Stoichiometric reductive C-N bond formation of arylgold(III) complexes with N-nucleophiles

Article abstract of DOI:10.1002/adsc.201000598

The reductive formation of substituted anilines from amines and three well-defined aryl- gold(III) complexes, i.e., dichloro(2,6-lutidine)phen- ylgold(III) (2), dichloro(2,6-lutidine)-p-tolylgold(III) (3), and chlorobis(triphenylphosphine)phenylgold(III) chloride (4) was studied. The reaction is stoichiometric in gold and represents a key step of a potential gold-catalyzed intermolecular amination reaction of arenes. It proceeds smoothly with a broad range of N-nucleophiles in the presence of sodium acetate (NaOAc) and enables the selective formation of N-substituted anilines in good yields. A mechanistic pathway is proposed and discussed as well. Copyright

Full text of DOI:10.1002/adsc.201000598

FULL PAPERS
DOI: 10.1002/adsc.201000598
ꢀ
Stoichiometric Reductive C N Bond Formation of Arylgold(III)
N
Complexes with N-Nucleophiles
a
a
a
a
ˇ
´
Sꢀverine Lavy, Jeremie J. Miller, Marek Pazicky, Anne-Sophie Rodrigues,
Frank Rominger,b Christoph Jꢁkel,a Daniel Serra,a Nikolai Vinokurov,a
and Michael Limbacha,c,*
a
CaRLa – Catalysis Research Laboratory, Im Neuenheimer Feld 584, 69120 Heidelberg, Germany
Ruprecht-Karls-Universitꢁt, Organisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
BASF SE, GCB/C – M313, 67056 Ludwigshafen, Germany
b
c
Fax : (+49)-621-6066-48957; phone: (+49)-621-60-48957; e-mail: michael.limbach@basf.com
Received: July 27, 2010; Published online: November 17, 2010
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.201000598.
Abstract: The reductive formation of substituted ani- tion of arenes. It proceeds smoothly with a broad
lines from amines and three well-defined aryl- range of N-nucleophiles in the presence of sodium
gold
ylgold
(3), and chlorobis(triphenylphosphine)phenylgold- tic pathway is proposed and discussed as well.
(III) chloride (4) was studied. The reaction is stoi-
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
ꢀ
chiometric in gold and represents a key step of a po- Keywords: amination; C H activation; gold; homo-
tential gold-catalyzed intermolecular amination reac- geneous catalysis; reaction mechanisms
Introduction
which requires prefunctionalized haloarenes or phe-
nols.
In recent years gold-catalyzed transformations have
substantially increased in scope and utility.[1] How-
ACHTUNGTRENNUNG
(III)[2] (Scheme 1, step ꢁ) drags behind that
4
of the isoelectronic redox-couple Pt(II)/Pt(IV) and
more over Pd(II)/Pd(0). On the other hand, the aura-
tion of simple arenes with AuACTHUNTGRNEUNG(III) and Au(I) com-
plexes (Scheme 1, step ꢁ) occurs under much milder
1
conditions than the corresponding platination or pal-
ladination.[3,4]
As early as in 1931 Kharasch et al. reported on the
room temperature auration of unfuntionalized arenes
such as benzene with [AuCl3]2 to form [PhAuCl2]2 (1-
H).[5] This dimer is thermally labile and decomposes
readily to chlorobenzene and AuCl.[6]
We took Kharashꢂs finding as a stoichiometric
ꢀ
model for the C H activation in a potentially Au-cat-
alyzed intermolecular amination of unfunctionalized
arenes (Scheme 1). Such a transformation would
enable the one-step synthesis of anilines from arenes
and amines and could expand upon the scope of the
palladium-catalyzed Hartwig–Buchwald amination,[7]
Scheme 1. Hypothetical catalytic cycle for the Au-catalyzed
direct amination of benzene.
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Sꢀverine Lavy et al.
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The adducts of Kharashꢂs dimer 1-R with ligands L based on early reports of Parkin et al.,[12] but yielded
such as 2,6-lutidine are stable. Such a ligand-stabilized chlorobis(triphenylphosphine)phenylgold(III) chlo-
AHCTUNGTRENNUNG
monomer of the type ArAuCl2L (2-R) has first been ride (4) in maximally 26% yield, which results from
reported by Fuchita et al.[8] They were also the first two-fold attack of PPh3 on 1-H.
ones to report on a stoichiometric coupling of arenes
Crystals of complexes 2 and 4 suitable for X-ray
and acetylenes based on 2-R, which is a transforma- diffraction were grown from dichloromethane and the
tion complementary to the Sonogashira reaction, conformation of 2 was confirmed to be trans-di-
ACTHNUTRGNEUNG
albeit not catalytic in metal.[8] Fuchitaꢂs mechanistic chloro(2,6-lutidine)phenylgold(III) (see Figure 1).[13]
considerations remain elusive but point to the fact
that ligand exchange and reductive elimination took square planar or even an elongated square pyramidal
place (Scheme 1, steps ꢁ and ꢁ). geometry, depending on how the second chloride
The cationic complex 4 displays a slightly distorted
2
3
The reductive elimination from AuACTHNUTRGENN(UG III) complexes atom is treated (see Figure 2, Table 1). The goldACHTUNGTRENNUNG(III)
is known,[9,10] but to the best of our knowledge there center bears two triphenylphosphine ligands posi-
ꢀ
are only a few reports on the direct intermolecular re- tioned trans to each other with similar P Au bond dis-
action of arenes and N-nucleophiles.[11] Thus, a thor- tances (P1 Au1 =2.37 ꢄ and P2 Au1 =2.36 ꢄ). In
ꢀ
ꢀ
ꢀ
ough study of reductive C N bond formation with contrast to Fuchitaꢂs lutidine complex 2, the s-coordi-
Fuchitaꢂs phenyllutidine Au
(III) complex (2) and sur- nated phenyl ring in 4 is located trans to the basal
rogates would serve as an excellent model to under- chloride and cis to the two bulky phosphine ligands
ꢀ
ꢀ
ꢀ
stand the elementary steps involved in this transfor- (C2 C1 Au1 P1=87.248). The length of the carbon-
mation.
gold bond in 4 is with 2.05 ꢄ slightly elongated com-
pared to 2.02 ꢄ for 2. The second chloride is weakly
bound to the gold atom and is positioned at the apical
position of an elongated square-pyramid. The
Results and Discussion
Synthesis and Structural Characterization of
ArylgoldACHTUNGTRENNUNG(III) Complexes 2 and 4
The reaction of benzene (R=H) or toluene (R=Me)
with [AuCl3]2 in hexane is heterogeneous and pro-
ceeds smoothly to give regiospecifically, within
30 min, Kharashꢂs intermediates 1-R, which decom-
pose rapidly in solution and in the solid state. There-
fore, 1 was trapped with 2,6-lutidine without isolation
as reported by Fuchita et al.[8] to give the stabilized
arylgoldACHTUNGTRENNUNG(III) complex 2 in 29% (R=H) and 3 in 11%
yield (R=Me), respectively (Scheme 2). Although
the obtained yields are fairly low, it has to be consid-
ered that the maximum yield in this reaction is 50%,
as liberated HCl consumes [AuCl3]2 to give tetrachlor-
oauric acid. Surprisingly, the reaction of 1-H with
Figure 1. Molecular structure of 2 with thermal ellipsoids
drawn at 50% probability. Hydrogen atoms have been omit-
ꢀ
ted for clarity. Selected bond lengths (ꢄ): Au1 C5 2.017(6),
Au1 N1 2.173(5), Au1 Cl1 2.276(1). Selected bond angles
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
(8): N1 Au1 C5 180.0, Cl1 Au1 Cl1’ 177.85(5), N1 Au1
ꢀ
ꢀ
PPh3 did not give PhAuCl2PPh3 as was expected Cl1 91.08(3), C5 Au1 Cl1 88.92(3).
ꢀ
Scheme 2. Synthesis of arylgold
N
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ꢀ
Stoichiometric Reductive C N Bond Formation of ArylgoldACTHNUTRGNEU(GN III) Complexes with N-Nucleophiles
it for 24 h (0.01M in THF, 708C) ca. 80% of the start-
ing material was reisolated. The same is true for 3,
which did not show significant signs of decomposition
by NMR in the presence of aniline (pKb =9.42), even
after 5 d at room temperature in C6D6. Interestingly,
when the same experiment was repeated with diethyl-
amine as nucleophile (pKb =3.07), 3 decomposed
readily at room temperature within 2 h to give 4-
chlorotoluene in 92% yield. Such a P-ligand-induced
cis-elimination has been reported by Fuchita et al.
and others[14] for various cyclometallated Au
plexes.
ACHTUNGTRENN(UNG III) com-
When PPh3 (pKb =11.27) was added to a solution
of 3 in C6D6, chlorobenzene was isolated even after
5 min and in 95% yield. In this case, the reaction re-
sults in the clean formation of a by-product, which
shows a diagnostic 31P NMR signal at 45.9 ppm. This
is close but not identical to the 31P NMR signal of
PPh3AuCl (d=46.7 ppm) as upon addition of com-
mercially available PPh3AuCl to the NMR sample an
additional 31P signal evolved.
Figure 2. Molecular structure of 4 with thermal ellipsoids
drawn at 30% probability. Hydrogen atoms have been omit-
ꢀ
ted for clarity. Selected bond lengths (ꢄ): Au1 P1 2.366(2),
Au1 P2 2.361(2), Au1 C1 2.054(7), Au1 Cl1 2.383(2),
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Au1 Cl2 2.940(2). Selected bond angles (8): P1 Au1 P2
174.03(6), C1 Au1 Cl1 166.1(2), C1 Au1 P1 86.5(2), C1
Au1 P2 88.0(2), Cl1 Au1 P1 93.63(7), C1 Au1 P2
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
As acetate-containing AuACTHNUGTRNEUNG(III) complexes are
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
known to form goldACTHNUTRGNEU(GN III) amides from aromatic
91.12(7). Selected torsion angle (8): C2 C1 Au1 P1 87.2(6).
amines,[15] we tried various acetate sources to enable a
potential chlorine to acetate ligand exchange in situ.
Au1 Cl2 bond length is 2.94 ꢄ, below the sum of the Indeed, addition of ammonium acetate to 2 and di-
ꢀ
van-der-Waals radii (3.5 ꢄ).
benzylamine yielded dibenzylphenylamine (5b), albeit
in low yield (3%, Scheme 3, Table 2).
A change of the counterion from Cu2+ (41%) over
Ag+ (66%) to Me4N+ (78%) increased the yield in 5b
significantly. Although the fastest exchange from
chloride to acetate was expected for AgOAc, finally,
ꢀ
Reductive C N Bond Formation by Reaction of
Nucleophiles with Arylgold
A
In the absence of nucleophile and base the Fujita NaOAc turned out to be the optimal base giving 5b in
complex 2 is remarkably stable. Even after refluxing 88% yield. In turn, the yield in 5b drastically decreas-
Table 1. Crystallographic data for 2, 4 and 6.
Compound
2
4
6
Emp. formula
M [gmolꢀ1]
T [K]
C13H14AuCl2N
452.12
200
C42H35AuCl2P2·1.5CH2Cl2
996.90
200
C10H14AuCl2NO
432.09
200
Crystal system
Space group
a [ꢄ]
b [ꢄ]
c [ꢄ]
monoclinic
C2/c
7.9966(3)
15.1581(5)
11.6109(4)
90
monoclinic
P21/c
9.7810(1)
18.0733(1)
26.8809(3)
90
monoclinic
P21/c
8.3597(17)
17.577(4)
8.5170(17)
90
a (8)
b (8)
94.7910(10)
90
1402.48(9)
4
10.85
6961
1610/0.0529
81/0
0.0226/0.0551/1.020
99.242(1)
90
4690.18(8)
4
3.52
38464
7997/0.0659
506/60
0.043/0.124/1.17
108.417(4)
90
1187.3(4)
4
12.81
12392
2954/0.0207
136/0
0.015/0.037/1.05
g (8)
V [ꢄ3]
Z
m [mmꢀ1]
Refl. tot.
Refl. unique/Rint
Parameters/restraints
R[a]/Rw[b]/GOF
[a]
R1=SjjFo jꢀjFc jj/SjFo j for all I>2s(I).
[b]
2
2
Rw =[Sw
U
(Fo )2]1/2 for all I>2s(I).
ACHTUNGTRENNUNG
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Sꢀverine Lavy et al.
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Scheme 3. Effect of base on the reaction of 2 with an N-nu-
cleophile. For details, see Table 2.
ꢀ
Scheme 4. Scope of C N bond formation with complexes 2
and 5. For details, see Table 3.
Table 2. Effect of base, solvent, temperature and time on Table 3). The reaction was broadly applicable and
the reaction of 2 with an N-nucleophile.
works with anilines to give 5a, d, e, basic dialkyl-
AHCTUNGTREGaNNUN mines to give 5b, c, f, sulfonamides to give 5g, h and
even with amides to give 5i, j.
The yields obtained with complex 2 are similar or
significantly higher if compared to 4 under otherwise
identical conditions, as shown for the reaction with
morpholine (59 vs. 99% yield), dibenzylamine (53 vs.
88%) and aniline (97 vs. 81%).
Additive
R1, R2 Solvent Temp. Time Yield 5a, b
[8C]
[h]
[%][c]
None[a]
Bn, Bn THF
Bn, Bn THF
70
70
70
70
70
70
70
70
70
70
20
20
20
20
24
24
24
24
24
24
24
24
24
3
50
19
1.5
72
72
72
–
3
[d]
NH4OAc[a]
Me4NOAc[a] Bn, Bn THF
78
41
66
41
45
84
88
28[e]
99
91
60
58
70
85
[a]
NaO2CCF3
Bn, Bn THF
Bn, Bn THF
Bn, Bn THF
Bn, Bn THF
Bn, Bn THF
Bn, Bn THF
Bn, Bn THF
AgOAc[a]
[a]
CuACHTUNGTRENNUNG(OAc)2
[a]
Cs2CO3
[a]
Mechanistic Studies for Complex 2
K2CO3
NaOAc[a]
NaOAc[a]
NaOAc[b]
NaOAc[b]
NaOAc[b]
NaOAc[b]
NaOAc[b]
NaOAc[b]
Based on literature precedents a chlorine to acetate
exchange at the Au center as a first step into the re-
ductive elimination is suggested[15] and this exchange
has indeed been observed for acetate, and other nu-
cleophiles such as methoxide and hydroxide.[4,9a] De-
spite this, we believe that the first mechanistic step
(cf. Scheme 1, Scheme 5) is a ligand exchange from
2,6-lutidine to the N-nucleophile, as: a) upon addition
H, Ph
H, Ph
H, Ph
H, Ph
H, Ph
H, Ph
THF
THF
THF
C6H6
CH2Cl2 20
MeCN 20
[a]
2 (30 mg), additive (5 equiv.) and Bn2NH (4 equiv.) in a
stock solution of THF (6 mL, 10 mg of n-decane) in a of NaOAc as base but without nucleophile under oth-
sealed mininertTM vial.
As above but 2 equiv. of aniline.
1
erwise identical conditions via H NMR there are no
[b]
[c]
[d]
[e]
signals assignable to acetate coordinated to gold,
which are expected at d=~2.6;[15] b) traces of free lu-
GC yield calculated with n-decane as internal standard.
Formation of biphenyl and chlorobenzene.
2 equiv. of Bn2NH.
tidine were detected by NMR; c) upon addition of
PPh3 as a strong s-donating ligand, 2 (0.03M in THF)
was quantitatively converted within 1 h to a new com-
plex (31P NMR: signal shifted from d=ꢀ5.3 to
~33.7 ppm) even at room temperature and free luti-
1
es upon reduction of the amount of nucleophile dine was liberated as observed by H NMR; d) this
(28%), as well as on changing the basicity of the single new species is supposed to be PhAuCl2PPh3
anion, as seen for the less basic trifluoroacetate coun- (1H NMR: two sets of aromatic signals in the ratio of
terion (41%). Interestingly, inorganic bases such as 3:1), e) upon addition of 1 equivalent of morpholine
Cs2CO3 (45%) and especially K2CO3 gave 5b in yields to 2 at room temperature, in the absence or in the
that are comparable to those obtained with NaOAc presence of NaOAc (after 1.5 h) all the starting com-
(84 vs. 88%).
plex was consumed and free lutidine and a new spe-
In non-polar solvents such as benzene the reaction cies formed which precipitated as colourless crystals
of 2 with aniline is slow and gives diphenylamine (5a) from the reaction mixture. The precipitate turned out
in 58% yield. More polar solvents such as dichloro- to be 6 by X-ray diffraction (Figure 3, Table 1).
ꢀ
ꢀ
methane and acetonitrile lead to better yields of 70
and 85%, respectively. Especially in THF the reaction 2 do not change significantly [Au C: 2.020(2) vs. 2.02,
The lengths of the Au C and Au N bonds in 6 and
ꢀ
ꢀ
ꢀ
proceeds rapidly to give 5a in a virtually quantitative Au N: 2.1734(19) vs. 2.17, Au Cl 2.2845(6) vs.
yield of 99%. Even after 19 (1.5 h) 5a is obtained in 2.27 ꢄ]. The change in bond angles is more signifi-
ꢀ
ꢀ
91 (60%) yield, respectively.
cant, i.e., with a glance at the N Au C angle, the Au
The scope of the reaction was subsequently evaluat- atom in 6 significantly deviates from a linear arrange-
ed using various amines under optimal reaction condi- ment [175.81(8) vs. 180.08]. The 1H NMR of 6 in
tions, i.e., 2, THF, 708C, NaOAc, 24 h (Scheme 4, THF-d8 showed a broad singlet at 4.47, which we
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ꢀ
Stoichiometric Reductive C N Bond Formation of Arylgold
N
ꢀ
Table 3. Scope of C N bond formation with complexes 2
and 5.
Entry RNH
Amine 5a–j
Yield of 5a–j
[%][a,b]
a
81 (97)[c]
Figure 3. Molecular structure of 6 with thermal ellipsoids
drawn at 30% probability. Hydrogen atoms have been omit-
b
c
88 (53)
99 (59)
ꢀ
ted for clarity. Selected bond lengths (ꢄ): Au1 C11
2.020(2), Au1 N21 2.173 (2), Au1 Cl1 2.2845(6). Selected
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
bond angles (8): N21 Au1 C11 175.81(8), Cl1 Au1 C11
ꢀ
ꢀ
ꢀ
ꢀ
90.07(7), Cl1 Au1 N21 86.75(6), Cl2 Au1 C11 88.89(7),
d
94
ꢀ
ꢀ
Cl2 Au1 N21 94.38(6).
assign to the NH proton, 5 aromatic protons with d=
6.96–7.08 ppm, and interestingly four diastereotopic
methylene groups originating from morpholine
(broad doublets at d=3.08, 3.34, 3.67 and 3.87 ppm,
cf. Supporting Information).
e
f
85
53
The coordination of aniline to the Au
6 leads to a strong acidification of the NH proton,[16]
and there is precedence that the formed Au(III)-
amido complexes are easily generated in the presence
of a mild base.[17] So is amidophenylgold
(III) complex
6 subsequently deprotonated by NaOAc to give the
putative T-shaped trigonal cationic species 7, where
amine and arene have the cis-conformation which is a
prerequesite for reductive elimination.[9a,18] Thus, cou-
pling product and the corresponding but not observed
Au(I) species 8 are formed (Scheme 5).
ACHTUNGTREN(NUNG III) center in
g
83
ACHTUNGTRENNUNG
h
i
69
91
42
AHCTUNGTRENNUNG
j
As a final proof for the initial ligand exchange hy-
pothesis, we chose the NHC complex SIMesAuCl2Ph
(9),[19] which is not as easily liberated from 2 as is luti-
dine. Indeed, the reaction of 9 under standard reac-
tion conditions gave only traces amounts of 5b (1%
yield), besides 53% of biphenyl and 15% of chloro-
benzene as identified by GC-MS (Scheme 6). This
finding supports the proposed mechanism.
[a]
2 (30 mg) and NaOAc (5 equiv.) in a stock solution of
nucleophile (4 equiv.) in THF (6 mL, 10 mg of n-decane)
in a sealed mininert vial.
GC yields calculated using n-decane as internal standard.
Numbers in brackets: 4 (5 mg) and NaOAc (5 equiv.) in
[b]
[c]
a
stock solution of nucleophile (2 equiv.) in THF
(1.5 mL, 10 mg of n-decane) in a sealed mininertTM vial
at 708C for 8 h.
ꢀ
Scheme 5. Proposed course of the Au
N
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Sꢀverine Lavy et al.
FULL PAPERS
Scheme 6. Attempted reductive amination with IMesAuCl2Ph and dibenzylamine.
Conclusions
ciprocal space. Structure solution and refinement were car-
ried out with the SHELXTL program system.[21] GC analy-
ses were carried out on a Agilent 6890N modular GC base
equipped with a split-mode capillary injection system and
flame ionization detector using a standard HP-5 capillary
In conclusion, we have shown that the lutidine ligand
in well-defined arylgold
G
ꢀ
mild C H activation of benzene with gold
E
column (30 mꢅ0.32 mmꢅ0.25 mm; He flow: 2.0 mLminꢀ1
;
ride (2 and 4) is labile and easily exchanged to an N-
program: 508C (1 min), 208Cminꢀ1 to 2508C (10 min). The
response factor ratios were determined by calibrations
curves and the GC yields were calculated as reported (see
Supporting Information).[22] Silica (60 ꢄ, 63–200 mesh) for
column chromatography was purchased from Chemie
nucleophile in the presence of acetate. Subsequent
ꢀ
C N bond formation occurs readily with amines,
amides, sulfonamides, and even imides leading to ary-
lated products in good to excellent yields. There is no
indication that acetate acts as a ligand to gold. The Brunschwig. Elemental analyses and mass spectra (ESI+)
were obtained from the chemistry department of the Uni-
versity of Heidelberg.
mechanism of this amination is in accord with the
general expectations on reductive eliminations from
square planar d8-complexes and a key intermediate in
the mechanism has been characterized by X-ray crys-
tallography. The development of a catalytic reductive
General Procedure for the Synthesis of Arylgold
Complexes 2 and 3
ACHTUNGTRENNUNG(III)
amination based on the couple gold(I)/goldACHTNUTRGNE(NUG III) exist-
ꢀ
ꢀ
ing out of C H activation, C N bond formation as
presented here, and re-oxidation of Au(I) is the focus
of our current research.
A hexane solution (10 mL) of arene (73.84 mmol) was
added to a hexane suspension (20 mL) of [AuCl3]2 (1.12 g,
1.84 mmol) at room temperature. The initial red color of the
solution rapidly changed to brown-orange. The solution was
stirred for 30 min at room temperature and then diethyl
ether was added at once (10 mL). The resulting suspension
was filtered and the filtrate treated with a diethyl ether solu-
tion of 2,6-lutidine (393 mg, 3.29 mmol, 10 mL). The result-
ing yellow solution was stirred at room temperature for an
additional hour and then volatiles were removed under
vacuum. Purification of the residue via column chromatog-
raphy (benzene/hexane=2:3) yielded 2 and 3 as pale yellow
solids.
Experimental Section
All reactions were performed under an argon atmosphere
using standard Schlenk techniques. Diethyl ether was dried
by distillation from Na/Ph2CO. Hexane and dichlorome-
thane were dried with an MBraun solvent purification
system. Methanol, diethyl ether, acetonitrile, tetrahydrofur-
an, dimethyl sulfoxide, 1,4-dioxane, and chloroform were
purchased as anhydrous solvent purity. All solvents were sa-
turated with argon prior to use. All deuterated solvents for
NMR measurements were degassed via freeze-pump-thaw
cycles and stored over molecular sieves (4 ꢄ). Starting mate-
rials were purchased in reagent grade purity from Acros, Al-
drich, Fluka, or Strem and used without further purification
Dichloro(2,6-lutidine)phenylgoldACTHNUTRGNEUNG
(III) (2):[8] Rf =0.46
(toluene); yield: 242 mg (29%). Crystals for X-ray analysis
were obtained by slow evaporation of a dichloromethane so-
lution. 1H NMR (CDCl3): d=3.08 (s, 6H, CH3), 7.31–7.13
(m, 7H, lut-H+Ar-H), 7.75 (t, 1H, J=6.0 Hz, lut-H);
13C NMR (CDCl3): d=24.7, 124.6, 127.1, 129.3, 130.1, 131.9,
139.9, 157.2; HR-MS (FAB): m/z=452.0201, calcd. for
C13H15N35Cl2Au (M +H)+: 452.0247; m/z=454.0274, calcd.
for C13H15N35Cl37ClAu (M+H)+: 454.0218.
1
unless otherwise stated. H, 13C{1H} and 31P{1H} NMR spec-
tra were recorded at room temperature on a Bruker 250
spectrometer operating at 200, 50, and 81 MHz, respectively,
with chemical shifts (d, ppm) reported relative to the solvent
peaks (1H NMR, 13C NMR). Data for X-ray crystal structure
determination were obtained with a Bruker Smart CCD dif-
fractometer (2, 4) or a Bruker APEX diffractometer (6).
Frames corresponding to a sphere of data were collected
using 0.38 w scans: radiation, Mo Ka; l=0.71073 ꢄ. Intensi-
ties were corrected for Lorentz and polarization effects, and
an empirical absorption correction was applied using the
SADABS program[20] based on the Laue symmetry of the re-
Dichloro(2,6-lutidine)-p-tolylgold
(III)
(3):[8]
Yield:
1
95 mg (11%) as a colorless solid. H NMR (CDCl3): d=2.34
(s, 3H, CH3), 3.07 (s, 6H, lut-CH3), 6.98 (d, 2H, J=8.0 Hz,
Ar-H), 7.12 (d, 2H, J=8.0 Hz, Ar-H), 7.29 (d, 2H, J=
7.5 Hz, lut-H), 7.75 (t, 1H, J=7.5 Hz, lut-H); 13C NMR
(CDCl3): d=20.6, 24.7, 124.6, 128.2, 130.1, 131.4, 136.7,
139.9, 157.2; HR-MS (FAB): m/z=466.0366, calcd. for
C14H17N35Cl2Au (M +H)+: 466.0404; m/z=468.0338, calcd.
ACTHNUTRGNEUNG
for C14H17N35Cl37ClAu(M+H)+: 468.0374.
2998
asc.wiley-vch.de
ꢃ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2010, 352, 2993 – 3000

ꢀ
Stoichiometric Reductive C N Bond Formation of ArylgoldACTHNUTRGNEU(GN III) Complexes with N-Nucleophiles
Chlorobis(triphenylphosphine)phenylgold
(III) chloride
and discussion. S. L., J. J. M., M. P., A.-S. R., C. J., D. S., N.
V. and M. L. work at CaRLa, which is a joint project of
BASF SE and the University of Heidelberg, being co-fi-
nanced by the University of Heidelberg, the State of Baden-
Wꢀrttemberg and BASF SE. Support of these institutions is
greatly acknowledged.
(4): hexane solution (10 mL) of benzene (5.76 g,
A
73.84 mmol) was added to a hexane suspension (20 mL) of
[AuCl3]2 (1.00 g, 1.64 mmol) at room temperature. The ini-
tial red color of the solution rapidly changed to brown-
orange. The solution was stirred for 30 min at room temper-
ature and then diethyl ether was added at once (10 mL).
The resulting suspension was filtered and the solution treat-
ed with a diethyl ether solution of triphenylphosphine
(95 mg, 3.62 mmol, 10 mL). The resulting yellow solution
was stirred at room temperature for an additional hour and
volatiles were then removed under vacuum. Recrystalliza-
tion of the residue from dichloromethane/hexane, washing
with diethyl ether and drying under vacuum afforded 4 as a
colorless solid; yield: 0.39 g (26%). Crystals suitable for X-
ray analysis were grown by slow diffusion of diethyl ether
into a dichloromethane solution of 4 at 48C. 1H NMR
(CDCl3): d=6.51 (bs, 2H, Ph-H), 6.74 (t, 1H, J=7.5 Hz, Ph-
H), 7.03 (d, 2H, J=7.5 Hz, Ph-H), 7.3–7.9 (m, 30H, PPh3-
H); 13C NMR (CDCl3): d=125.6, 128.6, 129.9, 131.6, 134.8;
31P{1H} NMR (CDCl3): d=31.3; HR-MS (ESI): m/z=
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833.1547, calcd. for C42H35AuClP2ACTHUNGTRENNUNG
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General Procedure for the Reaction of 2 with Various
N-Nucleophiles to Yield 5a–j
To an oven-dried mininertTM vial were added 2 (30 mg,
67 mmol, 1 equiv.) and NaOAc (27 mg, 330 mmol, 5 equiv.).
In cases where the N-nucleophile was a solid, the N-nucleo-
phile was added to the mininertTM vial in solid form
(266 mmol, 4 equiv.). The flask was then sealed under argon,
and n-decane (10 mg) and THF (6 mL) were added to the
reaction mixture via syringe. In cases where the N-nucleo-
phile was a liquid, the N-nucleophile was added to the reac-
tion flask via syringe (266 mmol, 4 equiv.). The vial was
promptly placed in a 708C oil bath and stirred for 24 h. The
yield of 5a–j was determined by GC. For determination of
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Reaction to Afford 4-Phenylmorpholine (5c) on a
Preparative Scale
Under argon to an oven-dried Carius tube were added di-
chloro(2,6-lutidine)phenylgoldACTHUNTGRNEUNG(III) (2, 136 mg, 300 mmol),
NaOAc (123 mg, 1.5 mmol) and THF (27 mL). Morpholine
(105 mL, 1.2 mmol) was added to the reaction mixture via sy-
ringe. The vial was promptly placed in a pre-heated oil bath
(708C) and stirred for 24 h. After filtration of the reaction
mixture over celite and removal of volatiles under vacuum,
the crude reaction mixture was purified by flash chromatog-
raphy (pentane/diethyl ether=7:3) to afford 5c; yield: 45 mg
1
(92%); H NMR (CDCl3):): d=3.17 (t, J=4 Hz, 4H), 3.88 (t,
J=4 Hz, 4H), 6.91 (m, 3H), 7.30 (t, J=8 Hz, 2H).
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