Bu); 13C{1H}-NMR (50
MHz, CDCl3, ppm)
l
204.4 (COtBu), 155.2
(CHNMe2), 128.7 (Cp), 127.1 (q-Cp), 121.5 (Cp), 120.2
(Cp), 115.7 (q-Cp), 48.0 (NMe), 44.3 (C(CH3)), 40.9
(NMe), 29.4 (C(CH3)); IR (neat, cm−1) 1620 (CO);
4.2.3. 1,2-C5H3(HCNMe2)(COTp) (1c; Tp=2-thienyl)
As described for 1a, sodium cyclopentadienide was
prepared from sodium (0.73 g, 0.032 mol) and cy-
clopentadiene (2.5 ml, 0.032 mol) in THF (100 ml). To
the resulting pale red solution was added 2-thiophene
carboxylate (4.3 ml, 0.032 mol). The mixture was
refluxed for 15–20 h under N2 then cooled to r.t. The
reaction mixture was added via cannula to sodium
methoxide, prepared from sodium (2.5 g, 0.095 mol) in
50 ml of dry methanol. Vilsmeier reagent, prepared
from POCl3 (2.9 ml, 0.032 mol) and DMF (10 ml), was
added to the deep brown reaction mixture dropwise at
0 °C over 15 min, followed by stirring for 4 h at r.t.
The reaction mixture was quenched, worked up and
chromatographed as described for 1b to give the orange
m.p.=43–44 °C; MS (EI) [M+] for 12C113H N16O, m/z
14
19
205, isotope pattern matches calculated pattern. Anal.
Calc. for C13H19NO: C, 76.05; H, 9.33; N, 6.82. Found:
C, 75.54; H, 9.08; N, 6.42%.
4.2.5. 1,2-C5H3(HCNMe2)(COOEt) (1e)
As described for 1a, sodium cyclopentadienide was
prepared from sodium (1.44 g, 0.063 mol) and cy-
clopentadiene (5.0 ml, 0.063 mol) in THF (100 ml). To
the resulting pale red solution was added diethyl car-
bonate (7.4 ml, 0.063 mol). The mixture was refluxed
for 15–20 h under N2 then cooled to r.t. The reaction
mixture was added via cannula to sodium methoxide,
prepared from sodium (5.0 g, 0.19 mol) in 100 ml of dry
methanol. Vilsmeier reagent, prepared from POCl3 (5.8
ml, 0.063 mol) and DMF (20 ml), was added to the
deep brown reaction mixture dropwise at 0 °C over 15
min, followed by stirring for 4 h at r.t. The reaction
mixture was quenched and worked up as described for
1a to give the orange solid 1e (0.55 g, 2.8 mmol) in 5%
1
solid 1c (1.1 g, 4.7 mmol) in 15% yield. H-NMR (200
MHz, CDCl3, ppm) l 8.68 (s, 1H, CHN), 7.70 (dd, 1H,
3
4
COCCHCHCHS, JHH=3.6 Hz, JHH=1.1 Hz), 7.53
3
4
(dd, 1H, COCCHCHCHS, JHH=5.1 Hz, JHH=1.1
3
Hz), 7.16 (dd, 1H, CHNCCHCHCH, JHH=3.7 Hz,
4JHH=1.7 Hz), 7.09 (dd, 1H, COCCHCHCHS,
3JHH=5.1 Hz, JHH=3.6 Hz), 6.95 (dd, 1H, CHNC-
3
1
CHCHCH, 3JHH=3.7 Hz, 4JHH=1.7 Hz), 6.45 (dd,
yield. H-NMR (200 MHz, CDCl3, ppm) l 8.82 (s, 1H,
3
4
1H, CHNCCHCHCH, JHH=3.7 Hz, JHH=3.7 Hz),
3.35 (s, 3H, NMe), 3.29 (s, 3H, NMe); 13C{1H}-NMR
(50 MHz, CDCl3, ppm) l 183.1 (COTp), 154.2 (CHN),
146.8 (COCCH), 131.6, 131.1, 130.9, 129.9 (SCCO),
127.1, 123.4, 121.1, 114.9 (TpCOC), 48.0 (NCH3), 40.8
(NCH3); IR (Neat, cm−1) 1619 (CO); m.p.=105–
CHN), 7.14 (m, 1H, CHCCHN), 6.80 (m, 1H,
COCCH), 6.39 (m, 1H, COCCHCH), 4.22 (q, 2H, Et),
3.35 (bs, 6H, NMe), 1.32 (t, 3H, Et); lit. [24] (synthesis
but no spectroscopic data).
4.3. Synthesis of 2-substituted-6-hydroxyful6enes
12
106 °C; MS (EI) [M+] for C113H1143N16O32S, m/z 231,
isotope pattern matches calculated pattern. Anal. Calc.
for C13H13NOS: C, 67.50; H, 5.66; N, 6.05. Found: C,
67.40; H, 5.65; N, 5.72%.
4.3.1. 1,2-C5H3(CHOH)(COMe) (2a)
Excess aq. NaOH (100 ml, 2 M) was added to
1,2-C5H3(HCNMe2)(COMe) (1a, 2.3 g, 0.014 mol) in a
round-bottom flask, and the mixture was heated to
60–80 °C for 4 h with a slow nitrogen purge. A yellow
precipitate formed when the reaction was acidified with
concentrated sulfuric acid. The mixture was extracted
with ethyl ether and the extract was rinsed with water.
The organic layer was dried over MgSO4, filtered and
the solvent removed in vacuo to yield the yellow–or-
ange oil 2a (1.9 g, 0.014 mol) in quantitative yield.
1H-NMR (200 MHz, CDCl3, ppm) l 17.1 (d, 1H,
4.2.4. 1,2-C5H3(HCNMe2)(COBut) (1d)
As described for 1a, sodium cyclopentadienide was
prepared from sodium (1.44 g, 0.063 mol) and cy-
clopentadiene (5.0 ml, 0.063 mol) in THF (100 ml). To
the resulting pale red solution was added pivaloyl chlo-
ride (7.7 ml, 0.063 mol). The mixture was refluxed for
15–20 h under N2 then cooled to r.t. The reaction
mixture was added via cannula to sodium methoxide,
prepared from sodium (5.0 g, 0.19 mol) in 100 ml of dry
methanol. Vilsmeier reagent, prepared from POCl3 (5.8
ml, 0.063 mol) and DMF (20 ml), was added to the
deep brown reaction mixture dropwise at 0 °C over 15
min, followed by stirring for 4 h at r.t. The reaction
3
3
CHOH, JHH=7.6 Hz), 8.33 (dd, 1H, CHO, JHH=7.8
4
Hz, JHH=1.0 Hz), 7.49 (m, 1H, CHOCH), 7.28 (dd,
3
3
1H, CHCCOCH3, JHH=3.7 Hz, JHH=1.8 Hz), 6.47
3
(dd, 1H, CHCHCH, JHH=3.7, 3.7 Hz), 2.53 (s, 3H,
COCH3); 13C{1H}-NMR (50 MHz, CDCl3, ppm) l

272
M.T. Blankenbuehler, J.P. Selegue / Journal of Organometallic Chemistry 642 (2002) 268–274
188.5 (COCH3), 175.6 (COH), 139.5 (Cp), 138.6 (Cp),
125.8 (CHCCHO), 124.8 (CHCCOCH3), 123.3
(CHCHCH), 23.1(CH3); lit. [24] 1H-NMR 17.1 (s,
CHOH).
4.3.4. 1,2-C5H3(CHOH)(COtBu) (2d)
1,2-C5H3(HCNMe2)(COBut) (1d, 0.650 g, 3.17 mmol)
was treated with aq. NaOH (100 ml, 2 M) as described
for 2a. A workup identical to 2a gave the yellow–or-
ange oil 2d (0.536 g, 3.01 mmol) in 95% yield. 1H-NMR
(200 MHz, CDCl3, ppm) l 17.67 (d, 1H, CHOH,
4.3.2. 1,2-C5H3(CHOH)(COPh) (2b)
3JHH=8.8 Hz), 8.37 (dd, 1H, CHOH, JHH=8.8 Hz,
3
4.3.2.1. Method A. 1,2-C5H3(HCNMe2)(COPh) (1b, 2.2
g, 0.01 mol) was treated with aq. NaOH (100 ml, 2 M)
as described for 2a with a reaction time of 6 h. An
identical workup to 2a gave the yellow–orange oil 2b
(1.98 g, 0.01 mol) in quantitative yield.
4JHH=1.6 Hz), 7.71 (m, 1H, Cp), 7.13 (dd, 1H, Cp,
3JHH=4.0 Hz, 4JHH=1.6 Hz), 6.45 (dd, 1H, Cp,
t
3JHH=4.0, 4.0 Hz), 1.45 (s, 9H, Bu); 13C{1H}-NMR
(50 MHz, CDCl3, ppm) l 200.6 (COtBu), 173.0 (CHO),
138.8 (Cp), 137.7 (Cp), 125.8 (q-Cp), 122.9 (q-Cp),
122.6 (Cp), 42.5 (C(CH3)3), 29.9 (C(CH3)3); IR (neat,
4.3.2.2. Method B. [Tl{C5H3(CHOH)(COPh)}] (3b, 0.20
g, 0.50 mmol) was placed in a round-bottom flask with
ethyl ether (15 ml) and water (15 ml). Concentrated
hydrochloric acid (2–4 drops) was added and the reac-
tion was stirred for 5 h at r.t. The reaction was ex-
tracted with ethyl ether and water. The yellow organic
layer was filtered, dried with MgSO4, filtered and the
solvent removed in vacuo to give the yellow oil 2b
(0.095 g, 0.48 mmol) in quantitative yield. 1H-NMR
(200 MHz, CDCl3, ppm) l 17.37 (d, 1H, CHOH,
cm−1) 1628 (br, CO); MS (EI) [M+] for C111H1146O2,
12
m/z 178, isotope pattern matches calculated pattern.
Anal. Calc. for C11H14O2: C, 74.13; H, 7.92. Found: C,
74.94; H, 6.63%.
4.3.5. 1,2-C5H3(CHOH)(COOEt) (2e)
Crude 1,2-C5H3(HCNMe2)(COOEt) (1e) was treated
with aq. NaOH (100 ml, 2 M) as described for 2a. A
workup identical to 2a gave the yellow–orange oil 2e in
3JHH=7.0 Hz), 8.75 (dd, 1H, CHO, 3JHH=7.0, 4JHH
1.2 Hz), 7.87 (m, 2H, Ph), 7.55 (m, 3H, Ph), 7.41 (dd,
=
1
over 90% yield. H-NMR (200 MHz, CDCl3, ppm) l
3
3
14.8 (d, 1H, JHH=14.8 Hz), 7.7 (d, 1H, JHH=14.8
Hz), 7.4 (m, 1H), 6.85 (m, 1H), 6.36 (m, 1H), 4.35 (q,
2H, CH2), 1.37 (t, 3H, CH3); 13C{1H}-NMR (50 MHz,
CDCl3, ppm) l 163.0 (CO), 138.7 (COCCHCHCH),
133.4 (COCCHCHCH), 123.3 (CHCHCH), 61.7
(CH2), 14.2 (CH3); lit. [24] (synthesis but no spectro-
scopic data).
3
4
1H, Cp, JHH=3.9 Hz, JHH=1.8 Hz), 7.28 (m, 1H,
Cp), 6.53 (dd, 1H, Cp, JHH=3.9, 3.9 Hz); 13C{1H}-
3
NMR (50 MHz, CDCl3, ppm) l 184.3 (CO), 176.9
(CHOH), 141.7 (Cp), 141.1 (Cp), 136.9 (i-Ph), 131.6
(Ph), 130.2 (q-Cp), 129.6 (Ph), 128.3 (Ph), 127.2 (q-Cp),
124.2 (Cp); IR (neat, cm−1) 1598 (br, CO); MS (EI)
12
[M+] for C113H1106O2, m/z 198, isotope pattern matches
calculated pattern. Anal. Calc. for C13H10O2: C, 78.77;
H, 5.08. Found: C, 71.80; H, 4.69%.
4.4. Synthesis of 1,2-substituted
cyclopentadienylthallium compounds
4.3.3. 1,2-C5H3(CHOH)(COTp) (2c)
1,2-C5H3(HCNMe2)(COTp) (1c, 1.1 g, 4.7 mmol) was
treated with aq. NaOH (100 ml, 2 M) as described for
2a with a reaction time of 6 h. A workup identical to 2a
gave the yellow–orange oil 2c (0.95 g, 4.7 mmol) in
4.4.1. [Tl{1,2-C5H3(CHO)(COMe}] (3a)
Thallous ethoxide (3.0 g, 0.012 mol) was added via
syringe to a solution of 1,2-C5H3(CHOH)(COMe) (2a,
1.66 g, 0.012 mol) in THF (50 ml). A precipitate formed
quickly and the reaction mixture was stirred at r.t.
overnight. The THF was removed in vacuo and ethyl
ether (ca. 50 ml) was added. The tan, solid product 3a
(4.0 g, 0.012 mol) was filtered out of the suspension in
1
quantitative yield. H-NMR (200 MHz, CDCl3, ppm) l
17.3 (d, 1H, CHOH, 3JHH=8.0 Hz), 8.63 (dd, 1H,
CHO, 3JHH=8.0 Hz, 4JHH=1.2 Hz), 7.87 (dd, 1H,
3
4
COCCHCHCHS, JHH=3.6 Hz, JHH=1.2 Hz), 7.73
(m, 1H, CHOHCCHCHCH), 7.68 (dd, 1H, COC-
3
4
1
CHCHCHS, JHH=5.2 Hz, JHH=1.2 Hz), 7.36 (dd,
1H, CHOHCCHCHCH, 3JHH=3.6 Hz, 4JHH=1.2
Hz), 7.18 (dd, 1H, COCCHCHCHS, 3JHH=5.2 Hz,
3JHH=3.7 Hz), 6.55 (dd, 1H, CHOHCCHCHCH,
3JHH=3.6, 3.6 Hz); 13C{1H}-NMR (50 MHz, CDCl3,
ppm) l 175.8 (CO), 175.6 (CHOH), 140.5 (Tp), 139.6
(Tp), 133.5 (Tp), 132.7 (Cp), 128 (COCCHCHCHS),
127.9 (Cp), 126.7 (CHOHCCH), 124.2 (Cp), 123.3
(COCCH); IR (neat, cm−1) 1623 (br, CO); MS (EI)
quantitative yield. H-NMR (200 MHz, Me2SO, ppm)
l 10.0 (s, 1H, CHO), 6.49 (m, 2H, CHCHCH), 5.7 (dd,
1H, CHCHCH, 3JHH=3.4, 3.4 Hz), 2.21 (s, 3H,
COCH3); 13C{1H}-NMR (50 MHz, Me2SO, ppm) l
191.3 (CHO), 185.6 (COCH3), 126.5 (CHCCOMe),
126.4 (CHOCCH), 122.4 (CHOCCH), 117.3
(CHCHCH), 112.4 (COCH3CCH), 27.5 (COCH3); IR
(Nujol, cm−1) 1622, 1585 (CO); m.p. \170 °C (dec.);
MS (EI) [M+] for 12C18H176O2204Tl, m/z 340 [MH+],
isotope pattern matches calculated pattern. Anal. Calc.
for C8H7O2Tl: C, 28.30; H, 2.07. Found: C, 28.91; H,
2.05%.
12
1
[M+] for
C H186O322S, m/z 204, isotope pattern
11
matches calculated pattern. Anal. Calc. for C11H8O2S:
C, 64.69; H, 3.95. Found: C, 65.40; H, 3.85%.

M.T. Blankenbuehler, J.P. Selegue / Journal of Organometallic Chemistry 642 (2002) 268–274
273
4.4.2. [Tl{1,2-C5H3(CHO)(COPh)}] (3b)
4.4.5. [Tl{1,2-C5H3(CHO)(COOEt)}] (3e)
As described for 3a, thallous ethoxide (0.75 g, 3.0
mmol) reacted with 1,2-C5H3(CHOH)(COPh) (2b, 0.54
g, 2.7 mmol) in THF (50 ml). The same workup gave
the tan solid 3b (1.0 g, 2.6 mmol) in over 95% yield.
1H-NMR (200 MHz, Me2SO, ppm) l 10.0 (s, 1H,
CHO), 7.57 (m, 2H, Ph), 7.37 (m, 3H, Ph), 6.37 (dd,
As described for 3a, thallous ethoxide (0.75 g, 3.0
mmol) reacted with 1,2-C5H3(CHOH)(COOEt) (2e,
0.50 g, 3.0 mmol) in THF (50 ml). The same workup
gave the air-sensitive, brown solid 3e (0.85 g, 2.3 mmol)
1
in 76% yield. H-NMR (200 MHz, Me2SO, ppm) l 9.9
(d, 1H, CHO, 4JHH=1.0 Hz), 6.41 (overlapping dd,
3
4
3
1H, Cp, JHH=3.6 Hz, JHH=1.8 Hz), 6.11 (dd, 1H,
2H, CHCHCH), 5.7 (ddd, 1H, CHCHCH, JHH=3.8,
3
4
5
Cp, JHH=3.6 Hz, JHH=1.8 Hz), 5.76 (dd, 1H, Cp,
3JHH=3.6, 3.6 Hz); 13C{1H}-NMR (50 MHz, Me2SO,
ppm) l 189 (COPh), 185.4 (CHO), 143.6 (i-Ph), 129.0
(Ph), 128.6 (q-Cp), 128.5 (Ph), 127.5 (q-Cp), 127.3 (Ph),
3.8 Hz, JHH=1.0 Hz), 4.04 (q, 2H, CH2), 1.2 (t, 3H,
CH3); 13C{1H}-NMR (50 MHz, Me2SO, ppm) l 183.9
(CHO), 165.5 (COO), 126.1 (CHOC), 120.0 (COOC-
CH), 115.2 (CHOCCHCHCH), 114.8 (COOCCH),
112.0 (CHOCCHCH), 57.2 (CH2), 14.8 (CH3); IR
(Nujol, cm−1) 1646 (m), 1570 (b, s), 1460 (b, s);
m.p. \100 °C (dec.); MS (EI) [M+] for 12C91H916O3204Tl,
370 [MH+], isotope pattern matches calculated pattern.
Anal. Calc. for C9H9O3Tl: C, 29.25; H, 2.45. Found:
C, 24.20; H, 2.01%.
125.3 (Cp), 117.8 (Cp), 112.9 (Cp); IR (Nujol, cm−1
)
1585 (CO); m.p. \180 °C (dec.); MS (EI) [M+] for
13
12
1
C H196O2204Tl, observed decomposition products only.
Anal. Calc. C13H9O2Tl: C, 38.88; H, 2.26. Found: C,
37.28; H, 2.32%.
4.4.3. [Tl{1,2-C5H3(CHO)(COTp)}] (3c)
Acknowledgements
As described for 3a, thallous ethoxide (0.93 g, 3.7
mmol) reacted with 1,2-C5H3(CHOH)(COTp) (2c, 0.76
g, 3.7 mmol), in THF (50 ml). The same workup gave
We thank the National Science Foundation (EP-
SCoR EPS-9452895 and MRSEC DMR-9809686) and
the US Department of Energy (DE-FG02-00ER45847
and subcontract 10186-00-23) for support of this
research.
1
the tan solid 3c (1.3 g, 3.3 mmol) in 89% yield. H-
NMR (200 MHz, Me2SO, ppm) l 9.95 (s, 1H, CHO),
7.67 (d, 1H, Tp, 3JHH=5.1 Hz), 7.55 (d, 1H, Tp,
3
3JHH=3.3 Hz), 7.1 (dd, 1H, Tp, JHH=4.0, 4.0 Hz),
6.62 (m, 1H, Cp), 6.53 (m, 1H, Cp), 5.8 (dd, 1H, Cp,
3JHH=3.3, 3.3 Hz); 13C{1H}-NMR (50 MHz, Me2SO,
ppm) l 185.27 (CHO), 179.81 (COTp), 148.6 (q-Tp),
129.75 (Tp), 129.59 (Tp), 127.60 (q-Cp), 127.21 (Tp),
125.25 (q-Cp), 123.27 (Cp), 117.89 (Cp), 113.20 (Cp);
IR (Nujol, cm−1) 1571 (CO); m.p. \150 °C (dec.);
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12
for C111H1136O2204Tl, m/z 382, isotope pattern matches
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34.62; H, 3.43. Found: C, 29.36; H, 2.76%.

274
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