Practical Chromatography-Free Synthesis of 2-Iodo- N, N -diiso propylferrocenecarboxamide and Further Transformations

Article abstract of DOI:10.1055/s-0039-1689917

An efficient procedure able to deliver grams of racemic and enantioenriched 2-iodo- N, N -diisopropylferrocenecarboxamide without chromatographic purification was developed. To introduce the halogen, two procedures, one using the n BuLi-TMEDA chelate and one using a lithium amide in the presence of ZnCl ₂ as in situ trap were developed. Further functionalization by Suzuki-Miyaura and Ullman-type cross-couplings was investigated to access a variety of ferrocene derivatives.

Full text of DOI:10.1055/s-0039-1689917

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2019, 51, A–I
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W. Erb et al.
PSP
Synthesis
Practical Chromatography-Free Synthesis of 2-Iodo-N,N-diiso-
propylferrocenecarboxamide and Further Transformations
William Erb*
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Thierry Roisnel
Vincent Dorcet
Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de
Rennes) – UMR 6226, 35000 Rennes, France
william.erb@univ-rennes1.fr
Received: 13.04.2019
Accepted after revision: 16.05.2019
Published online: 12.06.2019
(+)-sparteine surrogate was required to deliver the opposite
enantiomer of 2-substituted ferrocenecarboxamide with a
high level of stereocontrol.9 It should be pointed out that,
though 1 has mainly been functionalized by deprotolithia-
tion, its deproto-mercuration,10 -cupration,11 and -zinca-
tion12 have also be reported to prepare compounds that are
otherwise hardly accessible.
In the frame of our ongoing research program dedicated
to the synthesis of original ferrocene derivatives,13 we re-
quired large quantities of 2-iodo-N,N-diisopropylferrocene-
carboxamide (2) in both racemic and enantioenriched
forms. Although already reported in the literature, the pro-
tocols relying on chromatographic purification were not
compatible with the scale required here.
DOI: 10.1055/s-0039-1689917; Art ID: ss-2019-z0222-psp
Abstract An efficient procedure able to deliver grams of racemic and
enantioenriched 2-iodo-N,N-diisopropylferrocenecarboxamide without
chromatographic purification was developed. To introduce the halogen,
two procedures, one using the nBuLi-TMEDA chelate and one using a
lithium amide in the presence of ZnCl2 as in situ trap were developed.
Further functionalization by Suzuki–Miyaura and Ullman-type cross-
couplings was investigated to access a variety of ferrocene derivatives.
Key words ferrocene, carboxamide, large-scale synthesis, deproto-
metalation, Suzuki–Miyaura cross-coupling, Ullmann-type cross-cou-
pling
Discovered in 1951, ferrocene is currently one of the
most important organometallic scaffolds with multiple ap-
plications in redox sensing, catalysis, materials science, and
medicinal chemistry.1 Due to its planar chirality when two
different substituents are located on the same ring of a fer-
rocene, the search for asymmetric syntheses has been a re-
curring question in metallocene science.2 The diastereose-
lective ortho-deprotometalation (DoM) is a powerful meth-
odology but implies multiple steps to install and remove,
when possible, the chiral directing group. Therefore, only a
few directing groups are usually used in this strategy.3 En-
zymatic and chemical kinetic resolution have been investi-
gated with various levels of success but are not general.4 Re-
cent years have witnessed the emergence of catalytic asym-
metric ferrocene C–H bond activation.5 However, due to the
use of an expensive catalytic system and, although growing,
still limited functionalization scope, this approach remains
limited. The enantioselective DoM of monosubstituted fer-
rocenes is another approach, which relies on the ability of a
chiral base to discriminate between both enantiotopic pro-
tons. Although various substrates have been evaluated over
the years,6 N,N-diisopropylferrocenecarboxamide (1) af-
forded the best results when treated with the nBuLi-(–)-
sparteine chelate before interception with an electrophile.7
Even if the availability and prices of sparteine enantiomers
have varied over time, (+)-sparteine has remained the most
expensive for a long period.8 Therefore, the use of O’Brien’s
Here we describe the chromatography-free large scale
synthesis of (±)-2 and the gram-scale synthesis of (Sp)-2
(Scheme 1). The usefulness of 2 in organic synthesis was
further demonstrated by its functionalization through pal-
ladium-catalyzed Suzuki–Miyaura and copper-mediated
Ullmann-type cross-couplings.
I
1) tBuLi, tBuOK
2) CO2
1) base
2) I2
CONiPr2
CONiPr2
Fe
Fe
Fe
3) (COCl)2
4) iPr2NH
1
2
[36 g prepared]
O
R
O
Ar
ArB(OH)2, [Pd]
CONiPr2
or
Fe
CONiPr2
or
Fe
RCO2H, [Cu]
[7 examples]
[9 examples]
Scheme 1 Gram-scale synthesis of (±)-2 and (Sp)-2 and their further
functionalization
Commercially available ferrocenecarboxylic acid (3) re-
maining expensive, our synthesis starts from ferrocene,
which is metalated using an excess of tBuLi in the presence
of a catalytic amount of tBuOK, as described by Mueller-
Westerhoff (Scheme 2).14 Upon metalation completion, gas-
eous carbon dioxide is passed through the reaction mixture
to afford, after acidic workup, ferrocenecarboxylic acid (3)
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
W. Erb et al.
PSP
Synthesis
in 94% yield (34 g in a single batch). It was subsequently
converted into N,N-diisopropylferrocenecarboxamide (1)
by a two-step process: formation of the acyl chloride by
treatment with an excess of oxalyl chloride in the presence
of catalytic amounts of dimethylformamide and reaction
with diisopropylamine. In our optimized protocol, which
does not require anhydrous conditions, the crude product
can be obtained in a couple of hours. Usually purified by
column chromatography, we found that a simple recrystal-
lization of the crude reaction mixture from heptane affords
analytically pure product in 96% yield. Racemic deprotome-
talation of compound 1 can be performed using nBuLi in
the presence of N,N,N′,N′-tetramethylethylenediamine
(TMEDA) to enhance its reactivity in diethyl ether. We brief-
ly studied the possibility to carry out this transformation
with the more reactive sBuLi in THF at –78 °C; however,
moderate yields (68% on average), resulting from the for-
mation of multiple by-products, were obtained. Therefore,
the deprotometalation with the nBuLi-TMEDA chelate in di-
ethyl ether at cryogenic temperature was performed, fol-
lowed by iodine interception. After a traditional workup
and removal of insoluble by-products, a simple recrystalli-
zation allowed the isolation of 36 g of the title product (±)-2
in a single batch (88% yield).
asymmetric deprotometalation of 1 at a scale similar to that
of the racemic one was economically not viable. By follow-
ing O’Brien’s protocol,9 we therefore prepared 1.4 grams of
(Sp)-2 (69% yield) with an enantiomeric ratio (er) of 96:4 as
determined by chiral HPLC (Scheme 3). Interestingly, a sim-
ple recrystallization increases the er up to 99:1. Initially in-
ferred by optical rotation measurement, the absolute con-
figuration of (Sp)-2 was confirmed by X-ray diffraction anal-
ysis (see SI).
1) nBuLi
(+)-sparteine surrogate
(+)-sparteine surrogate
H
Et2O, toluene, –78 °C
N
CONiPr2
CONiPr2
I
Fe
Fe
2) I2
N
Et2O, –78 °C to rt
1
(Sp)-2 69%
96:4 er
[1.4 g prepared]
Scheme 3 Enantioselective synthesis of compound (Sp)-2
Therefore, assuming that (–)-sparteine or (+)-sparteine
surrogate are accessible in sufficient quantities, ten or so
grams of the enantioenriched ferrocene 2 can be prepared
in a few days without recurring to chromatographic purifi-
cation. This is especially relevant with the (+)-sparteine sur-
rogate, which can be used in catalytic amount without ma-
jor drop in the er.
Although we previously demonstrated the usefulness of
2 to access original 3-iodo-N,N-diisopropylferrocenecar-
boxamide through a halogen ‘dance’ reaction,13,17 the func-
tionalization of the former was not extensively studied. In
2014, Kumar has reported an original example of a tBuOK-
mediated sp3 C–H bond functionalization to access lactams
in 96% yield from (±)-2.18 Earlier, Snieckus showed that the
Suzuki–Miyaura cross-coupling of (Rp)-2 under aqueous
conditions afforded the desired biaryl product in low yield
but with unchanged enantiomeric ratio (31% yield, 98:2
er).7 More recently, Anderson showed the ability of Cu2O to
perform an Ullmann-type cross-coupling between (Rp)-2
and either phthalimide or acetic acid.19 The positive optical
rotation recorded clearly indicated that enantioenriched
products were obtained but without further indication of
the enantiomeric ratio.
1) (COCl)2
CH2Cl2, rt
1) tBuLi, tBuOK
THF, –78 °C
CO2H
CONiPr2
Fe
Fe
Fe
2) CO2
3) H3O+
2) iPr2NH
CH2Cl2, rt
[34 g prepared]
3 94%
[36 g prepared] 1 96%
1) nBuLi/TMEDA, Et2O, –78 °C
2) I2, Et2O, –78 °C to rt
I
88% [36 g prepared]
CONiPr2
CONiPr2
)-2
Fe
Fe
1) ZnCl2, THF, –30 °C
2) LiTMP
1
(
3) I2, THF, –30 °C to rt
93% [20 g prepared]
Scheme 2 Column chromatography-free multi-gram synthesis of (±)-2
For practical reasons, we have also developed another
large scale synthesis of (±)-2 by following the in situ trap-
ping strategy.15 Thus, 1 was reacted with LiTMP (TMP =
2,2,6,6-tetramethylpiperidide) in the presence of anhy-
drous ZnCl2 as the in situ trap in THF before interception
with iodine. By following a similar workup and crystalliza-
tion purification protocol, 20 g of (±)-2 was isolated in a
single batch (93% yield).
Having established a reliable multi-gram access toward
(±)-2, we turned our attention to its enantioenriched form.
As the use of O’Brien’s (+)-sparteine surrogate has not yet
been attempted on 1, we thought it interesting to secure
this way. However, and even though (+)-sparteine surrogate
is easily available from natural sources,16 performing the
Therefore, we thought it interesting to apply Suzuki–
Miyaura reaction conditions able to deliver the desired
products in higher yields. The full transfer of chiral infor-
mation being already reported, we focused our study on ra-
cemic compounds. As aqueous reaction conditions seem to
promote dehalogenation instead of the desired coupling re-
action on such substrates, we successfully switched to an-
hydrous conditions. Therefore, reacting (±)-2 with phenyl-
boronic acid in the presence of Pd(dba)2 (dba = dibenzylide-
neacetone), PPh3, and CsF in toluene smoothly afforded the
title product (±)-4 in 59% yield (Scheme 4). Following the
general reactivity trend of boronic acids in the Suzuki–Mi-
yaura cross-coupling,20 the electron-rich ones afforded
higher yields [compounds (±)-5–7], while a major yield
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I

C
W. Erb et al.
PSP
Synthesis
drop was noticed with the chlorinated and trifluoromethyl-
ated ones [compounds (±)-8–10]. In these cases, moderate
conversions as well as competitive dehalogenation were no-
ticed. The use of ferroceneboronic acid,21 2-thienylboronic
acid, or 4-nitrophenylboronic acid only led to recovery of
starting material or degradation.
material. Finally, acrylic acid derivatives such as 3,4-methy-
lenedioxycinnamic acid and piperic acid were successfully
converted into the corresponding esters (±)-18 and (±)-19
(88% and 92% yield, respectively).
O
R
I
O
CONiPr2
carboxylic acid, Cu2O
MeCN, 90 °C
boronic acid
cat. Pd(dba)2
PPh3, CsF
I
Ar
CONiPr2
Fe
CONiPr2
Fe
CONiPr2
Fe
Fe
toluene, 120 °C
O
O
O
O
F
OMe
MeO
O
OMe
CONiPr2
O
CONiPr2
CONiPr2
CONiPr2
CONiPr2
CONiPr2
CONiPr2
Fe
Fe
Fe
Fe
Fe
Fe
Fe
(
)-11: 85%
(
)-12: quant
(
)-13: 87%
(Sp)-11: 76%, 89:11 er
(
)-4 59%
(
)-5 77%
(
)-6 64%
(
)-7 65%
Cl
CF3
Cl
AcO
O
O
Fe
CONiPr2
CONiPr2
O
CONiPr2
Fe
Fe
(
Fe
O
CONiPr2
Fe
CONiPr2
O
O
Fe
(
)-8 11%
(
)-9 29%
)-10 21%
(
)-16: 85%
(
)-14: 72%
Scheme 4 Suzuki–Miyaura cross-coupling between (±)-2 and various
O
O
boronic acids
iPr2NOC
CONiPr2
Fe
Fe
(
)-15: 49%
Advanced NMR studies and X-ray diffraction analyses
revealed similar structures in solution and in the solid state,
probably due to the reduced degree of freedom for steric
reasons (see SI). As a result, all peaks of the 1H NMR spectra
of compounds (±)-4–10 are well resolved while the isopro-
pyl signals are usually broad singlets in the ferrocenecar-
boxamide series. In all studied cases, the phenyl ring ap-
pears tilted relative to the Cp ring while the C=O bond of the
amide always points down toward the iron atom. Further-
more, one methyl of each isopropyl group points toward
the aromatic ring while the other points toward the ferro-
cene moiety. Depending on the substituent on the phenyl
ring, some degree of rotation around the FcC–ArC bond was
noticed.
To complete this study, we finally extended the scope of
the copper-mediated C–O bond formation between 2 and
carboxylic acids. When reacting (±)-2 with a slight excess of
4-fluorobenzoic acid in the presence of Cu2O, (±)-11 was
isolated in 85% yield (Scheme 5). Similarly, from (Sp)-2
(87:13 er), (Sp)-11 was obtained in 76% yield and almost un-
changed er ratio (89:11). Having established the full trans-
fer of chiral information, the reaction between (±)-2 and
other coupling partners was evaluated. 2-Naphthoic, 2,4-
dimethylbenzoic, and 2-acetoxybenzoic acids all afforded
the corresponding esters (±)-12–14 in good yields while
terephthalic acid led to the bis-ester (±)-15 in 49% yield.
The reaction was also found to be compatible with ferro-
cenecarboxylic and 2-thiophenecarboxylic acids [products
(±)-16 and (±)-17, respectively]. However, 2-picolinic acid
and phenylpropiolic acids only led to recovery of starting
O
O
O
S
O
O
CONiPr2
CONiPr2
O
Fe
O
Fe
O
(
)-19: 92%
(
)-17: 77%
O
CONiPr2
O
Fe
(
)-18: 88%
Scheme 5 Ullmann-type cross-coupling between (±)-2 or (Sp)-2 and
various carboxylic acids
In conclusion, we have reported reaction conditions
able to deliver grams of 2-iodo-N,N-diisopropylferrocene-
carboxamide (±)- and (Sp)-2 from cheap ferrocene without
chromatographic purification. Two protocols, one using the
nBuLi-TMEDA chelate and one using LiTMP in the presence
of ZnCl2 as an in situ trap were therefore successfully devel-
oped. Further elaboration through Suzuki–Miyaura or Ull-
mann-type cross-coupling reactions afforded biarylic and
ester derivatives in moderate to good yields.
Unless otherwise stated, all reactions were performed under an argon
atmosphere with anhydrous solvents using Schlenk technics. THF and
Et2O were distilled over Na/benzophenone; MeCN and toluene were
distilled over CaH2. Unless otherwise stated, all reagents were used
without prior purification. All organolithiated reagents were titrated
before use.22 tBuOK (99.99% quality) was purchased from Sigma-Al-
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I

D
W. Erb et al.
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Synthesis
drich and used without further purification. Column chromatography
separations were achieved on silica gel (40–63 m). All TLC analyses
were performed on aluminum backed plates pre-coated with silica gel
(Merck, Silica Gel 60 F254). They were visualized by exposure to UV
light. Melting points were measured on a Kofler bench. IR spectra
were taken on a PerkinElmer Spectrum 100 spectrophotometer. 1H
and 13C NMR spectra were recorded either on a Bruker Avance III
spectrometer at 300 MHz and 75.4 MHz, respectively, or on a Bruker
Avance III HD at 500 MHz and 126 MHz, respectively. 1H chemical
tle product as an orange solid (34.6 g, 94%); mp 208–210 °C (dec.);
Rf = 0.30 (PE/EtOAc 75:25). Analytical data were analogous to those
reported previously.24
IR (film): 2882 (br), 1651, 1474, 1282, 1158, 1029, 936, 914, 834, 740
cm–1
.
1H NMR (500 MHz, DMSO-d6):  =12.15 (br s, 1 H, CO2H), 4.69 (s, 2 H,
2 × FcCH), 4.43 (s, 2 H, 2 × FcCH), 4.21 (s, 5 H, Cp).
13C NMR (126 MHz, DMSO-d6):  = 172.1 (CO2H), 71.8 (FcC), 71.0
(2 × FcCH), 69.9 (2 × FcCH), 69.5 (Cp).
shifts () are given in ppm relative to the solvent residual peak and 13
C
chemical shifts are relative to the central peak of the solvent signal.
Cp refers to the unsubstituted cyclopentadienyl ring on ferrocene.
Optical rotations were recorded at 20 °C on a PerkinElmer 341 po-
larimeter. Enantiomeric ratios (er) were determined by chiral HPLC
on a ThermoFischer Ultimate 3000 apparatus. ZnCl2 was recrystal-
lized from 1,4-dioxane in the presence of Zn dust and dried under
high vacuum at 150 °C overnight. (+)-Sparteine surrogate was pre-
pared according to O’Brien and was distilled over CaH2 before use.16
Piperic acid was prepared according to Singh.23
N,N-Diisopropylferrocenecarboxamide (1)
[CAS Reg. No. 169830-46-0]
Compound 3 (27.6 g, 120 mmol, 1.00 equiv) was introduced into a 1 L
round-bottomed flask equipped with a bubbler and an addition fun-
nel. CH2Cl2 (undried standard quality, 480 mL) and DMF (undried
standard quality, 0.50 mL, 425 mg, 5.80 mmol, 50.0 equiv) were intro-
duced and the resulting orange suspension was stirred at rt. Oxalyl
chloride (25.4 mL, 38.1 g, 300 mmol, 2.50 equiv) was added dropwise
over 20 min. Caution: Evolution of CO and CO2 required to work un-
der a well-ventilated fume hood. After addition, the addition funnel
was washed with CH2Cl2 (10 mL) and the reaction mixture was then
stirred at rt for 30 min. Remark: As the reaction proceeds, the orange
solid slowly dissolves leading to a dark-red solution of FcCOCl. All vol-
atiles were removed under vacuum using a rotary evaporator and the
resulting oil was kept under high vacuum (2 mbar) for 5 min before
being dissolved in CH2Cl2 (undried standard quality, 480 mL). i-Pr2NH
(50.5 mL, 36.4 g, 360 mmol, 3.00 equiv) was added dropwise over 30
min. Caution: A slightly exothermic reaction was noticed, however,
not high enough for solvent boiling. After addition, the mixture was
stirred for an additional 30 min at rt. All volatiles were removed un-
der vacuum using a rotary evaporator and the resulting oil was kept
under high vacuum (2 mbar) for 5 min. Et2O (500 mL) was added and
the mixture was washed with aq 1.0 M HCl (150 mL). Remark: In case
of emulsion formation, filtration over cotton wool can be done. The
aqueous layer was backwashed with Et2O (100 mL). The combined or-
ganic layers were washed with 5% aq NaOH (150 mL), H2O (150 mL),
brine (150 mL), dried (MgSO4), filtered over a pad of Celite (∅ 6, h 4
cm, sintered glass funnel porosity 3) and concentrated under vacuum
to give the crude product. The residue was transferred into a 250 mL
round-bottomed flask using heptane (65 mL). The solution was heat-
ed at reflux, allowed to cool to rt, and then kept at –20 °C overnight.
Using a cannula, the solution was pumped off from the solid which
was washed with cooled pentane (–30 °C, 1 × 15 mL). The resulting
solid was dried under high-vacuum (2 mbar) to give the title product
as an orange solid (35.9 g, 96%); mp 73–75 °C; Rf = 0.65 (PE/EtOAc
75:25). Analytical data analogous to those reported previously.13
X-ray Crystal Data
For details of X-ray crystal data for compounds (Sp)-2, (±)-4, (±)-5,
(±)-6, (±)-7, (±)-9, (±)-10, (±)-11, (±)-13, (±)-14, and (±)-17, see the
Supporting Information.
Safety Considerations
Due to its high pyrophoric character, tBuLi needs to be used only un-
der inert conditions (dry N2 or argon atmosphere) and by people well
trained to the manipulation of reactive organometallics. Due to the
inherent dangers of using cryogenic temperatures, experiments
should be performed by well-trained people.
Ferrocenecarboxylic Acid (3)
[CAS Reg. No. 1271-42-7]
Ferrocene (29.8 g, 160 mmol, 1.00 equiv) and tBuOK (1.79 g, 16.0
mmol, 0.100 equiv) were introduced into a 2 L flame-dried round-
bottomed flask, which was then subjected to three cycles of vacu-
um/argon. Anhyd THF (1.23 L) was introduced by cannula and the re-
action mixture was stirred at rt until dissolution of all solids. The
mixture was cooled between –85 and –80 °C (external temperature)
in an acetone/liquid N2 bath. tBuLi (1.6 M, 320 mmol, 200 mL, 2.00
equiv) was then introduced dropwise by a cannula keeping the tem-
perature of the bath between –85 and –80 °C. After addition, the mix-
ture was stirred at the same temperature for 1 h. Gaseous CO2 (dried
by bubbling through concd H2SO4 and passing through an anhyd CaCl2
column) was bubbled into the reaction mixture for 30 min, keeping
the temperature of the bath between –85 and –80 °C. The mixture
was then allowed to warm to –15 °C, keeping the flask into the bath,
with a continued bubbling of CO2. At –15 °C, bubbling of CO2 was
stopped, the cooling bath was removed, and the mixture was warmed
to rt. H2O (200 mL) was slowly added to the mixture, which was then
extracted with 10% aq NaOH (6 × 150 mL). The combined aqueous lay-
ers were backwashed with Et2O (4 × 250 mL), cooled to 0 °C (ice-water
bath), and acidified with HCl (35%) until pH 1 was reached. Caution:
Vigorous evolution of CO2 occurred upon acidification. The resulting
solids were filtered on a sintered-glass funnel (porosity 3), washed
with H2O (5 × 250 mL) and pentane (1 × 250 mL), wringing the solid
under vacuum between each wash. The resulting solid was dried
overnight under high-vacuum (2 mbar) using P2O5 trap to give the ti-
IR (film): 3084, 2972, 1627, 1463, 1423, 1369, 1317, 1200, 1151,
1135, 1105, 1041, 1025, 823, 806 cm–1
.
1H NMR (500 MHz, CDCl3):  = 4.58 (br s, 1 H, CH), 4.52 (t, J = 1.7 Hz, 2
H, 2 × FcCH), 4.22 (t, J = 1.7 Hz, 2 H, 2 × FcCH), 4.19 (s, 5 H, Cp), 3.38
(br s, 1 H, CH), 1.44 (br s, 6 H, 2 × CH3), 1.18 (br s, 6 H, 2 × CH3).
13C NMR (126 MHz, CDCl3):  = 169.5 (C=O), 81.4 (FcC), 70.1 (2 ×
FcCH), 69.8 (Cp), 68.9 (2 × FcCH), 49.6 (CH), 46.4 (CH), 21.3 (4 × CH3).
MS: m/z = 313 [M], 213 [M – NiPr2].
(±)-2-Iodo-N,N-diisopropylferrocenecarboxamide [(±)-2) by Using
nBuLi-TMEDA
[CAS Reg. No. 344927-04-4]
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W. Erb et al.
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Synthesis
TMEDA (21.0 mL, 16.3 g, 140 mmol, 1.50 equiv, freshly distilled over
CaCl2 and stored over KOH pellets) and anhyd Et2O (430 mL) were in-
troduced into a 2 L flame-dried round-bottomed flask under argon.
The reaction mixture was cooled to between –85 and –80 °C (external
temperature) in an acetone/liquid N2 bath. nBuLi (1.4 M, 100 mL, 140
mmol, 1.50 equiv) was then introduced dropwise by cannula, keeping
the temperature of the bath between –85 and –80 °C. After addition,
the reaction mixture was stirred at the same temperature for 15 min.
Compound 1 (29.2 g, 93.3 mmol, 1.00 equiv) was introduced into a
separate 1 L flame-dried round-bottomed flask, which was subjected
to three cycles of vacuum/argon. Anhyd Et2O (430 mL) was added and
the solution was stirred until dissolution of all solids. The solution of
1 was transferred to the nBuLi-TMEDA solution dropwise by cannula,
keeping the temperature of the bath between –85 and –80 °C. The
flask was washed with anhyd Et2O (10 mL), also transferred by cannu-
la. After addition, the reaction mixture was stirred at the same tem-
perature for 1 h. I2 (47.4 g, 187 mmol, 2.00 equiv) was introduced in a
separate 1 L flame-dried round-bottomed flask under argon and was
dissolved into anhyd Et2O (800 mL). The iodine solution was trans-
ferred to the lithioferrocene solution dropwise by cannula, keeping
the temperature of the bath between –85 and –80 °C. The flask was
washed with anhyd Et2O (10 mL), also transferred by cannula. The
mixture was then allowed to warm to –15 °C, keeping the flask into
the bath. At –15 °C, the cooling bath was removed and the mixture
was warmed to rt. Remark: At this stage, the reaction mixture can be
kept at –20 °C overnight before workup, if required. Half of the sol-
vent was removed under vacuum and EtOAc (800 mL) was added. The
mixture was washed with sat. aq Na2S2O3 (2 × 150 mL), H2O (2 × 150
mL) and brine (1 × 150 mL), dried (MgSO4), filtered over cotton wool,
and concentrated under vacuum using a rotary evaporator. The re-
sulting oil was dissolved in hot heptane/EtOAc (80:20) solution and
was hot filtered over a pad of silica gel (∅ 6, h 4 cm, sintered glass
funnel porosity 3), which was washed with the same hot solvent until
the filtrate was colorless. The filtrate was then concentrated under
vacuum using a rotary evaporator to give the crude product. This was
dissolved into heptane (100 mL), the solution was heated at reflux, al-
lowed to cool to rt, and then kept at –20 °C overnight. Using a cannu-
la, the solution was pumped off from the solid, which was washed
with cold pentane (–30 °C, 2 × 40 mL). The solution was pumped off
using a cannula. The resulting solid was dried under high-vacuum (2
mbar) to give the title product as an orange solid (35.9 g, 88%); mp
137–139 °C; Rf = 0.68 (PE/EtOAc 80:20). Analytical data analogous to
those reported previously.13
to –30 °C and was cannulated onto a solution of compound 1 (15.7 g,
50.0 mmol, 1.00 equiv) and ZnCl2 (6.81 g, 50.0 mmol, 1.00 equiv) in
THF (100 mL) at –30 °C, followed by a THF (10 mL) washing of the
flask containing LiTMP. The mixture was warmed to –10 °C over 2 h
and a solution of I2 (25.4 g, 100 mmol, 2.00 equiv) in THF (130 mL)
was added by cannula, followed by a THF (10 mL) washing of the flask
containing the I2 solution. The cooling bath was removed and the re-
action mixture was warmed to rt. Half of the solvent was removed
under vacuum and EtOAc (430 mL) was added. By following a similar
workup procedure as the one described before, adjusting the quanti-
ties, the title product was obtained as an orange solid (20.5 g, 93%).
Analytical data analogous to those reported above.
(Sp)-2-Iodo-N,N-diisopropylferrocenecarboxamide [(Sp)-2]
(+)-Sparteine surrogate (1.16 g, 6.00 mmol, 1.30 equiv) and anhyd
Et2O (70 mL) were introduced into a 250 mL flame-dried round-bot-
tomed flask under argon. The reaction mixture was cooled to be-
tween –85 and –80 °C (external temperature) in an acetone/liquid N2
bath. nBuLi (1.4 M, 4.30 mL, 6.00 mmol, 1.30 equiv) was then intro-
duced dropwise by a syringe, keeping the temperature of the bath be-
tween –85 and –80 °C. After addition, the mixture was stirred at the
same temperature for 30 min. Compound 1 (1.40 g, 4.50 mmol, 1.00
equiv) was introduced into a separate 20 mL flame-dried round-bot-
tomed flask, which was subjected to three cycles of vacuum/argon.
Anhyd toluene (10.0 mL) was added and the solution was stirred until
dissolution of all solids had occurred. The solution of 1 was trans-
ferred to the nBuLi/(+)-sparteine surrogate solution dropwise by can-
nula, keeping the temperature of the bath between –85 and –80 °C.
The flask was washed with anhyd Et2O (2 mL), also transferred by
cannula. After addition, the mixture was stirred at the same tempera-
ture for 2 h. I2 (2.30 g, 9.00 mmol, 2.00 equiv) was introduced into a
separate 100 mL flame-dried round-bottomed flask under argon and
was dissolved in anhyd Et2O (60 mL). The I2 solution was transferred
to the lithioferrocene solution dropwise by cannula, keeping the tem-
perature of the bath between –85 and –80 °C. The flask was washed
with anhyd Et2O (5 mL), also transferred by cannula. The reaction
mixture was then allowed to warm to –15 °C, keeping the flask into
the bath. At –15 °C, the cooling bath was removed and the mixture
was warmed to rt. Sat. aq Na2S2O3 (100 mL), EtOAc (100 mL), and H2O
(50 mL) were added to the mixture, the layers were separated, and the
aqueous one was backwashed with EtOAc (50 mL). The organic layer
was washed with aq 5% H3PO4 (3 × 30 mL) and the combined aqueous
layers were backwashed with EtOAc (50 mL). The combined organic
layers were washed with H2O (2 × 50 mL) and brine (1 × 50 mL), dried
(MgSO4), filtered over cotton wool, and concentrated under vacuum
using a rotary evaporator to give the crude product. This was purified
by column chromatography over SiO2, using PE/EtOAc (10:1 to 9:1) to
give the title product as an orange oil (1.4 g, 69%, 96:4 er); []D –87.9
(c 0.01, CHCl3). Analytical data analogous to racemic compound.
IR (film): 2971, 1619, 1456, 1368, 1315, 1298, 1206, 1036, 811, 686
cm–1
.
1H NMR (500 MHz, CDCl3):  = 4.36 (q, J = 1.7, 1.1 Hz, 1 H, FcCH), 4.28
(s, 5 H, Cp), 4.22 (q, J = 2.0, 1.1 Hz, 1 H, FcCH), 4.11 (t, J = 2.4 Hz, 1 H,
FcCH), 3.55 (t, J = 5.5 Hz, 1 H, CH), 3.33 (t, J = 5.5 Hz, 1 H, CH), 1.45 (s,
6 H, 2 × CH3), 1.03 (d, J = 5.5 Hz, 3 H, CH3), 0.92 (d, J = 5.5 Hz, 3 H, CH3).
13C NMR (126 MHz, CDCl3):  = 166.3 (C=O), 92.6 (FcC), 73.6 (FcCH),
72.7 (Cp), 67.6 (FcCH), 66.8 (FcCH), 50.8 (CH), 45.9 (CH), 40.5 (FcC–I),
21.0 (2 × CH3), 20.8 (CH3), 20.7 (CH3).
The enantiomeric ratio was determined on a Chiralpak IC-3 column:
Hexane/iPrOH (98:2), 1.5 mL/min, 20 °C,  = 254 nm, tR (major) =
10.19 min, tR (minor) = 7.64 min. Recrystallization from hot heptane
as described for the racemic product increased the er to 99:1 as deter-
mined by chiral HPLC.
MS: m/z = 439 [M], 311 [M – CONiPr2], 268.
Suzuki–Miyaura Cross-Coupling of (±)-2; General Procedure A
(±)-2-Iodo-N,N-diisopropylferrocenecarboxamide [(±)-2] by Using
Compound (±)-2 (242 mg, 0.55 mmol, 1.00 equiv), arylboronic acid
(2.20 mmol, 4.00 equiv), Pd(dba)2 (15.8 mg, 27.5 mol, 5 mol%), CsF
(167 mg, 1.10 mmol, 2.00 equiv), and PPh3 (28.5 mg, 0.11 mmol, 0.20
equiv) were placed in a dried Schlenk tube, subjected to three cycles
of vacuum/argon. Toluene (5 mL) was added and the reaction mixture
was stirred overnight at 120 °C (external temperature) in a pre-heat-
LiTMP-ZnCl2
[CAS Reg. No. 344927-04-4]
nBuLi (1.4 M, 71.4 mL, 100 mmol, 2.00 equiv) was added dropwise by
cannula to a solution of TMPH (16.9 mL, 14.1 g, 100 mmol, 2.00 equiv)
in THF (80 mL) at –20 °C. After addition, the reaction mixture was
stirred at the same temperature for 10 min. The mixture was cooled
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I

F
W. Erb et al.
PSP
Synthesis
ed oil bath. The mixture was cooled to rt, H2O (10 mL) was added and
the mixture was extracted with EtOAc (2 × 10 mL). The combined or-
ganic layers were dried (MgSO4), filtered over cotton wool, and con-
centrated under vacuum using a rotary evaporator to give the crude
product. This was purified by column chromatography over SiO2, us-
ing PE/EtOAc (proportions given for each product) to give the title
product.
IR (film): 2964, 1625, 1505, 1450, 1341, 1310, 122, 1037, 1104, 809,
735 cm–1
.
1H NMR (500 MHz, CDCl3):  = 7.43 (d, J = 2.6 Hz, 1 H, ArCH), 6.75–
6.70 (m, 2 H, 2 × ArCH), 4.63 (dd, J = 1.5, 2.3 Hz, 1 H, FcCH), 4.41 (dd,
J = 1.5, 2.2 Hz, 1 H, FcCH), 4.26 (s, 5 H, Cp), 4.25 (t, J = 2.2 Hz, 1 H,
FcCH), 3.79 (s, 3 H, OCH3), 3.71 (s, 3 H, OCH3), 3.53 (sept, J = 6.7 Hz, 1
H, CH), 3.16 (sept, J = 6.7 Hz, 1 H, CH), 1.45 (d, J = 6.7 Hz, 3 H, CH3),
1.32 (d, J = 6.7 Hz, 3 H, CH3), 0.82 (d, J = 6.7 Hz, 3 H, CH3), 0.28 (d, J =
6.7 Hz, 3 H, CH3).
(±)-N,N-Diisopropyl-2-phenylferrocenecarboxamide [(±)-4]
13C NMR (126 MHz, CDCl3):  = 168.2 (C=O), 153.3 (ArC–O), 151.5
(ArC–O), 127.1 (ArC), 117.4 (ArCH), 113.5 (ArCH), 112.1 (ArCH), 90.8
(FcC–CO), 81.5 (FcC), 71.3 (Cp), 69.0 (FcCH), 68.7 (FcCH), 66.7 (FcCH),
56.1 (OCH3), 55.8 (OCH3), 50.6 (CH), 45.7 (CH), 21.2 (CH3), 21.1 (CH3),
20.3 (CH3), 19.7 (CH3).
By following the general procedure A, using phenylboronic acid (268
mg), (±)-4 was obtained after column chromatography (PE/EtOAc
90:10) as an orange solid (125 mg, 59%); mp 134–136 °C; Rf = 0.54
(PE/EtOAc 90:10).
IR (film): 2965, 1626, 1463, 1442, 1343, 1317, 1304, 1215, 1136,
1105, 1035, 818, 765, 698 cm–1
.
MS: m/z = 449 [M], 349 [M – NiPr2].
1H NMR (500 MHz, CDCl3):  = 7.52 (d, J = 8.0 Hz, 2 H, 2 × ArCH), 8.23
(m, 2 H, 2 × ArCH), 7.17 (d, J = 7.1 Hz, 1 H, ArCH), 4.45 (dd, J = 1.4, 2.0
Hz, 1 H, FcCH), 4.41 (dd, J = 1.4, 2.0 Hz, 1 H, FcCH), 4.24–4.23 (m, 6 H,
Cp + FcCH), 3.47 (sept, J = 6.7 Hz, 1 H, CH), 3.19 (sept, J = 6.8 Hz, 1 H,
CH), 1.47 (d, J = 6.8 Hz, 3 H, CH3), 1.38 (d, J = 6.8 Hz, 3 H, CH3), 0.81 (d,
J = 6.7 Hz, 3 H, CH3), 0.24 (d, J = 6.7 Hz, 3 H, CH3).
(±)-N,N-Diisopropyl-2-(2-naphthyl)ferrocenecarboxamide [(±)-7]
By following the general procedure A, using 2-naphthylboronic acid
(378 mg), (±)-7 was obtained after column chromatography (PE/EtOAc
90:10) as an orange solid (156 mg, 65%); mp 218–220 °C; Rf = 0.43
(PE/EtOAc 90:10).
13C NMR (126 MHz, CDCl3):  = 168.2 (C=O), 138.3 (ArC), 128.3 (2 ×
ArCH), 128.2 (2 × ArCH), 126.7 (ArCH), 90.1 (FcC–CO), 84.9 (FcC), 71.4
(Cp), 69.8 (FcCH), 67.0 (FcCH), 64.9 (FcCH), 50.8 (CH), 45.9 (CH), 21.4
(CH3), 21.1 (CH3), 19.9 (CH3), 19.5 (CH3).
IR (film): 2966, 1622, 1462, 1334, 1303, 1201, 1134, 1040, 864, 820,
808, 755 cm–1
.
1H NMR (500 MHz, CDCl3):  = 7.94 (s, 1 H, ArCH), 7.78–7.74 (m, 2 H,
2 × ArCH), 7.74 (m, 2 H, 2 × ArCH), 7.45–7.40 (m, 2 H, 2 × ArCH), 4.61
(dd, J = 1.5, 2.3 Hz, 1 H, FcCH), 4.49 (dd, J = 1.4, 2.3 Hz, 1 H, FcCH), 4.32
(t, J = 2.3 Hz, 1 H, FcCH), 3.55 (sept, J = 6.7 Hz, 1 H, CH), 3.20 (sept, J =
6.8 Hz, 1 H, CH), 1.52 (d, J = 6.8 Hz, 3 H, CH3), 1.43 (d, J = 6.8 Hz, 3 H,
CH3), 0.84 (d, J = 6.7 Hz, 3 H, CH3), 0.19 (d, J = 6.7 Hz, 3 H, CH3).
MS: m/z = 389 [M], 289 [M – NiPr2].
(±)-N,N-Diisopropyl-2-(4-methoxyphenyl)ferrocenecarboxamide
[(±)-5]
13C NMR (126 MHz, CDCl3):  = 168.3 (C=O), 136.1 (ArC), 133.6 (ArC),
132.5 (ArC), 127.9 (ArCH), 127.8 (ArCH), 127.7 (ArCH), 127.1 (ArCH),
126.4 (ArCH), 125.8 (ArCH), 125.6 (ArCH), 90.3 (FcC–CO), 84.5 (FcC),
71.5 (Cp), 70.2 (FcCH), 67.3 (FcCH), 65.0 (FcCH), 50.9 (CH), 45.9 (CH),
21.4 (CH3), 21.1 (CH3), 20.0 (CH3), 19.8 (CH3).
By following the general procedure A, using 4-methoxyphenylboronic
acid (334 mg), (±)-5 was obtained after column chromatography
(PE/EtOAc 10:1) as an orange solid (197 mg, 77%); mp 142–144 °C;
Rf = 0.57 (PE/EtOAc 80:20).
IR (film): 2962, 2931, 1625, 1460, 1437, 1341, 1314, 1305, 1289,
1243, 1106, 1027, 906, 845, 815, 734 cm–1
.
MS: m/z = 439 [M], 339 [M – NiPr2].
1H NMR (500 MHz, CDCl3):  = 7.45 (d, J = 8.8 Hz, 2 H, 2 × ArCH), 6.79
(d, J = 8.8 Hz, 2 H, 2 × ArCH), 4.41 (dd, J = 1.5, 2.2 Hz, 1 H, FcCH), 4.38
(dd, J = 1.5, 2.2 Hz, 1 H, FcCH), 4.23 (s, 5 H, Cp), 4.20 (t, J = 2.2 Hz, 1 H,
FcCH), 3.78 (s, 3 H, OCH3), 3.48 (sept, J = 6.7 Hz, 1 H, CH), 3.20 (sept,
J = 6.7 Hz, 1 H, CH), 1.48 (d, J = 6.7 Hz, 3 H, CH3), 1.38 (d, J = 6.7 Hz, 3 H,
CH3), 0.83 (d, J = 6.7 Hz, 3 H, CH3), 0.30 (d, J = 6.7 Hz, 3 H, CH3).
13C NMR (126 MHz, CDCl3):  = 168.3 (C=O), 158.6 (ArC–O), 130.4
(ArC), 129.3 (2 × ArCH), 113.7 (2 × ArCH), 89.3 (FcC–CO), 85.1 (FcC),
71.3 (Cp), 69.4 (FcCH), 66.6 (FcCH), 64.9 (FcCH), 55.4 (OCH3), 50.8
(CH), 45.8 (CH), 21.3 (CH3), 21.0 (CH3), 19.9 (CH3), 19.7 (CH3).
(±)-2-(2-Chlorophenyl)-N,N-diisopropylferrocenecarboxamide
[(±)-8]
By following the general procedure A, using 2-chlorophenylboronic
acid (344 mg), (±)-8 was obtained after column chromatography
(PE/EtOAc 10:1) as an orange solid (29.2 mg, 11%); mp 82–84 °C; Rf =
0.34 (PE/EtOAc 90:10).
IR (film): 2994, 2960, 2929, 1621, 1461, 1437, 1368, 1339, 1305,
1212, 1195, 1157, 1136, 1035, 1023, 1003, 813, 749 cm–1
.
1H NMR (500 MHz, CDCl3):  = 8.03 (dd, J = 1.5, 7.8 Hz, 1 H, ArCH),
7.29 (dd, J = 0.8, 7.8 Hz, 1 H, ArCH), 7.22 (dt, J = 1.1, 7.7 Hz, 1 H, ArCH),
7.16 (dt, J = 1.5, 7.7 Hz, 1 H, ArCH), 4.70 (dd, J = 1.0, 2.0 Hz, 1 H, FcCH),
4.46 (dd, J = 1.4, 2.0 Hz, 1 H, FcCH), 4.31 (t, J = 2.4 Hz, 1 H, FcCH), 4.29
(s, 5 H, Cp), 3.51 (sept, J = 6.6 Hz, 1 H, CH), 3.13 (sept, J = 6.8 Hz, 1 H,
CH), 1.44 (d, J = 6.8 Hz, 3 H, CH3), 1.21 (d, J = 6.8 Hz, 3 H, CH3), 0.85 (d,
J = 6.6 Hz, 3 H, CH3), 0.30 (d, J = 6.6 Hz, 3 H, CH3).
13C NMR (126 MHz, CDCl3):  = 167.6 (C=O), 135.9 (ArC), 134.0 (ArCH),
133.5 (ArC), 129.6 (ArCH), 128.0 (ArCH), 126.4 (ArCH), 91.9 (FcC–CO),
83.2 (FcC), 71.5 (Cp), 68.9 (FcCH), 68.8 (FcCH), 66.6 (FcCH), 50.7 (CH),
45.8 (CH), 21.3 (CH3), 21.2 (CH3), 19.9 (CH3), 19.6 (CH3).
MS: m/z = 491 [M], 319 [M – NiPr2].
(±)-N,N-Diisopropyl-2-(2,4-dimethoxyphenyl)ferrocenecarboxam-
ide [(±)-6]
[CAS Reg. No. 173911-02-9]
By following the general procedure A, using 2,4-dimethoxyphenylbo-
ronic acid (400 mg), (±)-6 was obtained after column chromatography
(PE/EtOAc 10:1) as an orange solid (174 mg, 64%); mp 163–166 °C;
Rf = 0.59 (PE/EtOAc 80:20). Analytical data analogous to those report-
ed previously.7
MS: m/z = 313 [M – C6H4Cl + H], 213 [FcCO2H].
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I

G
W. Erb et al.
PSP
Synthesis
(±)-2-(3-Chlorophenyl)-N,N-diisopropylferrocenecarboxamide
[(±)-9]
IR (film): 2967, 1744, 1736, 1632, 1598, 1507, 1471, 1435, 1371,
1321, 1262, 1246, 1224, 1155, 1134, 1081, 1063, 1041, 1012, 1003,
866, 812, 763, 757, 686 cm–1
.
By following the general procedure A, using 3-chlorophenylboronic
acid (344 mg), (±)-9 was obtained after column chromatography
(PE/EtOAc 10:1) as an orange solid (66.6 mg, 29%); mp 133–135 °C;
Rf = 0.46 (PE/EtOAc 90:10).
1H NMR (300 MHz, CDCl3):  = 8.10 (dd, J = 5.5, 8.9 Hz, 2 H, 2 × ArCH),
7.11 (t, J = 8.6 Hz, 2 H, 2 × ArCH), 4.64 (dd, J = 1.5, 2.6 Hz, 1 H, FcCH),
4.38 (s, 5 H, Cp), 4.12 (dd, J = 1.5, 2.7 Hz, 1 H, FcCH), 4.06 (br s, 1 H,
CH), 4.00 (t, J = 2.7 Hz, 1 H, FcCH), 3.36 (br s, 1 H, CH), 1.45 (br s, 3 H,
CH3), 1.37 (br s, 3 H, CH3), 1.05 (br s, 3 H, CH3), 0.99 (br s, 3 H, CH3).
IR (film): 2972, 1617, 1597, 1461, 1439, 1368, 1341, 1310, 1196,
1136, 1055, 1039, 1005, 819, 810, 798, 768, 687 cm–1
.
13C NMR (75.4 MHz, CDCl3):  = 166.2 (d, J = 254.7 Hz, ArC–F), 165.8
(s, C=Oamide), 164.4 (s, C=Oester), 132.7 (d, J = 9.4 Hz, 2 × ArCH), 126.0 (d,
J = 2.8 Hz, ArC), 115.9 (d, J = 22.2 Hz, 2 × ArCH), 115.2 (s, FcC–O), 80.1
(s, FcC), 71.4 (s, Cp), 62.8 (s, FcCH), 62.1 (s, FcCH), 61.1 (s, FcCH), 50.7
(s, CH), 46.1 (s, CH), 20.8 (s, 4 × CH3).
1H NMR (500 MHz, CDCl3):  = 7.51 (t, J = 1.8 Hz, 1 H, ArCH), 7.42 (dt,
J = 1.9, 6.6 Hz, 1 H, ArCH), 7.17 (d, J = 4.7 Hz, 1 H, ArCH), 7.16 (t, J = 1.8
Hz, 1 H, ArCH), 4.45 (m, 1 H, FcCH), 4.44 (m, 1 H, FcCH), 4.28 (t, J = 2.4
Hz, 1 H, FcCH), 4.25 (s, 5 H, Cp), 3.47 (sept, J = 6.7 Hz, 1 H, CH), 3.24
(sept, J = 6.8 Hz, 1 H, CH), 1.50 (d, J = 6.8 Hz, 3 H, CH3), 1.42 (d, J = 6.8
Hz, 3 H, CH3), 0.85 (d, J = 6.7 Hz, 3 H, CH3), 0.35 (d, J = 6.7 Hz, 3 H, CH3).
MS: m/z = 451 [M], 328, 229.
13C NMR (126 MHz, CDCl3):  = 167.8 (C=O), 140.7 (ArC), 134.2 (ArC),
129.5 (ArCH), 127.9 (ArCH), 126.7 (ArCH), 126.3 (ArCH), 90.3 (FcC–
CO), 83.2 (FcC), 71.6 (Cp), 70.1 (FcCH), 67.4 (FcCH), 64.9 (FcCH), 50.9
(CH), 46.0 (CH), 21.3 (CH3), 21.1 (CH3), 20.0 (CH3), 19.7 (CH3).
(Sp)-N,N-Diisopropyl-2-(4-fluorobenzoyl)ferrocenecarboxamide
[(Sp)-11]
By following the general procedure B, using (Sp)-2-iodo-N,N-diisopro-
pylferrocenecarboxamide (er 87:13, 80.0 mg) and 4-fluorobenzoic
acid (30.3 mg), (Sp)-11 was obtained after column chromatography
(PE/EtOAc 10:1 to 90:10, 1% of NEt3) as an orange solid (62 mg, 76%,
89:11 er); []D –1.09 (c 0.01 in CHCl3).
MS: m/z = 423 [M], 323 [M – NiPr2], 296 [M – CONiPr2 + H].
(±)-N,N-Diisopropyl-2-(4-trifluoromethylphenyl)ferrocenecar-
boxamide [(±)-10]
The enantiomeric ratio was determined on Chiralpak IC-3 column:
Hexane/iPrOH (98:2), 1.0 mL/min, 20 °C,  = 254 nm, tR (major) =
16.50 min, tR (minor) = 19.41 min.
By following the general procedure A, using 4-(trifluoromethyl)phen-
ylboronic acid (417 mg), (±)-10 was obtained after column chroma-
tography (PE/EtOAc 10:1) as an orange solid (52.0 mg, 21%); mp 179–
181 °C; Rf = 0.50 (PE/EtOAc 90:10).
(±)-N,N-Diisopropyl-2-(2-naphthoyl)ferrocenecarboxamide [(±)-
12]
IR (film): 2965, 2932, 2234, 1613, 1463, 1319, 1162, 1121, 1106,
1068, 906, 818, 727 cm–1
.
By following the general procedure B, using 2-naphthoic acid (126
mg), (±)-12 was obtained after column chromatography (PE/EtOAc
10:1 to 90:10, 1% of NEt3) as an orange solid (290 mg, quant); mp
145–147 °C; Rf = 0.43 (PE/EtOAc 90:10).
1H NMR (500 MHz, CDCl3):  = 7.65 (d, J = 8.0 Hz, 2 H, 2 × ArCH), 7.49
(d, J = 8.0 Hz, 2 H, 2 × ArCH), 4.50 (s, 1 H, FcCH), 4.47 (s, 1 H, FcCH),
4.32 (s, 1 H, FcH), 4.25 (s, 5 H, Cp), 3.48 (sept, J = 6.7 Hz, 1 H, CH), 3.25
(sept, J = 6.7 Hz, 1 H, CH), 1.50 (d, J = 6.7 Hz, 3 H, CH3), 1.40 (d, J = 6.7
Hz, 3 H, CH3), 0.87 (d, J = 6.7 Hz, 3 H, CH3), 0.34 (d, J = 6.7 Hz, 3 H, CH3).
13C NMR (126 MHz, CDCl3):  = 167.8 (s, C=O), 142.9 (s, ArC), 128.6 (q,
J = 32.6 Hz, ArC–CF3), 128.2 (s, 2 × ArCH), 124.5 (q, J = 271.9 Hz, CF3),
125.2 (q, J = 3.5 Hz, 2 × ArCH), 90.7 (s, FcC–CO), 82.9 (s, FcC), 71.7 (s,
Cp), 70.3 (s, FcCH), 67.6 (s, FcCH), 65.1 (s, FcCH), 50.9 (s, CH), 46.0 (s,
CH), 21.3 (s, CH3), 21.0 (s, CH3), 20.1 (s, CH3), 19.8 (s, CH3).
IR (film): 2978, 1732, 1626, 1472, 1429, 1318, 1265, 1217, 1189,
1134, 1082, 1004, 951, 876, 834, 814, 778 cm–1
.
1H NMR (300 MHz, CDCl3):  = 8.67 (s, 1 H, ArCH), 8.10 (dd, J = 1.7, 8.6
Hz, 1 H, ArCH), 7.96 (d, J = 8.6 Hz, 1 H, ArCH), 7.89 (d, J = 6.2 Hz, 1 H,
ArCH), 7.87 (d, J = 5.4 Hz, 1 H, ArCH), 7.56 (m, 2 H, 2 × ArCH), 4.75 (dd,
J = 1.4, 2.5 Hz, 1 H, FcCH), 4.43 (s, 5 H, Cp), 4.16 (dd, J = 1.4, 2.5 Hz, 1 H,
FcCH), 4.08 (br s, 1 H, CH), 4.04 (t, J = 2.7 Hz, 1 H, FcCH), 3.39 (br s, 1 H,
CH), 1.47 (br s, 6 H, 2 × CH3), 1.02 (br s, 6 H, 2 × CH3).
13C NMR (75.4 MHz, CDCl3):  = 165.8 (s, C=Oamide), 165.4 (s, C=Oester),
135.9 (ArC), 132.7 (ArC), 131.8 (ArCH), 129.7 (ArCH), 128.7 (ArCH),
128.5 (ArCH), 127.9 (ArCH), 126.9 (ArCH), 125.5 (ArCH), 114.9 (FcC–
O), 80.6 (FcC), 71.4 (Cp), 62.9 (FcCH), 62.1 (FcCH), 61.0 (FcCH), 50.7
(CH), 46.1 (CH), 20.9 (4 × CH3).
19F NMR (282 MHz, CDCl3):  = –62.4 (s).
MS: m/z = 457 [M], 357 [M – NiPr2], 330 [M – CONiPr2 + H].
Ullmann-Type Cross-Coupling of (±)-2; General Procedure B
Compound (±)-2 (263 mg, 0.60 mmol, 1.00 equiv), carboxylic acid
(0.72 mmol, 1.20 equiv), and Cu2O (103 mg, 0.72 mmol, 1.20 equiv)
were placed in a dried Schlenk tube, subjected to three cycles of vacu-
um/argon. MeCN (8.50 mL) was added and the reaction mixture was
stirred overnight at 90 °C (external temperature) in a pre-heated oil
bath. The mixture was cooled to rt, filtered over a pad of Celite,
washed with EtOAc until colorless. The filtrate was concentrated un-
der vacuum using a rotary evaporator to give the crude product. This
was purified by column chromatography over SiO2, using PE/EtOAc
(proportions given for each product) to give the title product.
MS: m/z = 313 [M – C11H7O2 + H].
(±)-N,N-Diisopropyl-2-(2,4-dimethylbenzoyl)ferrocenecarboxam-
ide [(±)-13]
By following the general procedure B, using 2,4-dimethylbenzoic acid
(108 mg), (±)-13 was obtained after column chromatography (PE/EtO-
Ac 90:10, 1% of NEt3) as an orange solid (242 mg, 87%); mp 152–
154 °C; Rf = 0.28 (PE/EtOAc 10:1).
(±)-N,N-Diisopropyl-2-(4-fluorobenzoyl)ferrocenecarboxamide
IR (film): 2958, 1715,1620, 1463, 1430, 1323, 1288, 1252, 1236 cm–1
.
[(±)-11]
1H NMR (300 MHz, CDCl3):  = 7.95 (d, J = 8.4 Hz, 1 H, ArCH), 7.07–
7.05 (m, 2 H, 2 × ArCH), 4.60 (dd, J = 1.5, 2.6 Hz, 1 H, FcCH), 4.39 (s, 5
H, Cp), 4.12 (dd, J = 1.5, 2.6 Hz, 1 H, FcCH), 4.06 (br s, 1 H, CH), 4.00 (t,
By following the general procedure B, using 4-fluorobenzoic acid (101
mg), (±)-11 was obtained after column chromatography (PE/EtOAc
10:1 to 90:10, 1% of NEt3) as an orange solid (230 mg, 85%); mp 142–
144 °C; Rf = 0.50 (PE/EtOAc 90:10).
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I

H
W. Erb et al.
PSP
Synthesis
J = 2.6 Hz, 1 H, FcCH), 3.35 (br s, 1 H, CH), 2.59 (s, 3 H, CH3), 2.34 (s, 3
H, CH3), 1.46 (br s, 3 H, CH3), 1.38 (br s, 3 H, CH3), 1.03 (br s, 3 H, CH3),
0.98 (br s, 3 H, CH3).
13C NMR (75.4 MHz, CDCl3):  = 166.2 (C=O), 165.9 (C=O), 143.3 (ArC),
141.0 (ArC), 132.7 (ArCH), 131.7 (ArCH), 126.8 (ArCH), 125.9 (ArC),
114.9 (FcC–O), 80.7 (FcC), 71.3 (Cp), 62.8 (FcCH), 62.1 (FcCH), 61.2
(FcCH), 50.7 (CH), 46.0 (CH), 22.0 (CH3), 21.6 (CH3), 20.8 (2 × CH3).
IR (film): 2959, 1727, 1626, 1467, 1429, 1374, 1317, 1267, 1245,
1134, 1104, 1027, 1002, 910, 817, 804 cm–1
.
1H NMR (300 MHz, CDCl3):  = 4.85 (m, 1 H, FcCH), 4.83 (m, 1 H,
FcCH), 4.61 (dd, J = 1.5, 2.5 Hz, 1 H, FcCH), 4.43 (t, J = 1.7 Hz, 2 H, 2 ×
FcCH), 4.39 (s, 5 H, Cp), 4.28 (s, 5 H, Cp), 4.09 (dd, J = 1.5, 2.5 Hz, 1 H,
FcCH), 4.02 (br s, 1 H, CH), 3.98 (t, J = 2.5 Hz, 1 H, FcCH), 3.40 (br s, 1 H,
CH), 1.50 (br s, 6 H, 2 × CH3), 1.05 (br s, 6 H, 2 × CH3).
MS: m/z = 461 [M].
13C NMR (75.4 MHz, CDCl3):  = 169.7 (2 × C=Oester), 165.7 (C=Oamide),
114.5 (FcC–O), 80.2 (FcC–COamide), 71.7 (2 × FcCH), 71.1 (Cp), 70.4 (2 ×
FcCH), 70.3 (FcC–COester), 70.0 (Cp), 62.5 (FcCH), 61.9 (FcCH), 60.6
(FcCH), 50.6 (CH), 45.8 (CH), 21.0 (4 × CH3).
(±)-2-(2-Acetoxyphenyl)-N,N-diisopropylferrocenecarboxamide
[(±)-14]
By following the general procedure B, using 2-acetoxybenzoic acid
(130 mg), (±)-14 was obtained after column chromatography (PE/EtO-
Ac 10:1 to 90:10, 1% of NEt3) as an orange solid (212 mg, 72%); mp
157–159 °C; Rf = 0.42 (PE/EtOAc 90:10).
(±)-N,N-Diisopropyl-2-(2-thiophenoyl)ferrocenecarboxamide [(±)-
17]
By following the general procedure B, using 2-thiophenecarboxylic
acid (92.3 mg), (±)-17 was obtained after column chromatography
(PE/EtOAc 10:1, 1% of NEt3) as an orange solid (204 mg, 77%); mp
118–120 °C; Rf = 0.40 (PE/EtOAc 90:10).
IR (film): 2966, 1764, 1736, 1624, 1604, 1474, 1431, 1321, 1242,
1212, 1182, 1156, 1051, 1002, 911, 818, 754, 696 cm–1
.
1H NMR (300 MHz, CDCl3):  = 8.13 (dd, J = 1.7, 7.8 Hz, 1 H, ArCH),
7.56 (dt, J = 1.7, 7.8 Hz, 1 H, ArCH), 7.32 (dt, J = 1.7, 7.8 Hz, 1 H, ArCH),
7.09 (dd, J = 1.7, 7.8 Hz, 1 H, ArCH), 4.56 (dd, J = 1.4, 2.5 Hz, 1 H, FcCH),
4.38 (s, 5 H, Cp), 4.12 (dd, J = 1.4, 2.6 Hz, 1 H, FcCH), 4.04 (br s, 1 H,
CH), 4.00 (t, J = 2.6 Hz, 1 H, FcCH), 3.34 (br s, 1 H, CH), 2.34 (CH3), 1.44
(br s, 3 H, CH3), 1.38 (br s, 3 H, CH3), 1.02 (br s, 3 H, CH3), 0.96 (br s, 3
H, CH3).
13C NMR (75.4 MHz, CDCl3):  = 169.6 (C=Oacetate), 165.6 (C=Oamide),
163.1 (C=Oester), 151.1 (ArC), 134.5 (ArCH), 132.3 (ArCH), 126.3 (ArCH),
124.1 (ArCH), 122.6 (ArC–O), 114.7 (FcC–O), 80.4 (FcC), 71.3 (Cp), 62.9
(FcCH), 62.1 (FcCH), 61.2 (FcCH), 50.6 (CH), 46.0 (CH), 21.2 (CH3), 20.7
(2 × CH3).
IR (film): 2966, 1721, 1632, 1615, 1463, 1410, 1357, 1317, 1247,
1223, 1208, 1079, 1057, 1038, 1022, 1001, 812, 742, 735 cm–1
.
1H NMR (300 MHz, CDCl3):  = 7.86 (dd, J = 1.3, 3.8 Hz, 1 H, ArCH),
7.59 (dd, J = 1.3, 5.0 Hz, 1 H, ArCH), 7.11 (dd, J = 3.8, 5.0 Hz, 1 H, ArCH),
4.66 (dd, J = 1.5, 2.6 Hz, 1 H, FcCH), 4.11 (dd, J = 1.5, 2.6 Hz, 1 H, FcCH),
4.04 (br s, 1 H, CH), 3.99 (t, J = 2.6 Hz, 1 H, FcCH), 3.38 (br s, 1 H, CH),
1.44 (br s, 6 H, 2 × CH3), 1.02 (br s, 6 H, 2 × CH3).
13C NMR (75.4 MHz, CDCl3):  = 165.6 (C=Oamide), 160.5 (C=Oester),
134.4 (ArCH), 133.5 (ArCH), 13.1 (ArC), 128.1 (ArCH), 114.6 (FcC–CO),
80.4 (FcC), 71.4 (Cp), 62.9 (FcCH), 62.1 (FcCH), 60.7 (FcCH), 50.7 (CH),
46.0 (CH), 20.8 (4 × CH3).
MS: m/z = 491 [M], 329 [M – C9H7O3 + H].
MS: m/z = 439 [M], 328, 229.
Bis (±)-N,N-Diisopropyl-2-(1,4-phenyldioyl)ferrocenecarboxam-
(±)-N,N-Diisopropyl-2-(3,4-methylenedioxycinnamoyl)ferrocene-
ide [(±)-15]
carboxamide [(±)-18]
By following the general procedure B, using terephthalic acid (49.8
mg, 0.30 mmol, 0.50 equiv), (±)-15 was obtained after column chro-
matography (PE/EtOAc 10:1 to 90:10, 1% of NEt3) as a red solid (193
mg, 49%); mp 70–75 °C; Rf = 0.18 (PE/EtOAc 10:1).
By following the general procedure B, using 3,4-methylenedioxycin-
namic acid (138 mg), (±)-18 was obtained after column chromatogra-
phy (PE/EtOAc 90:10, 1% of NEt3) as an orange solid (267 mg, 88%);
mp 153–155 °C; Rf = 0.22 (PE/EtOAc 90:10).
IR (film): 2965, 1737, 1627, 1464, 1431, 1319, 1241, 1211, 1134,
IR (film): 2967, 1730, 1628, 1601, 1500, 1490, 1464, 1447, 1430,
1367, 1317, 1299, 1247, 1136, 1119, 1100, 1032, 1006, 926, 817,
1085, 1017, 814, 720 cm–1
.
751 cm–1
.
1H NMR (300 MHz, CDCl3):  = 8.18 (s, 2 H, 2 × ArCH), 8.17 (s, 2 H, 2 ×
ArCH), 4.69 (dd, J = 1.4, 2.4 Hz, 2 H, 2 × FcCH), 4.40 (s, 10 H, 2 × Cp),
4.15 (dd, J = 1.2, 2.4 Hz, 2 H, 2 × FcCH), 4.09 (br s, 2 H, 2 × CH), 4.03 (t,
J = 2.6 Hz, 2 H, 2 × FcCH), 3.39 (br s, 2 H, 2 × CH), 1.47 (br s, 6 H, 2 ×
CH3), 1.41 (br s, 6 H, 2 × CH3), 1.06 (br s, 6 H, 2 × CH3), 1.02 (br s, 6 H,
2 × CH3).
13C NMR (75.4 MHz, CDCl3):  = 165.6 (2 × C=Oamide), 164.3 (C=Oester),
164.2 (C=Oester), 133.7 (2 × ArC), 130.0 (4 × ArCH), 115.0 (FcC–O),
114.9 (FcC–O), 79.9 (2 × FcC), 71.3 (2 × Cp), 62.8 (FcCH), 62.7 (FcCH),
62.0 (2 × FcCH), 60.8 (FcCH), 60.7 (FcCH), 55.5 (CH), 50.5 (CH), 45.9
(2 × CH), 20.7 (8 × CH3).
1H NMR (300 MHz, CDCl3):  = 7.64 (d, J = 15.9 Hz, 1 H, CH=CH=CO),
7.04 (d, J = 1.7 Hz, 1 H, ArCH), 7.01 (dd, J = 1.7, 7.9 Hz, 1 H, ArCH), 6.80
(d, J = 7.9 Hz, 1 H, ArCH), 6.34 (d, J = 15.9 Hz, 1 H, CH=CH=CO), 6.00 (s,
2 H, CH2), 4.56 (dd, J = 1.4, 2.4 Hz, 1 H, FcCH), 4.37 (s, 5 H, Cp), 4.11
(dd, J = 1.5, 2.6 Hz, 1 H, FcCH), 4.05 (br s, 1 H, CH), 3.98 (t, J = 2.6 Hz, 1
H, FcCH), 3.37 (br s, 1 H, CH), 1.45 (br s, 6 H, 2 × CH3), 1.04 (br s, 6 H,
2 × CH3).
13C NMR (75.4 MHz, CDCl3):  = 165.9 (C=O), 165.8 (C=O), 150.1 (ArC–
O), 148.6 (ArC–O), 145.9 (CH=CH=CO), 128.9 (ArC), 125.0 (ArCH),
115.3 (CH=CH=CO), 114.8 (FcC–CO), 108.8 (ArCH), 106.8 (ArCH), 101.8
(CH2), 80.0 (FcC), 71.4 (Cp), 63.0 (FcCH), 62.0 (FcCH), 61.1 (FcCH), 50.7
(CH), 46.1 (CH), 21.0 (4 × CH3).
(±)-N,N-Diisopropyl-2-(ferrocenoyl)ferrocenecarboxamide [(±)-
16]
(±)-N,N-Diisopropyl-2-(piperoyl)ferrocenecarboxamide [(±)-19]
By following the general procedure B, using ferrocenecarboxylic acid
(165 mg), (±)-16 was obtained after column chromatography (PE/EtOAc
90:10, 1% of NEt3) as an orange solid (277 mg, 85%); mp 58–62 °C; Rf =
0.26 (PE/EtOAc 10:1).
By following the general procedure B, using piperic acid (157 mg), (±)-
19 was obtained after column chromatography (PE/EtOAc 90:10 to
80:20, 1% of NEt3) as an orange solid (291 mg, 92%); mp 59–64 °C; Rf =
0.23 (PE/EtOAc 90:10).
© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I

I
W. Erb et al.
PSP
Synthesis
IR (film): 2965, 1722, 162, 1605, 1489, 1446, 1433, 1368, 1320, 1521,
1227, 1203, 1108, 1036, 997, 928, 814, 754 cm–1
(4) Alba, A.-N. R.; Rios, R. Molecules 2009, 14, 4747.
.
(5) (a) Zhu, D.-Y.; Chen, P.; Xia, J.-B. ChemCatChem 2016, 8, 68.
(b) Gao, D.-W.; Gu, Q.; Zheng, C.; You, S.-L. Acc. Chem. Res. 2017,
50, 351. (c) Schmiel, D.; Butenschön, H. Organometallics 2017,
36, 4979. (d) Kong, W.-J.; Shao, Q.; Li, M.-H.; Zhou, Z.-L.; Xu, H.;
Dai, H.-X.; Yu, J.-Q. Organometallics 2018, 37, 2832.
(6) (a) Aratani, T.; Gonda, T.; Nozaki, H. Tetrahedron Lett. 1969,
2265. (b) Aratani, T.; Gonda, T.; Nozaki, H. Tetrahedron 1970, 26,
5453. (c) Price, D.; Simpkins, N. S. Tetrahedron Lett. 1995, 36,
6135. (d) Nishibayashi, Y.; Arikawa, Y.; Ohe, K.; Uemura, S. J.
Org. Chem. 1996, 61, 1172.
(7) Tsukazaki, M.; Tinkl, M.; Roglans, A.; Chapell, B. J.; Taylor, N. J.;
Snieckus, V. J. Am. Chem. Soc. 1996, 118, 685.
(8) Firth, J. D.; Canipa, S. J.; Ferris, L.; O’Brien, P. Angew. Chem. Int.
Ed. 2018, 57, 223.
(9) Genet, C.; Canipa, S. J.; O’Brien, P.; Taylor, S. J. Am. Chem. Soc.
2006, 128, 9336.
(10) Touafek, O.; Kabouche, A.; Kabouche, Z. J. Chem. Res. 2000, 499.
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Wang, C.; Miyamoto, K.; Saito, T.; Takita, R.; Uchiyama, M. J. Am.
Chem. Soc. 2016, 138, 9166.
1H NMR (300 MHz, CDCl3):  = 7.48 (dd, J = 10.7, 15.2 Hz, 1 H,
CH=CH=CH=CH=CO), 6.99 (d, J = 1.6 Hz, 1 H, ArCH), 6.92 (dd, J = 1.6,
8.1 Hz, 1 H, ArCH), 6.84 (d, J = 15.5 Hz, 1 H, CH=CH=CH=CH=CO), 6.78
(d, J = 8.1 Hz, 1 H, ArCH), 6.71 (dd, J = 10.7, 15.5 Hz, 1 H,
CH=CH=CH=CH=CO), 6.01 (d, J = 15.2 Hz, 1 H, CH=CH=CH=CH=CO),
5.98 (s, 2 H, CH2), 4.56 (dd, J = 1.5, 2.5 Hz, 1 H, FcCH), 4.37 (s, 5 H, Cp),
4.11 (dd, J = 1.5, 2.5 Hz, 1 H, FcCH), 4.04 (br s, 1 H, CH), 3.97 (t, J = 2.56
Hz, 1 H, FcCH), 3.38 (br s, 1 H, CH), 1.46 (br s, 6 H, 2 × CH3), 1.04 (br s,
6 H, 2 × CH3).
13C NMR (75.4 MHz, CDCl3):  = 165.9 (C=Oester), 165.7 (C=Oamide),
148.9 (ArC–O), 148.5 (ArC–O), 146.4 (CH=CH=CH=CH=CO), 141.3
(CH=CH=CH=CH=CO), 130.7 (ArC), 124.6 (CH=CH=CH=CH=CO), 123.4
(CH=CH=CH=CH=CO), 114.6 (FcC–CO), 108.8 (ArCH), 106.2 (ArCH),
101.6 (CH2), 80.2 (FcC), 71.4 (Cp), 63.1 (FcCH), 62.1 (FcCH), 61.0
(FcCH), 50.7 (CH), 46.0 (CH), 20.9 (4 × CH3).
Funding Information
(12) Dayaker, G.; Tilly, D.; Chevallier, F.; Hilmersson, G.; Gros, P. C.;
Mongin, F. Eur. J. Org. Chem. 2012, 6051.
This work was supported by the Université de Rennes 1 and CNRS.()
(13) Tazi, M.; Erb, W.; Halauko, Y. S.; Ivashkevich, O. A.; Matulis, V. E.;
Roisnel, T.; Dorcet, V.; Mongin, F. Organometallics 2017, 36,
4770.
Acknowledgment
(14) Sanders, R.; Mueller-Westerhoff, U. T. J. Organomet. Chem. 1996,
512, 219.
(15) Brikci-Nigassa, N. M.; Bentabed-Ababsa, G.; Erb, W.; Mongin, F.
Synthesis 2018, 50, 3615.
(16) Dearden, M. J.; Firkin, C. R.; Hermet, J.-P. R.; OʼBrien, P. J. Am.
Chem. Soc. 2002, 124, 11870.
We gratefully acknowledge the Fonds Européen de Développement
Régional (FEDER; D8 VENTURE Bruker AXS diffractometer) and Ther-
mofisher (generous gift of 2,2,6,6-tetramethylpiperidine). W.E. would
like to thank Prof. F. Mongin for support, critically reviewing this doc-
ument, and making valuable suggestions.
(17) (a) Schlosser, M. Angew. Chem. Int. Ed. 2005, 44, 376.
(b) Schnurch, M.; Spina, M.; Khan, A. F.; Mihovilovic, M. D.;
Stanetty, P. Chem. Soc. Rev. 2007, 36, 1046. (c) Schnürch, M.
Recent Progress on the Halogen Dance Reaction on Heterocycles,
In Halogenated Heterocycles: Synthesis, Application and Environ-
ment; Iskra, J., Ed.; Springer: Berlin, 2012, 185. (d) Yamane, Y.;
Sunahara, K.; Okano, K.; Mori, A. Org. Lett. 2018, 20, 1688.
(e) Erb, W.; Mongin, F. Tetrahedron 2016, 72, 4973. (f) Tazi, M.;
Hedidi, M.; Erb, W.; Halauko, Y. S.; Ivashkevich, O. A.; Matulis, V.
E.; Roisnel, T.; Dorcet, V.; Bentabed-Ababsa, G.; Mongin, F.
Organometallics 2018, 37, 2207.
(18) Bhakuni, B. S.; Yadav, A.; Kumar, S.; Patel, S.; Sharma, S.; Kumar,
S. J. Org. Chem. 2014, 79, 2944.
(19) Anderson, J. C.; Blake, A. J.; Arnall-Culliford, J. C. Org. Biomol.
Chem. 2003, 1, 3586.
(20) (a) Barder, T. E.; Walker, S. D.; Martinelli, J. R.; Buchwald, S. L.
J. Am. Chem. Soc. 2005, 127, 4685. (b) Chen, W.-B.; Xing, C.-H.;
Dong, J.; Hu, Q.-S. Adv. Synth. Catal. 2016, 358, 2072.
(21) Erb, W.; Hurvois, J.-P.; Roisnel, T.; Dorcet, V. Organometallics
2018, 37, 3780.
Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0039-1689917.
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References
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© 2019. Thieme. All rights reserved. — Synthesis 2019, 51, A–I