Gold catalysis: Phenol synthesis in the presence of functional groups

Article abstract of DOI:10.1002/chem.200501268

The effect of different substituants, such as bromo, chloromethyl, hydroxymethyl, formyl, acetyl, carboxy, and acylated hydroxymethyl and ammonium groups, on the furan ring of substrates in gold-catalyzed phenol synthesis has been investigated. The furan

Full text of DOI:10.1002/chem.200501268

DOI: 10.1002/chem.200501268
Gold Catalysis: Phenol Synthesis in the Presence of Functional Groups
A. Stephen K. Hashmi,*[a] Jan P. Weyrauch,[a] Elzen Kurpejovic´,[a] Tanja M. Frost,[a]
Burkhard Miehlich,[a] Wolfgang Frey,[a, c] and Jan W. Bats[b, c]
Abstract: The effect of different sub-
stituents,such as bromo,chloromethyl,
hydroxymethyl,formyl,acetyl,carboxy,
and acylated hydroxymethyl and am-
monium groups,on the furan ring of
substrates in gold-catalyzed phenol
synthesis has been investigated. The
furan ring was also replaced by differ-
ent heterocycles,such as pyrroles,thio-
phenes,oxazoles,and a 24,-dimethoxy-
phenyl group; gold catalysis then deliv-
ered no phenols,but occasionally other
products were obtained. [Ru3(CO)12]
also catalyzed the conversion of 1 at a
Pauson–Khand reaction. Efforts to pre-
pare vinylidene complexes of 1 provid-
ed the only evidence for these species;
in the presence of a phosphane ligand
with ruthenium an interesting deoxyge-
nation to 22 was observed. The phenol
2c was converted to the allyl ether,a
building block for para-Claisen rear-
rangements,and to the aryl triflate,a
building block for cross-coupling reac-
tions.
low rate,[Os (CO)12] failed as a cata-
3
lyst,and with [Co 2(CO)8] the alkyne
complex 19 can be obtained,it does
not lead to any phenol but reacts with
norbornene to give the product of a
Keywords: arenes · gold · homoge-
neous catalysis
· Pauson–Khand
reaction · ruthenium
Introduction
The gold-catalyzed[1] synthesis of phenols 2 from furans 1
(Scheme 1) has attracted considerable attention. It is a
highly selective and very robust reaction,neither water nor
oxygen need to be excluded,and due to the absence of para-
magnetic species it can conveniently be monitored by NMR
spectroscopy.[2]
After our initial publication[2] in which we also described
that the furans 1 could potentially be generated in situ from
allenyl ketones 3 or propargyl ketones 4,Echavarren and
co-workers[3] discovered that platinum(ii) can also catalyze
the reaction of 1 to 2. They were able to reveal significant
´
[a] Prof. A. S. K. Hashmi,Dipl.-Chem. J. P. Weyrauch,Dr. E. Kurpejovic ,
Dipl.-Chem. T. M. Frost,Dr. B. Miehlich,Dr. W. Frey
Institut für Organische Chemie,Universität Stuttgart
Pfaffenwaldring 55,70569 Stuttgart (Germany)
Fax : (+49)711-685-4321
Scheme 1. Gold-catalyzed phenol synthesis.
E-mail: hashmi@hashmi.de
mechanistic details of this reaction by the observation of
side products and theoretical calculations; these mechanistic
insights subsequently led to spectacular developments in the
field of enyne cyclization reactions[4] (a 1,6-enyne is a sub-
structure of 1). Our group,at the same time as Echavarrenꢀs
group,observed that platinum( ii) catalyzes these reactions;
in addition we found that other d8 complexes,such as palla-
[b] Dr. J. W. Bats
Institut für Organische Chemie und Chemische Biologie
Johann Wolfgang Goethe-Universität Frankfurt am Main
Marie-Curie-Strasse 11,60439 Frankfurt (Germany)
[c] Dr. W. Frey,Dr. J. W. Bats
Contact for crystallographic investigation.
Supporting information for this article (experimental procedures and
data for 1k–1q, 1s–1u, 7–9, 11–13, 15, 17,and 18) is available on the
WWW under http://www.chemeurj.org/ or from the author.
[5]
dium(ii),iridium( i),and rhodium( i),are also active. Never-
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FULL PAPER
theless,the gold catalysts are by far the most active and
with gold,unlike in the platinum-catalyzed reactions,no sig-
nificant amounts of side products were observed.[6] Recently,
we proved experimentally that arene oxides are intermedi-
ates of the reaction.[7] In addition we investigated reactions
involving gold complexes with N- and N,O-ligands which al-
lowed the amount of catalyst used to be reduced to
0.07 mol% (1180 turnovers) and which also made possible
an efficient synthesis of benzo-anellated six-membered het-
erocycles[6] (in all but one of the then known examples a
tether of three atoms had been used; for a satisfactory con-
version of substrates with a tether of four atoms about
6 mol%[2] of AuCl3 instead of the usual 2 mol% were
needed). After investigating the applications of the synthesis
of furfuryl-substituted arenes and biaryl compounds,[8] a fur-
ther study of the methodology revealed that in principle a
gold-catalyzed tandem hydroarylation/cycloisomerization
process leading to the formation of five new bonds is possi-
ble,while the reaction of 1 to 2 leads to only four new
bonds.[9] The only example in natural product synthesis so
far is the total synthesis of the sesquiterpene Jungianol in
six steps without using a single protecting group.[10]
In most of the known examples apart from an N-sulfonyl
group,an oxygen atom,or a propargylic carbonyl group in
the tether no functional groups other than the reacting
alkyne and furan subunits were present (Table 1,entries 1–
9). The only exception is with substrate 1j (Table 1,
entry 10),for which the initially formed o-alkynylphenol iso-
merizes to the benzofuran 6 in a second gold-catalyzed
step.[5] The formation of the constitutional isomer 5 in addi-
tion to 2i (Table 1,entry 9) on the other hand shows that
the absence of a substituent R1 is also problematic.
of different functional groups at different positions. Herein
we present the results of our investigation.
Results and Discussion
Catalysis reactions: We started with the 2-bromofuran deriv-
ative 1k (Table 2) that is readily available from 5-bromofur-
fural. No conversion was observed. This is in accord with re-
lated results of Echavarren and co-workers[11] who also did
not observe a phenol with the analogous 5-bromofuryl prop-
argyl ether and PtCl2 as catalyst,but could optimize the re-
action conditions to obtain a side product.[12] Placing the
bromo substituent at a different position on the furan ring
(1l,Table 2,entry 2) delivered 2l,which immediately pre-
cipitated from the acetonitrile solution. Compound 2l is
only soluble in DMSO; purification by precipitation from
DMSO with H2O led to heavy losses of the product but de-
livered analytically pure material. Substrate 1m has a dime-
thylammonium group in the tether; with bromide as the
counteranion no conversion was observed (Table 2,entry 3).
We assumed that 20 equivalents of BrÀ with respect to the
catalyst simply blocked the coordination sites for the sub-
strate by competitive coordination. Use of the hexafluoro-
phosphate 1n proved this hypothesis (Table 2,entry 4); a
48% yield of the product 2n was obtained. Then 1o bearing
a chloromethyl substituent was tested. An 80% yield of 2o
was observed by NMR spectroscopy,but we did not succeed
in isolating the neat product; a reaction of the benzylic
chloride with nucleophilic groups (for example,the phenolic
hydroxy group) during the work up is probably responsible
for this. Most unfortunately the corresponding alcohol (1p,
Table 2,entry 6),aldehyde ( 1q,Table 2,entry 7),ketone
(1r,Table 2,entry 8),and carboxylate ( 1s,Table 2,entry 9)
did not react. In the case of 1p and 1q a gold mirror was ob-
served after a short time.[13] The reason for performing these
experiments was the low selectivity observed with substrates
with R1 =H (see 1i,Table 1,entry 9). If the conversion of
1q or 1s had been successful,a subsequent decarbonyla-
tion[14] or retro-Kolbe–Schmitt reaction[15] would have deliv-
ered 2i without 5 being produced as a side product. In the
case of a successful conversion of 1p, 2p could have been
oxidized to either 1q or 1s. Ketone 1r was tested in order
to see whether the reducing aldehyde group in 1q was re-
sponsible for the failure of the catalysis or whether the pres-
ence of an acceptor in general is a problem,which indeed
seems to be the case. Switching from the alcohol 1p to the
acetate 1t gave a satisfactory conversion,but as with the
chloride 1o,isolation of the product was a significant prob-
lem. Finally,the pivaloyl-protected 1u allowed isolation of
2u in a satisfactory yield (Table 2,entry 11).
For further synthetic applications it was important to
study the tolerance of this catalytic reaction to the presence
Table 1. Different substrates already tested in the cycloisomerization of
w-alkynylfurans 1 (R2 =H).
Entry Sub
A
R3
R4
X
Product
(Yield [%])
AHCTREUNG
1
2
3
4
5
6
7
8
9
1a
1b
1c
1d
1e
1 f
1g
1h
1i
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
H
H
H
CH3
H
H
H
H
H
H
H
H
H
CH2
O
NTs
NTs
2a (65)
2b (69)
2c (97)
2d (94)
2e (93)
2 f (96)
CH3 NTs
Next we discuss the effect of location of the carbonyl sub-
stituent on the furan ring and the variation of the heterocy-
cle in the starting material (Table 3). Instead of the furan
ring in 1 several other synthetically relevant heterocycles
were investigated.
H
H
H
H
H
NNs
C(CO2Me)2 2g (88)
A
N(Ts)CH2
NTs
NTs
2h (81)[a]
2i (31) + 5 (51)
2j (23) + 6 (48)
10
1j
C=CPr
H
[a] 6.0 mol% AuCl3.
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A. S. K. Hashmi et al.
Table 2. Different functionalized substrates 1 in gold-catalyzed phenol synthesis (R3 =R4 =H).
The ester 7 as well as the pyr-
Entry
Substrate
R1
R2
X
T [8C]
t [h]
Product
Yield [%][a]
role
8
gave no conversion
(Table 3,entries 1 and 2).
Switching to the N-tosyl-pyrrole
9 gave instead of the desired
aniline the anellated pyrrole 10
in good yield (Table 3,entry 3).
With furans and PtII catalysts
Echavarren and co-workers ob-
served similar reactions.[16] The
thiophene 11 (Table 3,entry 4)
was completely inactive,which
again is in accord with the ob-
servations of Echavarren and
co-workers[11] with PtII catalysts.
The oxazoles 12, 13,and 15
(Table 3,entries 5–7) would
have provided a nice route to 3-
hydroxy- or 4-hydroxypyridines,
but either no conversion occur-
red or propargyl alcohol was
eliminated to give the vinyloxa-
zoles 14 and 16. The dimethox-
ybenzyl derivative 17 under-
went a 50% conversion,but no
clean compound could be iso-
lated from the complex product
mixture. Compound 18 with the
side-chain attached to the 3-po-
sition of the furan ring did not
react at all.
1
2
3
4
5
6
7
8
1k
1l
Br
CH3
CH3
CH3
CH2Cl
CH2OH
CHO
Ac
CO2H
CH2OAc
CH2OPiv
H
Br
H
H
H
H
H
H
H
H
H
NTs
NTs
50
RT
50
24
24
24
26
72
24
24
24
24
24
72
–
2l
–
2n
2o
–
–
–
–
2t
2u
–
93 (36)
+
1m
1n
1o
1p
1q
1r
1s
1t
1u
NMe2 BrÀ
–
48
80 (–)
+
À
NMe2 PF6
50
NTs
NTs
O
NTs
O
RT
RT
RT
60
80
RT
RT
–
–
–
9
10
11
–
NTs
NNs
90 (6)
90 (62)
[a] Determined by NMR spectroscopy; yields of isolated products are given in parentheses.
Table 3. Gold-catalyzed reactions of other heterocycles with alkynyl groups in the side chain.
Entry
1
Substrate
Catalyst
AuCl3
T [8C]
t [h]
Product
–
Yield [%][a]
–
50
24
[b]
2
3
AuCl3
RT
RT
1
–
–
[c]
AuCl3
0.5
(77)
4
5
AuCl3
AuCl3
50
50
24
15
–
–
–
–
We also studied the effect of
catalyst on the reaction. First,
we used [Ru3(CO)12] as another
d8 system. For the conversion of
1c to 2c a yield of up to 66%
could be obtained (Table 4,en-
tries 1–4),but use of a noncoor-
dinating solvent such as chloro-
form or benzene was essential.
However,the reactions were
slower than with the gold cata-
lysts and the selectivity was also
lower. On the other hand,
[Os3(CO)12] did not provide 2c
in significant amounts under
any of the tested conditions
(Table 4,entries 5–9). Since the
creation of a free coordination
site in [Os3(CO)12] is much
6
7
Na
Na
G
50
50
15
15
51
67
8
9
AuCl3
AuCl3
RT
RT
24
–
–
–
–
168
[a] Determined by NMR spectroscopy; yields of isolated products are given in parentheses. [b] Rapid catalyst
deactivation occurred. [c] 10 mol% AuCl3.
Table 4. Reaction of 1c in the presence of [Ru3(CO)12] and [Os3(CO)12] as catalysts under different conditions.
Entry
Catalyst
[Ru3(CO)12]
[Ru3(CO)12]
[Ru3(CO)12]
[Ru3(CO)12]
[Os3(CO)12]
[Os3(CO)12]
[Os3(CO)12]
[Os3(CO)12]
[Os3(CO)12]
Mol%
Solvent
Additive
T [8C]
t [h]
Yield of 2c [%]
1
2
3
4
5
6
7
8
9
G
6.1
5.0
4.3
2.7
4.4
4.9
4.8
5.0
5.0
CD3CN
CDCl3
C6D6
[D6]acetone
CD3CN
CDCl3
C6D6
CD2Cl2
[D6]DMSO
–
–
–
–
50
50
50
50
50
50
50
35
120
21
11
11
10
5
10
10
21
5
–
64
66
–
–
–
–
–
G
more
difficult
than
in
E
[Ru3(CO)12],either Me NO had
3
E
to be added (Table 4,entries 5–
8)[17] or the reaction had to be
conducted at 1208C (Table 4,
entry 9).[18]
N
Me3NO
Me3NO
Me3NO
Me3NO/CD3CN
–
G
G
R
E
traces
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Gold-Catalyzed Phenol Synthesis
FULL PAPER
We then switched to another carbonyl complex,
[Co2(CO)8]. In stoichiometric reactions with 1c the (alky-
ne)hexacarbonyldicobalt complex 19 was isolated,which
was characterized by crystal-structure analysis (Scheme 2,
efforts to obtain stoichiometric [Ph3PAuI-alkynyl] com-
plexes[20] of 1c or vinylidene complexes 21 the known com-
pound 2c was isolated (Scheme 3). However a small amount
Scheme 3. Reaction of 1c with [CpRu(PPh3)2Cl].
A
Scheme 2. Reaction of 1c with [Co2(CO)8] and subsequent Pauson–
Khand reaction with norbornene.
of a material which could,according to 31P NMR and FAB
mass spectra,be 21 was also separated. This shows that not
only the d8 Ru0 system but also the d6 RuII are suitable pre-
catalysts.
Figure 1).[19] In the solid-state structure both the furan and
phenyl groups are approximately planar. Atom C11 deviates
0.100 Š from the furan plane,while the sulfur atom deviates
When starting with [Ru(methylallyl)
2(cod)] instead of
[CpRu
AHCTREUNG
vided evidence for a vinylidene species,in this case 23. A
small amount of a by-product was isolated and identified by
crystal-structure analysis as the deoxygenated arene 22
[19]
(Scheme 4,Figure 2).
Figure 1. Solid-state structure of 19.
0.086 Š from the phenyl plane. The alkyne group is coordi-
À
nated to two Co(CO)3 groups. The C9 C10 bond has a
length of 1.333(2) Š which corresponds to a C=C double
bond and therefore has been considerably lengthened by co-
ordination. This is also reflected in the H NMR spectrum;
Scheme 4. Reaction of 1c with [Ru(methylallyl)2(cod)].
A
1
the signal of the terminal alkyne position shifts from d=
2.06 ppm (t, J=2.4 Hz,1H) in 1c to d=5.96 ppm (s,1H) in
19. The C8-C9-C10 and C9-C10-H10 angles are 145.0(1) and
1428,respectively. Very similar dimensions have been found
in the crystal structures of other propynyl-bis(tricarbonylco-
balt) compounds listed in the Cambridge Structural Data-
base. The nitrogen atom shows only a small deviation from
planarity: the sum of the three valence angles about the ni-
trogen atom is 355.28. The shortest intramolecular contacts
are H2···O1 2.50 Š,H8A···O2 2.37 Š,and H11A···O1
Figure 2. Solid-state structure of 22.
We assume that the oxygen atom ends up at the phos-
phane moiety,probably transferred from the intermediate
arene oxide.[6] Examples of the deoxygenation of arene
oxides by phosphanes exist in the literature.[21]
À
2.46 Š. The crystal packing shows four intermolecular C
H···O interactions with H···O distances between 2.46 and
2.60 Š.
While no intramolecular reaction with the furan ring
could be induced by the cobalt carbonyl fragment, p-coordi-
nation of the alkyne and a subsequent intermolecular
Pauson–Khand reaction with norbornene proceeded readily
to give 20. This example shows that the preparation of p
complexes of the alkyne unit in 1c is possible. On the other
hand,alkynyl or vinylidene complexes were not formed. In
Finally,we looked at possible further derivatizations of 2.
After allylation to 24 (the crystal structure is shown in
Figure 3)[19] a thermal para-Claisen rearrangement to 25 was
possible (Scheme 5),providing a convenient route to further
substitution in the para-position of the pentasubstituted ben-
zene ring. The olefin group can be utilized in further steps.
The triflate 26 can also be formed (the solid-state structure
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A. S. K. Hashmi et al.
Figure 3. Solid-state structure of 24.
Scheme 6. Crystalline intermediates of the syntheses of substrates 1.
alkyne and heterocycle. A comparison of these structures
shows that there are two major families of conformers in the
solid state; only 1k has a significantly different conforma-
tion in the crystal.
In the first family, 1c, 1e, 1 f, 1i, 1j, 1l, 1t, 8, 9, 11,and
18,the relative orientations differ only slightly (Figure 5).
This is remarkable,especially since the side chains of these
substrates are quite different,which strongly suggests that
this conformation is an absolute minimum for these sulfona-
mide-tethered w-alkynylfurans.
Scheme 5. Further derivatization of 2c.
is shown in Figure 4)[19] and is also a useful group for further
cross-coupling or reduction reactions.
Figure 5. Superimposition of the amino moieties of compounds 1c, 1e,
1 f, 1i, 1j, 1l, 1t, 8, 9, 11, 18; two different views are shown.
Figure 4. Solid-state structure of 26.
In the second family, 1m, 1n,and 1s,there are also pro-
nounced similarities,even though they again possess differ-
ent side chains (Figure 6). Once more this suggests that this
conformation is an absolute minimum for the w-alkynylfur-
ans with an ether or ether-like dimethylammonium tether.
Structural studies and implications for reactivity: Several of
the substrates 1 and products 2 crystallized and crystal struc-
tures could be obtained.[19]
In addition crystal structures could also be obtained of
the compounds formed during the synthesis of the substrates
1 (see the Supporting Information). Tosylation of propargyl-
amine 27 delivered the N-propargyltosylamide 28,tosylation
of the fururylamines 29a and 29b gave the synthetic inter-
mediates 30a and 30b,and from the benzylamine 29c the
tosylamide 30c was obtained (Scheme 6).[19]
The crystal structures of the substrates 1c, 1e, 1 f, 1i, 1j,
1k, 1l, 1m, 1n, 1t, 8, 9, 11,and 18 were analyzed with re-
spect to the relative orientation of the reactive subunits,the
Figure 6. Superimposition of 1m, 1n,and 1s.
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Gold-Catalyzed Phenol Synthesis
FULL PAPER
In 1k the alkynyl group and the furan ring are very close;
they occupy a conformation which is ready for cyclization.
That the conformation of this sulfonamide differs from the
conformations of all the other sulfonamides shown in
Figure 5 might be due to packing effects.
Since these conformations were observed in the crystal-
line state,we investigated whether high steric barriers for
the interconversion of different conformers exist. We started
with 1s,the simplest starting material with only an oxygen
atom in the tether which has only a few unknown parame-
ters and for which also a crystal structure was available
(Figure 7),as the first model system. We used the MM3
reaction follows the path suggested by Echavarren and co-
workers[3] on the basis of the side-products and calculations
for the platinum-catalyzed case,it can be assumed that the
initial cyclopropanation (see also species C in reference [7])
of the enol-ether substructure of the furan is not electroni-
cally compatible with an acceptor substituent on the furan
ring. The failure of 1k to react can be explained similarly
since the bromo substituent also deactivates the p system.
Regarding the catalysis products,superposition of 2b, 2c,
2j, 22, 24,and 26 shows a high conformational similarity
(Figure 8). With the exception of 2c even the tosyl groups
have the same orientation with respect to the anellated
phenol.
Figure 7. Conformation of 1k in the crystal state.
[23]
force field[22] and the TINKER program
and initially op-
Figure 8. Superimposition of the products 2b, 2c, 2j, 22, 24,and 26.
timized the geometry of the crystal structure,which was re-
produced well. Then the dynamic behavior was investigated
in a molecular dynamics simulation (T=400 K; Dt=0.5 fs;
t=25 ps); this calculation showed that there are no torsional
barriers which cannot be passed under these conditions (an
mpg movie is included in the Supporting Information). We
then turned to 1k; we were faced with the problem that no
force-field parameters have been published for the sulfona-
mide moiety,so these parameters were generated by com-
parison with similar groups. A test of these new parameters
nicely reproduced the geometry obtained in the crystal
structure analysis. The subsequent molecular dynamics simu-
lation performed under the same conditions as mentioned
above for 1s also provided no evidence for barriers that
cannot be passed (another mpg movie is included in the
Supporting Information). The conformational changes are
In all the sulfonamides the nitrogen atom has a pyramidal
conformation,even in derivatives with only one carbon sub-
stituent and one hydrogen atom on the nitrogen. Typical de-
viations of the bond angles at the nitrogen atom from 3608
are 15.28 for 28,17.2 8 for 30a,15.2 8 for 30b,and 21.6 8 for
À
the benzyl derivative 30c. Looking along the N S bond,
owing to this pyramidalization,a pseudostaggered confor-
mation is observed,the phenyl
ring attached to the sulfur atom
is always arranged between the
two substituents on the nitrogen
atom,as exemplified in Figure 9
for 28. As mentioned above,in-
versions at this nitrogen atom
are strongly involved in the
conformational changes of the
substrates.
À
À
dominated by rotations around N C and C C single bonds
in combination with inversion vibrations at the nitrogen
atom of the sulfonamide (compare below). Thus the failure
of these substrates to react with the gold catalysts to give
phenols is clearly not due to steric effects of the substituents,
which would not allow the proper conformation to be occu-
pied for cyclization; the electronic effects of these substitu-
ents must be the cause of the lack of reactivity.
Conclusion
The observation that certain
substituents are tolerated in
Hence the results can be interpreted as follows: The fail-
ure of 1p to react can be assigned to the reduction of the
catalyst by the furyl alcohol as discussed above; the failure
of all three acceptor-substituted derivatives 1q–1s shows
that the acceptor inhibits the reaction. If the gold-catalyzed
gold-catalyzed phenol synthesis
Figure 9. The view along the
and others are not,that
a
À
N S bond of 28 shows a con-
bromo substituent is tolerated
formation typical of all the sul-
at a certain position and not at fonamides investigated.
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A. S. K. Hashmi et al.
crude product was purified by column chromatography on silica (petrol
ether (PE)/ethyl acetate (EA)/dichloromethane (DCM),5:1:5) to yield
11.0 mg (6%) of 2t as a colorless solid. Rf (PE/EA/DCM,5:1:5) =0.24.
M.p. 122–1248C; IR (neat): 3395,2951,2859,1744,1731,1625,1598,
another,and that other five-membered heterocycles do not
undergo similar reactions,is one part of the mechanistic
puzzle for this reaction; the final mechanistic picture must
also explain these facts. For the substituted furans it has
been shown that substituents that deactivate the p system of
the furan are not tolerated; molecular modeling confirmed
that there are no steric factors preventing these substrates
from occupying a reactive conformation.
The catalytic activity of [Ru3(CO)12] shows how general
the cycloisomerization reaction is for a d8-configurated com-
plex. The deoxygenation in the presence of a phosphane
ligand and a ruthenium complex demands further investiga-
tion and the para-Claisen rearrangements of the allyl ether
2c and the triflate of 2c show how the products might serve
as building blocks and be further converted in subsequent
syntheses.
1495,1453,1379,1361,1315,1260,1216,1149,1107,1079,1045,1017,
943,917,836,812,785,712,699,666,589,568,537 cm
À1
;
1H NMR
(CDCl3,500 MHz): d=2.08 (s,3H),2.40 (s,3H),4.59 (s,2H),4.60 (s,
2H),5.04 (s,2H),6.70 (d, J=7.7 Hz,1H),7.14 (d, J=7.7 Hz,1H),7.30
(d, J=8.1 Hz,2H),7.77 (d, J=8.1 Hz,2H),8.38 (s,1H) ppm; 13C NMR
(CDCl3,126 MHz): d=20.86 (q),21.48 (q),51.81 (t),54.12 (t),62.67 (t),
114.32 (d),120.53 (s),125.20 (s),127.61 (d,2C),129.78 (d,2C),132.66
(d),133.63 (s),139.82 (s),143.61 (s),151.08 (s),174.33 (s) ppm. MS (FAB
positive-ion,matrix: p-nitrobenzyl alcohol): m/z (%): 723 (1) [2M+H+],
494 (3) [M+Cs+],384 (5) [ M+Na+],362 (66) [ M+],302 (32),206 (16),
155 (15),146 (100),133 (38) [Cs +],91 (51),55 (44),43 (33). HRMS
(FAB positive-ion,matrix:
p-nitrobenzyl alcohol): calcd for
12
C
1H2014N116O532S1: 362.1062; found: 362.1070.
18
2u: According to the general procedure, 1u (55.0 mg,127 mmol) and
AuCl3 (1.92 mg,6.33 mmol,5.0 mol%) in acetonitrile (500 mL) were used.
The reaction was monitored by 1H NMR spectroscopy. After three days,
the crude product was purified by column chromatography on silica
(petrol ether/ethyl acetate 4:1) to yield 34.0 mg (62%) of 2u as a pale
yellow solid. M.p. 172–1738C. Rf (PE:EA,4:1) =0.20. IR (film): n˜ =3256,
Experimental Section
3108,2975,2875,1697,1625,1597,1527,1471,1340,1285,1157,1042,
À1
;
1H NMR (CDCl3,300 MHz): d=1.16 (s,
General methods: Melting points were taken by using a Fischer–Johns
Melting Apparatus and are uncorrected. IR spectra were recorded on a
Bruker IFS 28 FT-IR spectrometer. 1H and 13C NMR spectra were re-
corded on a Bruker Bruker AC 250,Bruker ARX 300 or Bruker ARX
500. NMR spectra were recorded in CDCl3,except when otherwise
stated. Chemical shifts are given in ppm relative to CDCl3 (1H, d=
7.26 ppm; 13C, d=77.16 ppm). LRMS and HRMS were taken on a Finni-
gan MAT 95 or a Varian MAT 711 spectrometer. All commercially avail-
able compounds were used without further purification.
949,854,813,736,690 cm
9H),4.64 (s,2H),4.66 (s,2H),5.03 (s,2H),6.71 (d,
J=7.7 Hz,1H),7.17
(d, J=7.7 Hz,1H),8.07 (d, J=9.0 Hz,2H),8.36 (d, J=9.0 Hz,1H),8.64
(s,1H) ppm; 13C NMR (CDCl3,75.5 MHz): d=27.41 (q,3C),39.03 (s),
52.12 (t),54.37 (t),63.04 (t),114.35 (d),121.07 (s),124.57 (d,2C),124.60
(s),128.72 (d,2C),133.11 (d),139.01 (s),143.00 (s),150.25 (s),151.40 (s),
182.05 (s) ppm; MS (DCI negative-ion,reactand gas: CH ): m/z (%): 434
4
(19) [M+],332 (100),258 (3),186 (5). HRMS (DCI negative-ion,reac-
tand gas: CH4): calcd for C20H22N2O7S: 434.1148; found: 434.1157; ele-
mental analysis calcd (%) for C20H22N2O7S (434.46): C 55.29,H 5.10,N
6.45; found: C 53.11,H 4.81,N 5.48.
General procedure for gold-catalyzed reactions: The test substrate was
dissolved in acetonitrile and a solution of the gold catalyst in acetonitrile
(10% w/w) was added. The reaction was monitored by either thin-layer
10: According to the general procedure, 9 (420 mg,949 mmol) and AuCl3
(28.8 mg,94.9 mmol,10 mol%) in acetonitrile (3.0 mL) were used. After
15 minutes,the reaction was stopped by cooling,the solvent removed in
vacuo,and the crude product purified by column chromatography on
silica (hexane/ethyl acetate,1:1) to yield 341 mg (77%) of 10 as a dark
yellow solid. Rf (H/EA,1:1) =0.6. IR (film,NaCl): n˜ =3482,3288,3146,
1
chromatography or by H NMR spectroscopy.
2l: According to the general procedure, 1l (700 mg,1.83 mmol) and
AuCl3 (27.7 mg,91 mmol,5.0 mol%) in acetonitrile (15 mL) were used.
After 24 h,a colorless precipitate was filtered,washed with water,metha-
nol,and diethyl ether and dried in vacuo to yield 255 mg (36%) of 2l.
3065,2957,2924,2874,2588,2257,1919,1686,1647,1597,1494,1451,
1374,1344,1162,1121,1090,1038,1018,912,814,734,703,673 cm
M.p. 235–2458C; IR (KBr): n˜ =3498,1578,1425,1323,1230,1138,1098,
1051,809,795,763,650 cm
À1
;
1H
À1
;
1H NMR (CDCl3,300 MHz): d=2.13 (s,
NMR (CDCl3,250 MHz): d=2.33 (s,3H),2.42 (s,3H),3.96 (s,2H),4.59
3H),2.41 (s,3H),4.49 (s,2H),4.54 (s,2H),5.54 (s,1H),7.09 (s,1H),(d,
J=8.3 Hz,2H),7.76 (d, J=8.3 Hz,2H) ppm;
13C NMR (CDCl3,
(s,2H),4.86 (s,1H),5.00 (s,1H),6.20 (d,
J=3.8 Hz,1H),7.06 (d, J=
126 MHz): d=13.03 (q),21.50 (q),52.96 (t),53.23 (t),109.57 (s),120.28
(s),122.73 (d),127.53 (d,2C),128.42 (s),129.86 (d. 2C),133.60 (s),
3.3 Hz,1H),7.36 (d, J=8.2 Hz,2H),7.42 (d, J=8.2 Hz,2H),7.62 (d, J=
8.3 Hz,2H),7.75 (d, J=8.4 Hz,2H) ppm; 13C NMR (CDCl3,62.9 MHz):
d=21.5 (q),21.7 (q),43.8 (t),49.1 (t),107.7 (t),107.8 (d),121.9 (d),122.8
(s),125.3 (s),127.1 (d,2C),127.5 (d,2C),129.3 (d,2C),130.4 (d,2C),
136.64 (s),143.77 (s),149.67 (s) ppm. MS (70 eV):
m/z (%): 383 (16)
[81BrÀM+],381 (17) [ 79BrÀM+],269 (11),267 (10),228 (90),226 (100),
157 (13),155 (21),91 (78); elemental analysis calcd (%) for
C16H16BrNO3S (382.28): C 50.27,H 4.22,N 3.66; found: C 50.25,H 4.33,
N 3.93.
132.7 (s),134.5 (s),135.5 (s),143.5 (s),145.8 (s) ppm; MS (70 eV):
(%): 442 (5) [M+],286 (19),199 (22),155 (37),91 (100),65 (16),44 (21),
18 (60).
m/z
2n: According to the general procedure, 1n (8.00 mg,24.8 mmol) and
AuCl3 (380 mg,1.2 mmol,5.0 mol%) in acetonitrile (500 mL) were used.
After 26 h,the product 2n was characterized by 1H NMR spectroscopy.
14: According to the general procedure, 13 (37.0 mg,207 mmol) and Na-
A
were used. After 15 h at 508C,the product was characterized by 1H
NMR spectroscopy. 1H NMR (CD3CN,300 MHz): d=2.01 (s,3H),2.29
(s,3H),5.06 (d, J=11.1 Hz,1H),5.42 (d, J=17.5 Hz,1H),6.48 (dd, J=
11.1,17.5 Hz,1H) ppm.
1H NMR (CD3CN,250 MHz): d=3.07 (s,6H),3.27 (s,3H),4.72 (d,
J=
5.4 Hz,4H),6.85 (d, J=7.6 Hz,1H),7.21 (d, J=7.6 Hz,1H) ppm; 13C
NMR (CD3CN,62.9 MHz): d=15.2 (q),52.9 (q,2C),68.9 (t),70.9 (t),
115.0 (d),119.2 (s),125.6 (s),132.2 (s),132.3 (d),150.3 (s) ppm.
16: According to general procedure, 15 (30.0 mg,124 mmol) and Na-
2o: According to the general procedure, 1o (20.7 mg,61.3 mmol) and
AuCl3 (9.27 mg,3.06 mmol,5.0 mol%) in acetonitrile (500 mL) were used.
The reaction was monitored by 1H NMR spectroscopy. After 80 h,80%
of the starting material had been converted,according to characteristic
signals of phenolic protons at d=6.77 (d, J=8.3 Hz,1H) and 7.24 ppm
(d, J=8.3 Hz,1H).
G
were used. After 15 h at 508C,the crude product was purified by column
chromatography on silica (petrol ether/ethyl acetate,5:1) to yield 9.7 mg
(30%) of 16 as a colorless oil. Rf (PE:EA,5:1) =0.38. IR (neat): n˜ =
2922,2360,1682,1646,1573,1546,1486,1449,1421,1125,977,950 cm
1H NMR (CDCl3,300 MHz): d=2.26 (s,3H),5.26 (d, J=11.1 Hz,1H),
5.71 (d, J=17.5 Hz,1H),6.57 (dd, J=11.1,17.5 Hz,1H),7.41–7.48 (m,
2t: According to the general procedure, 1t (193 mg,531 mmol) and
AuCl3 (8.05 mg,26.5 mmol,5.0 mol%) in acetonitrile (3.0 mL) were used.
The reaction was monitored by 1H NMR spectroscopy. After 24 h,the
3H),8.01–8.08 (m,2H) ppm; 13C NMR (CDCl3,75.5 MHz): d=11.9 (q),
113.1 (t),121.3 (d),126.3 (d),127.4 (s),128.7 (d),130.3 (d),135.1 (s),
5812
www.chemeurj.org
ꢁ 2006 Wiley-VCH Verlag GmbH & Co. KGaA,Weinheim
Chem. Eur. J. 2006, 12,5806 – 5814

Gold-Catalyzed Phenol Synthesis
FULL PAPER
1
145.2 (s),159.8 (s) ppm; MS (EI,70 eV): m/z (%): 185 (100) [M+],116
(28),104 (19),86 (20),84 (30); HRMS (EI,70 eV): calcd for C 12H11NO:
185.0841; found 185.0840.
712,665 cm À1; H NMR (CDCl3,250 MHz): d=2.23 (s,3H),2.40 (s,3H),
4.36 (brd, J=5.5 Hz,2H),4.58 (s,2H),4.65 (s,2H),5.26 (dd, J=1.2,
10.4 Hz,1H),5.37 (dd, J=1.5,17.1 Hz,1H),6.03 (ddt, J=10.4,17.1,
22.9 Hz,1H),6.80 (d, J=7.6 Hz,1H),7.05 (d, J=7.6 Hz,1H),7.31 (d,
J=7.9 Hz,2H),7.76 (d, J=8.2 Hz,2H) ppm;
13C NMR (CDCl3,
19: A solution of octacarbonyldicobalt (260 mg,760 mmol) in diethyl
ether (ca. 20 mL) was treated with a solution of 4-methyl-N-(5-methylfur-
an-2-ylmethyl)-N-prop-2-ynylbenzenesulfonamide (230 mg,759 mmol) in
diethyl ether (ca. 5.0 mL) under argon. After stirring the reaction mix-
ture for 72 h,the crude product was purified by column chromatography
on silica (hexane(H)/ethyl acetate,5:1) to give 330 mg (74%) of 61 as
dark crystals. M.p.: 1288C. Rf (H/EA,5:1) =0.34. IR (neat): n˜ =2370,
62.9 MHz,): d=15.8 (q),21.3 (q),51.9 (t),53.5 (t),73.0 (t),117.5 (d),
117.8 (t),127.4 (d,2C),128.1 (s),129.7 (d,2C),131.1 (d),133.3 (d),133.5
(s),135.6 (s),143.5 (s),152.2 (s) ppm; one s not detected; MS (70 eV): m/
z (%): 342 (11) [M+],313 (11),302 (18),301 (100),187 (23),158 (20),
155 (34),146 (80),118 (26),91 (92),41 (31); elemental analysis calcd
(%) for C19H21NO3S (343.2): C 66.48,H 6.12,N 4.08; found: C 66.45,H
5.85,N 4.18.
2344,2094,2057,2019,1654,1560,1432,1347,1327,1220,1156,1092,
À1
1068,1021,972,915,886,814,790,762,730 cm
;
1H NMR (CDCl3,
25: A solution of 24 (60.0 mg,175 mmol) in triethylbenzene (ca. 2.0 mL)
was heated for 3 h at 1858C under argon. The crude product was purified
by column chromatography on silica (hexane/ethyl acetate/dichlorome-
thane,6:1:2) to yield 30.8 mg (51%) of 25 as a colorless solid. M.p. 169–
1748C. Rf (H/EA/DCM,6:1:2) =0.16; IR (film): n˜ =3448,2922,2371,
250 MHz): d=2.11 (s,3H),2.44 (s,3H),4.48 (s,2H),4.52 (s,2H),5.84
(d, J=2.2 Hz,1H),5.96 (s,1H),6.02 (d, J=3.0 Hz,1H),7.29 (d, J=
8.2 Hz,2H),7.71 (d, J=8.2 Hz,2H) ppm; 13C NMR (CDCl3,62.9 MHz):
d=13.3 (q),21.5 (q),29.7 (t),30.9 (t),73.3 (d),89.7 (s),106.3 (d),111.0
(d),127.4 (d,2C),129.5 (d,2C),137.2 (s),143.2 (s),147.0 (s),152.6 (s),
199.2 (CO) ppm; MS (70 eV): m/z (%): 561 (5),533 (13),505 (18),477
(4),449 (8),421 (65),28 (100); elemental analysis calcd (%) for
C22H17Co2NO9S (589.1): C 44.85,H 2.89,N 2.38; found: C 45.01,H 2.97,
N 2.54.
2345,1701,1637,1598,1496,1458,1341,1219,1160,1098,1017,916,814,
À1
720,708,665 cm
;
1H NMR ([D6]acetone,250 MHz): d=2.14 (s,3H),
2.37 (s,3H),3.17 (d, J=6.5 Hz,2H),4.53 (s,4H),4.93 (d,
J=4.0 Hz,
1H),4.96,(d, J=2.4 Hz,1H),5.83 (ddt, J=2.4,4.0,6.5 Hz,1H),6.79 (s,
1H),7.40 (d, J=8.0 Hz,2H),7.77 (d, J=8.3 Hz,2H) ppm; 13C NMR
([D6]acetone,62.9 MHz): d=15.8 (q),21.3 (q),37.2 (t),52.7 (t),53.6 (t),
115.6 (t),123.4 (s),124.7 (s),126.0 (s),128.4 (d,2C),130.6 (d,2C),131.8
(d),134.7 (s),137.4 (d),144.7 (s),149.1 (s) ppm; one s not detected; MS
(70 eV): m/z (%): 343 (39) [M+],188 (100),160 (13),91 (26); elemental
analysis calcd (%) for C19H21NO3S (343.2): C 66.48,H 6.12,N 4.08;
found: C 66.24,H 5.94,N 4.19.
20: N-Methylmorpholine N-oxide (310 mg,2.65 mmol) was added to a
solution of 19 (260 mg,441 mmol) and norbornene (49.9 mg,530 mmol) in
dichloromethane (ca. 5 mL) and the reaction mixture was stirred for 16 h
at ambient temperature. After filtration and removal of the solvent in
vacuo,the crude product was purified by column chromatography on
silica (hexane/ethyl acetate,1:1) to give 153 mg (81%) of 20 as a yellow
oil. Rf (H/EA,1:1) =0.54. IR (film): n˜ =3278,3032,2957,2874,2254,
26: According to the general procedure, 1c (800 mg,2.64 mmol) was
treated with a solution of AuCl3 (400 mg,132 mmol,5 mol%) in CD 3CN
(10% w/w). After removal of the solvent in vacuo,the residue was redis-
solved in acetone and diisopropylethylamine (DIPEA) (900 mL,
1918,1694,1630,1598,1560,1522,1494,1449,1340,1221,1160,1093,
1020,912,815,733 cm
À1
;
1H NMR (CDCl3,250 MHz): d=0.87 (s,2H)
1.21 (s,1H),1.24 (s,2H),1.27 (s,1H),1.57 (m,3H),2.09 (s,3H),2.31
(brs,1H),2.40 (s,3H),2.52 (brs,1H),3.86 (s,2H),4.28 (s,2H),5.75
(brs,1H),5.97 (d, J=3.1 Hz,1 Hz),7.25 (d, J=8.3 Hz,2H),7.65 (d, J=
8.3 Hz,2H) ppm; 13C NMR (CDCl3,62.9 MHz): d=13.4 (q),21.4 (q),
28.3 (t),29.0 (t),31.1 (t),37.9 (d),38.9 (d),42.7 (t),45.0 (t),48.4 (d),54.4
(d),106.3 (d),110.9 (d),127.5 (d,2C),129.5 (d,2C),136.0 (s),137.4 (s),
5.28 mmol)
and
N,N-bis(trifluormethanesulfonyl)aniline
(1.89 g,
5.28 mmol) were added. The reaction mixture was stirred for 18 h at am-
bient temperature,the solvent evaporated,and the residue redissolved in
dichloromethane and extracted with saturated NaHCO3 solution. The
crude product was purified by column chromatography on silica (hexane
(H)/acetone (A),2:1) to give 642 mg (58%) of 26 as a pale-yellow solid.
143.7 (s),143.9 (s),152.3 (s),161.7 (d),209.7 (C
=O) ppm; MS (70 eV):
m/z (%): 425 (1) [M+],270 (78),176 (61),18 (100).
M.p. 110–1118C. Rf (H/A,2:1) =0.46. IR (film): n˜ =2369,2344,1654,
21: Compound 1c (75.1 mg,248 mmol) was added to a solution of [CpRu-
(PPh3)2Cl] (60.0 mg,82.6 mmol) and NH4PF6 (16.2 mg,99.1 mmol) in
À1
1560,1458,1406,1352,1215,1166,1137,1097,1034,970,926,840 cm
;
ACHTREUNG
1H NMR (CDCl3,250 MHz): d=2.36 (s,3H),2.43 (s,3H),4.63 (s,2H),
methanol (ca. 50 mL) and the reaction mixture was stirred for 4 h at am-
bient temperature. After removal of the solvent in vacuo,the residue was
redissolved in dichloromethane and the insoluble white precipitate fil-
tered off. The crude product was obtained by precipitation with diethyl
ether and then dried in vacuo. 31P{1H} NMR (CDCl3,162 MHz): d=
4.73 (s,2H),7.08 (d, J=7.7 Hz,1H),7.22 (d, J=7.7 Hz,1H),7.35 (d, J=
8.4 Hz,2H),7.78 (d, J=8.3 Hz,2H) ppm; 13C NMR (CDCl3,62.9 MHz):
d=16.3 (q),21.5 (q),51.8 (t),53.7 (t),121.0 (s),122.5 (d),127.6 (d,2C),
129.9 (d,2C),130.0 (s),130.9 (s),132.2 (d),133.4 (s),137.4 (s),141.9 (s),
144.0 (s) ppm; 19F NMR (CDCl3,235.3 MHz): d=À74.9 (s) ppm. MS
(70 eV): m/z (%): 435 (25) [M+],281 (13),280 (100),147 (57),91 (49);
elemental analysis calcd (%) for C17H16F3NO5S2 (435.3): C 46.91,H 3.68,
N 3.22; found: C 47.11,H 3.71,N 3.22.
À143.0 (sept., J=4.4 Hz,PF À),40.8 (d, J=26.8 Hz),41.3 (d, J=
6
26.8 Hz) ppm; FAB-MS (positive-ion): m/z (%): 994 (12) [cation],719
(19),429 (48),352 (12),279 (100),183 (18),133 (32),107 (38),91 (53),69
(65),55 (81).
23: PiPr3 (201 mg,1.3 mmol) was added to
a
solution of
[Ru(methylallyl)2(cod)] (200 mg,627 mmol) in dichloromethane (ca.
ACHTREUNG
25 mL) and acetone (16 mL) and the mixture was cooled to À208C.
After addition of HCl in methanol (1.25m,1.3 mmol,1.0 mL,Fluka) and
stirring for 30 min at À208C, 1c (950 mg,3.1 mmol) was added and the
reaction mixture stirred for another 20 h at ambient temperature. 1H
NMR (CDCl3,250 MHz): d=1.24 (dd, J=7.0,13.9 Hz,36H),2.14 (m,
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft (Ha 1932/6-2),the
Fonds der Chemischen Industrie (Chemiefonds fellowship for J.P.W.),
and the Karl-Ziegler-Stiftung for their generous support. Gold salts were
donated by Umicore.
6H),2.21 (s,3H),2.43 (s,3H),4.03 (d,
J=2.5 Hz,2H),4.38 (s,2H),4.58
(s,1H),5.87 (d, J=2.8 Hz,1H),6.16 (d, J=2.8 Hz,1H),7.30 (d, J=
8.2 Hz,2H),7.74 (d,
J=8.2 Hz,2H) ppm; 31P{1H} NMR (162 MHz,
CDCl3): d=59.7 (s) ppm.
24: Allylic bromide (500 mL,6.0 mmol) was slowly added to a solution of
2c (240 mg,792 mmol) and Cs2CO3 (535 mg,1.64 mmol) in acetonitrile
(ca. 30 mL) and the reaction mixture was stirred for 20 h at ambient tem-
perature. After removal of the solvent in vacuo,the crude product was
purified by column chromatography on silica (hexane/ethyl acetate/di-
chloromethane,8:1:1) to give 100 mg (37%) of 24 as a colorless solid.
M.p. 91–968C. Rf (H/EA/DCM,8:1:1) =0.22. IR (film,NaCl): n˜ =2923,
2366,2344,1596,1458,1348,1315,1215,1164,1098,1054,998,930,813,
[1] For reviews on the hot topic,gold catalysis,see: a) A. Hoffmann-
Rçder,N. Krause, Org. Biomol. Chem. 2005, 3,387–391; b) A.
Arcadi,S. Di Giuseppe,
Curr. Org. Chem. 2004, 8,795–812;
c) A. S. K. Hashmi, Gold Bull. 2004, 37,51—65; d) A. S. K. Hashmi,
Gold. Bull. 2003, 36,3–9.
[2] A. S. K. Hashmi,T. M. Frost,J. W. Bats, J. Am. Chem. Soc. 2000,
122,11553–11554.
Chem. Eur. J. 2006, 12,5806 – 5814
ꢁ 2006 Wiley-VCH Verlag GmbH & Co. KGaA,Weinheim
www.chemeurj.org
5813

A. S. K. Hashmi et al.
[3] B. Martin-Matute,D. J. Cardenas,A. M. Echavarren, Angew. Chem.
2001, 113,4890–4893; Angew. Chem. Int. Ed. 2001, 40,4754–4757.
[4] For recent compilations of this,see: a) C. Bruneau, Angew. Chem.
2005, 117,2380–2386; Angew. Chem. Int. Ed. 2005, 44,2328–2334;
b) C. Nevado,A. M. Echavarren, Synthesis 2005,167–182; c) A. M.
[16] Specifically,compounds 80, 83,and 84 in ref. [11].
[17] a) B. F. G. Johnson,J. Lewis,D. A. Pippard, J. Chem. Soc. Dalton
Trans. 1981,407–412; b) J. Lewis,P. R. Raithby, J. Organomet.
Chem. 1995, 500,227–237; c) E. W. Ainscough,A. M. Brodie,R. K.
Coll,A. J. A. Mair,J. M. Waters, J. Organomet. Chem. 1996, 509,
259–264; d) E. W. Ainscough,A. M. Brodie,R. K. Coll,B. A.
Coombridge,J. M. Waters, J. Organomet. Chem. 1998, 556,197–205.
[18] A. J. Deeming, Adv. Organomet. Chem. 1986, 26,1–96.
Echavarren,C. Nevado,
Chem. Soc. Rev. 2004, 33,431–436;
d) A. M. Echavarren,M. Mendez,M. P. Munoz,C. Nevado,B.
Martin-Matute,C. Nieto-Oberhuber,D. J. Cµrdenas,
Chem. 2004, 76,453–463.
Pure Appl.
[19] CCDC-283523 (1c),CCDC-283525
CCDC-283524 (1i),CCDC-283526
CCDC-281917 (1l),CCDC-283514
CCDC-283511 (1s),CCDC-281914
(
(
(
1e),CCDC-283531
1j),CCDC-283527
1m),CCDC-283515
( 1t),CCDC-283530
(
(
(
(
1 f),
1k),
1n),
2b),
[5] A. S. K. Hashmi,T. M. Frost,J. W. Bats, Org. Lett. 2001, 3,3769–
3771.
[6] A. S. K. Hashmi,M. Rudolph,J. P. Weyrauch,M. Wçlfle,W. Frey,
J. W. Bats, Angew. Chem. 2004, 116,6707–6709; Angew. Chem. Int.
Ed. 2004, 43,6545–6547.
[7] A. S. K. Hashmi,M. Rudolph,J. P. Weyrauch,M. Wçlfle,W. Frey,
J. W. Bats, Angew. Chem. 2005, 117,2858–2861; Angew. Chem. Int.
Ed. 2005, 44,2798–2801.
[8] A. S. K. Hashmi,T. M. Frost,J. W. Bats, Catal. Today 2001, 72,19–
72.
CCDC-283529 (2c),CCDC-283528 ( 2j),CCDC-283513 ( 9),CCDC-
283512 (11),CCDC-281916 ( 17),CCDC-281913 ( 18),CCDC-283519
(19),CCDC-283516 ( 22),CCDC-283517 ( 24),CCDC-283518 ( 26),
CCDC-283520 (28),CCDC-283521 ( 30a),CCDC-283522 ( 30b),and
CCDC-281915 (30c) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
[9] A. S. K. Hashmi,L. Grundl, Tetrahedron 2005, 61,6231–6236.
[10] A. S. K. Hashmi,L. Ding,J. W. Bats,P. Fischer,W. Frey,
Chem. Eur.
J.
[20] H. Schmidbaur,A. Schier, Sci. Synth. 2004, 3,691–761.
[21] For the few examples,see: S. von Angerer,W. Tochtermann,
Houben Weyl, Vol. 9d,Thieme,Stuttgart, 1998,pp. 1–64,specifically
p. 42.
J. 2003, 9,4339–4345.
[11] B. Martín-Matute,C. Nevado,D. J. Cµrdenas,A. M. Echavarren,
Am. Chem. Soc. 2003, 125,5757–5766.
[12] Specifically,compound 55 on p. 5761 of ref. [11].
[13] In the case of the aldehyde,gold is closely related to the reactivity
of Tollenꢀs reagent.
[14] For example,Rh-catalyzed decarbonylation: M. C. Baird,J. T.
Mague,J. A. Osborn,G. Wilkinson, J. Chem. Soc (A) 1967,1347–
1360.
[22] N. L. Allinger,Y. H. Yuh,J.-H. Lii, J. Am. Chem. Soc. 1989, 111,
8551–8566.
[23] a) J. W. Ponder,TINKER: Software Tools for Molecular Design,4.2
ed.,Washington University School of Medicine,Saint Louis,MO,
2004; b) J. W. Ponder,F. M. Richards, J. Comput. Chem. 1987, 8,
1016–1024.
[15] For example,see: a) W. H. Perkin, J. Chem. Soc. 1889, 55,63–90
(especially p. 71); b) W. H. Perkin, J. Chem. Soc. 1890, 57,992–1106
(especially p. 1014).
Received: October 12,2005
Revised: February 9,2006
Published online: May 23,2006
5814
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ꢁ 2006 Wiley-VCH Verlag GmbH & Co. KGaA,Weinheim
Chem. Eur. J. 2006, 12,5806 – 5814