Oxidative gold catalysis meets photochemistry - Synthesis of benzo[a]fluorenones from diynes

Article abstract of DOI:10.1002/adsc.201400969

Diynes bearing one terminal and one triarylmethylsubstituted alkyne were converted into complex benzofluorenone derivatives via a one-pot process involving a gold-catalyzed step followed by a photocyclization/oxidation. In the first step an Noxide was used to position-selectively generate an a-oxo carbenoid at the terminal alkyne which after a regioselective 1,6-carbene transfer along the tethered tritylalkyne and a subsequent aryl 1,2-shift furnished tetraphenylethylene-like derivatives. These intermediates were successfully transformed to fluorenones via oxidative photocyclization.

Full text of DOI:10.1002/adsc.201400969

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DOI: 10.1002/adsc.201400969
Oxidative Gold Catalysis Meets Photochemistry – Synthesis of
Benzo[a]fluorenones from Diynes
Pascal Nçsel,a Setareh Moghimi,a Christoph Hendrich,a Marten Haupt,a
Matthias Rudolph,a Frank Rominger,+a and A. Stephen K. Hashmia,*
a
Organisch-Chemisches Institut, Ruprecht-Karls-Universitꢀt Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg,
Germany
Fax : (+49)-6221-54-4205; e-mail: hashmi@hashmi.de (homepage: http://www.hashmi.de)
+
Crystallographic investigation.
Received: October 8, 2014; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201400969.
Abstract: Diynes bearing one terminal and one tri-
arylmethyl-substituted alkyne were converted into
complex benzofluorenone derivatives via a one-pot
process involving a gold-catalyzed step followed by
a photocyclization/oxidation. In the first step an N-
oxide was used to position-selectively generate an
a-oxo carbenoid at the terminal alkyne which after
a regioselective 1,6-carbene transfer along the teth-
ered tritylalkyne and a subsequent aryl 1,2-shift fur-
nished tetraphenylethylene-like derivatives. These
intermediates were successfully transformed to fluo-
renones via oxidative photocyclization.
bene transfer over a tethered alkyne (Scheme 1,
upper part).[6]
In this context, we now wanted to explore whether
bulky aromatic substituents on the non-terminal
alkyne would open a new access to interesting extend-
ed p-systems via a domino sequence composed of
a position-selective a-oxo-gold carbenoid formation,
regioselective gold carbenoid transfer, pericyclic 1,2-
shift and a chemoselective photocatalytic electrocyclic
ring closure/oxidative aromatization (using an oxidant
different from the oxidant of the a-oxo-gold carbe-
noid formation). The indenone derivatives 4 would
contain two cis-stilbene-like substructures. Mallory
and co-workers investigated the oxidative photocycli-
zation of stilbenes and related systems in the early
1960s.[7] Induced by light, stilbenes may undergo
Keywords: arenes; carbene ligands; extended p-sys-
tems; fluorenones; gold; photoreactions
Since its beginning in 2000,[1] the field of homogene-
ous gold catalysis has become a source of important
new synthetic methods for organic synthesis.[2] In 2007
Zhang and Toste[3] published the combination of al-
kynes and N-oxides in homogeneous gold catalysis.
This combination can serve as a safe and scalable sub-
stitute for carbonyl-substituted diazo compounds. The
use of the resulting a-oxo carbenoids for the design
of new reactions has attracted significant attention.[4]
All of the known procedures involve the direct chemi-
cal transformation of the initially formed gold carbe-
noid by the attack of an external or internal nucleo-
phile. Recently we could prove that diynes – in addi-
tion to their use in dual activation chemistry[5] – can
also serve as valuable precursors for oxidative gold
catalysis, opening new synthetic routes to interesting
organic scaffolds. These reactions are based on a car-
Scheme 1. Upper part: pathway for tert-butyl-substituted
substrates 1; lower part: envisioned sequence for trityl-sub-
stituted diyne systems 3.
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Pascal Nçsel et al.
Scheme 2. No conversion of 3a with dual activation catalyst 5.
Scheme 3. Formation of the intermediary indenone 4b and subsequent photocyclization/oxidation to 8b.
trans-cis isomerization and subsequent ring closure to
Next, we focussed on optimizing the yield of the
unstable dihydrophenanthrenes which can be further gold-catalyzed step. Various solvents, catalysts and N-
oxidized to the corresponding phenanthrene deriva- oxides were screened and the amount of 4a formed
1
tives in the presence of a stoichiometric oxidizing was monitored by H NMR spectroscopy (for further
agent such as iodine or molecular oxygen.
details see the Supporting Information). The use of
In a first experiment with the 1,5-diyne 3a we 1.50 equivalents of 8-ethylquinoline N-oxide in combi-
wanted to investigate whether or not competing dual nation with 5 mol% of PPh3AuNTf2 turned out to be
activation of the substrates is observed with the steri- best suited. In acetonitrile at 608C the transformation
cally demanding triphenylmethyl substituent. This was was typically completed within 2 h. However, due to
crucial as such a vinylidene pathway would provide the tendency to decompose and possible autooxida-
undesired side products – Zhangꢂs group demonstrat- tion an isolated yield for indenone 4a could not be de-
ed that even the N-oxides can serve as a base for the termined.
initiation of the dual catalysis cycle.[5a] However, de-
After optimization of the gold-catalyzed step we fo-
spite the use of high catalyst loadings of the dual acti- cussed on the photocyclization/oxidation process.
vation catalyst 5[8] as well as prolonged reaction times Based on the structural analogy of our system to
and increased temperatures, no conversion of com- those reported by Mallory and Katz,[10] we investigat-
pound 3a to 6 could be detected (Scheme 2). This sug- ed the transformation under their previously pub-
gests that the steric bulk of this system prevents the
formation of a benzofulvene product 6 by the dual ac-
tivation mechanism.
Thus we could rule out competing dual catalysis
pathways and turned our focus to the oxidative cycli-
zation chemistry. With the dimethyl-substituted 3b,
5 mol% of XPhosAuNTf2 and 1.5 equivalents of 3,5-
dibromopyridine N-oxide, the formation of the in-
tensely coloured indenone product 4b was observed
1
by H NMR, which is a successful transfer of our pre-
viously published work (Scheme 3).[6a] However, the
product turned out to be unstable – it decomposed.
Among the decomposition products was an orange
crystalline solid, which was identified by X-ray crystal
structure analysis as the desired benzo[a]fluorenone
derivative 8b (Figure 1).[9] Even without irradiation
and external oxidants (apart from air) trace amounts
of the final product could be detected. Compound 8b
is most probably formed via oxidation of a dihydro-
benzo[a]fluorenone intermediate 7b.
Figure 1. Solid state molecular structure of 8b.
2
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Oxidative Gold Catalysis Meets Photochemistry
Scheme 4. Optimized conditions for the synthesis of 8a.
lished reaction conditions in order to further improve Table 1. Formation of substituted benzo[a]fluorenone deriv-
atives 8.
the yield of 8a.
Saturation of the solvent with oxygen and use of
catalytic amounts of iodine (5 mol%) as reported by
Mallory only afforded 8a in a moderate yield of 45%
over the two steps after irradiating for 90 min. Much
better results were obtained by using Katzꢂs modifica-
tion that employs 1.3 equiv. of iodine and a high
excess of propylene oxide (typically 350 equiv.) as HI
scavenger. This protocol afforded 70% of 8a in
a clean transformation without the need for further
chromatographic work-up (Scheme 4). The final prod-
uct simply precipitates from the acetonitrile solution.
Product
Yield
Time catalysis/
irradiation [h]
8a R1 =H; R2 =H; R3 =H
70%
79%
2/0.5
2/1
2.5/0.75
3.5/0.5
2/1
8b R1 =H; R2 =Me; R3 =Me
8c R1 =H; R2 =OMe; R3 =OMe 41%
As
a control experiment 4a was reacted with
8d R1 =H; R2 =Me; R3 =Me
8e R1 =H; R2,R3 =OCH2O
8f R1,R2 =OCH2O; R3 =H
8g R1 =H; R2 =F; R3 =H
8h R1 =H; R2 =NO2; R3 =H
8i R1 =F; R2 =H; R3 =H
8j R1 =H; R2 =H; R3 =Me
78%
49%
68%[a]
71%
1.3 equiv. of iodine under light exclusion. No conver-
sion at all was observed which emphasizes the neces-
sity of light for the second oxidative cyclization step.
An attempt to induce a second electrocyclic ring
closure involving the two remaining phenyl moieties
in product 8a with the help of DDQ-based procedures
failed.[11] In addition, prolonged irradiation times and
further excess of oxidants did not lead to the forma-
tion of dibenzochrysene derivatives either.
After optimization of both the gold-catalyzed reac-
tion step and the oxidative photocyclization we tried
to widen the scope of the reaction. First, the substrate
was varied by altering the substituents on the aromat-
ic backbone. The results are displayed in Table 1. All
conversions involve the transfer of the intermediary
12/1
12/1
35%[a,b] 12/1
66%[a]
69%
12/0.75
3/1
[a]
7.5 mol% catalyst.
[b]
Additional 0.5 equiv. of 8-ethylquinoline-N-oxide used;
concentration typically 290 mM, 608C, CH3CN, irradia-
tion: conducted in a 25-mL quartz tube photoreactor
with outer cooling jacket; 400 W mercury high-pressure
lamp.
formed indenone derivative 4 (without the need of derivatives (3k fluorine, 3l chlorine, 3m bromine)
a purification step) into a quartz tube photoreactor were well tolerated and all gave similar good yields of
and subsequent irradiation.
about 70%. Substrate 3p with an electron-donating
The reaction time for the gold-catalyzed step varied trityl moiety (OMe) provided 83% of 4p and was
between 2 and 12 h. Electron-withdrawing substitu- complete within just 15 min of irradiation. With un-
ents at the aromatic backbone induced longer reac- symmetrically substituted trityl derivatives in all cases
tion times (and in some cases required higher catalyst (Ph versus anisyl; Ph versus 4-F-C6H4; Ph versus Me;
loadings). Concerning the photochemical step, all of Ph versus Cy) inseparable mixtures of different iso-
1
the transformations were generally fast and for all mers (as determined by H and 19F NMR) were ob-
substrates completed within one hour or less. The tained.
overall yields ranged from 35% to 79% over both
Our mechanistic proposal, which is in accordance
steps. A detailed discussion of the electronic effect on with previously published work, is depicted in
the overall yield is difficult, since the intermediary Scheme 5. Oxygen transfer from the N-oxide 9 to the
formed indenones were not isolated and thus no yield gold-activated triple bond gives the a-oxo carbenoid
for the first step could be determined.
II. Then this carbenoid is transferred onto the second
Secondly, various substrates with substituted trityl alkyne, leading to the vinyl carbenoid intermediate
groups were investigated (Table 2). Halide substituted Vb. As described before,[12] this may either happen in
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Table 2. Variation of the substituents on the trityl alkyne
moiety, R=2-ethynylbenzene.[a]
Scheme 6. No oxygen transfer to the internal alkyne 11.
Product
Yield
Time catalysis/irradiation [h]
8k X=F
69%
69%
71%
69%
83%
1.5/0.5
1.25/1
1/1.25
2/0.5
8k X=Cl
8k X=Br
8k X=Me
8k X=OMe
Scheme 7. Oxidative cyclization of 12 to dihydroindenone
13.
2/0.25
[a]
Concentration typically 290 mM, 608C, CH3CN, irradia-
tion: conducted in a 25-mL quartz tube photoreactor
with outer cooling jacket; 400 W mercury high-pressure
lamp.
We investigated if a phenyl- and trityl-substituted
alkyne can also form an a-oxo gold carbenoid, which
À
possibly undergoes subsequent C H insertion at one
of the neighbouring phenyl moities. However, 11
failed to give any conversion with different N-oxides
a concerted process or via a cylcopropenation (inter- and gold catalysts (Scheme 6), which shows why the
mediate III) and a following ring opening. Subsequent oxygen transfer in substrates 3 goes specifically to the
1,2-migration of the phenyl group onto the carbenoid terminal alkyne.
carbon and protodeauration leads to the indenone
On the other hand, the unsubstituted trityl alkyne
product 4 and releases the catalyst. Upon irradiation 12 with 1.5 equiv. of the 3,5-dibromopyridine N-oxide
4 forms dihydrophenanthrene intermediate 7, which in the presence of 10 mol% of XPhosAuNTf2 yielded
under the employed reaction conditions is oxidized to the dihydroindenone 13 (Scheme 7), the structure of
the final benzo[a]fluorenone product 8.
which was unambiguously confirmed by an X-ray
Scheme 5. Mechanistic proposal.
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Oxidative Gold Catalysis Meets Photochemistry
quinoline-1-oxide (44.7 mg, 258 mmol) and 5 mol%
PPh3AuNTf2 (6.36 mg, 8.60 mmol) were added to the solu-
tion. After stirring for 2 h at 608C, the mixture was trans-
ferred into the photoreactor. 1.30 equiv. iodine (56.8 mg,
224 mmol) and 350 equiv. propylene oxide (3.50 g, 4.22 mL,
60.2 mmol) were added. The solution was irradiated for
0.5 h and treated according to the general procedure. An
orange solid was obtained; yield: 46.0 mg (120 mmol, 70%);
mp 1438C; Rf (silica gel, PE/EA=10:1)=0.46; IR (ATR):
˜
n=3055, 1694, 1558, 1441, 1246, 1031, 960, 745, 730, 723,
701 cmÀ1 1H NMR (CDCl3, 400 MHz): d=5.97 (d, JH,H
7.7 Hz, 1H), 7.02 (t, JH,H =7.5 Hz, 1H), 7.12–7.18 (m, 5H),
7.23–7.35 (m, 7H), 7.42 (d, JH,H =8.6 Hz, 1H), 7.59 (t, JH,H
;
=
=
7.3 Hz, 2H), 9.19 (d, JH,H =8.6 Hz, 1H); 13C NMR (CDCl3,
125 MHz): d=123.3 (d), 123.6 (d), 124.4 (d), 126.5 (s), 126.8
(d), 127.2 (d), 127.5 (d), 127.7 (d), 127.8 (d, 2C), 128.3 (d,
2C), 128.8 (d), 129.1 (d), 129.9 (s), 130.2 (d, 2C), 130.6 (d,
2C), 133.6 (s), 134.0 (d), 135.0 (s), 135.2 (s), 138.2 (s), 138.6
(s), 144.1 (s), 144.3 (s), 147.1 (s), 195.5 (s); MS (EI+, 70 eV):
m/z (%)=382 (100), 381 (9), 352 (8), 351 (7), 350 (9), 175
(7); HR-MS: m/z=382.1358, calcd. for C29H18O+:382.1352
[M+]; UV/VIS (DCM): l (log e)=249 (4.59), 273 (4.72), 300
(4.27), 370 (3.69), 385 (3.74), 425 (3.25), 441 nm (3.21).
Figure 2. Solid state molecular structure of 13.
crystal structure analysis (Figure 2). This is in com-
plete accord with work of Gagoz et al.[13] on sterically
less hindered alkynes.
8,9-Dimethyl-5,6-diphenyl-11H-benzo[a]fluoren-11-one
(8b): According to the general procedure, 1.00 equiv of [3-
(2-ethynyl-4,5-dimethylphenyl)prop-2-yne-1,1,1-triyl]triben-
zene (3b, 60.3 mg, 152 mmol) was dissolved in 600 mL aceto-
nitrile. 1.50 equiv. of 8-ethylquinoline 1-oxide (39.5 mg,
228 mmol) and 5 mol% PPh3AuNTf2 (5.62 mg, 7.60 mmol)
were added to the solution. After stirring for 2 h at 608C,
the mixture was transferred into the photoreactor.
1.30 equiv. iodine (50.2 mg, 198 mmol) and 350 equiv. propyl-
ene oxide (3.08 g, 3.71 mL, 53.2 mmol) were added. The so-
lution was irradiated for 1.5 h and treated according to the
general procedure. An orange solid was obtained; yield:
49.0 mg (119 mmol, 79%); mp 2358C; Rf (silica gel, PE/
In conclusion, we have succeeded in generating
highly functionalized benzo[a]fluorenones in good
yields by means of a gold-catalyzed carbenoid transfer
over a tethered alkyne and a subsequent photocycliza-
tion/oxidation of the intermediary formed reactive in-
denones. Our systems show a high potential for varia-
tion either on the aromatic backbone, the alkyne or
the trityl moiety, thus allowing the synthesis of ex-
tended p-systems from easily accessible reactants in
a one-pot process. The combination of gold catalysis
and photochemistry in a one-pot manner forms six
new bonds and thus offers an elegant and short entry
to complex polyaromatic systems and we believe that
this combination has great potential for further appli-
cations in synthetic chemistry.
˜
EA=10:1)=0.43; IR (ATR): n=3066, 2944, 1691, 1557,
1440, 1072, 1019, 794, 761, 702 cmÀ1 1H NMR (CD2Cl2,
;
600 MHz): d=1.92 (s, 3H), 2.19 (s, 3H), 5.62 (s, 1H), 7.15–
7.19 (m, 4H), 7.24–7.28 (m, 3H), 7.29–7.32 (m, 5H), 7.36 (d,
J
H,H =8.5 Hz, 1H), 7.56 (dt, JH,H =8.5 Hz, JH,H =1.3 Hz, 1H),
9.10 (d, JH,H =8.5 Hz, 1H); 13C NMR (CD2Cl2, 150 MHz):
d=19.8 (q), 20.8 (q), 124.2 (d), 125.0 (d), 125.4 (d), 126.6
(d), 126.7 (s), 127.4 (d), 127.6 (d), 127.9 (d), 128.0 (d, 2C),
128.5 (d, 2C), 129.1 (d), 130.0 (s), 130.5 (d, 2C), 130.8 (d,
2C), 133.5 (s), 133.7 (s), 135.1 (s), 137.6 (s), 138.6 (s), 139.1
(s), 142.2 (s), 143.4 (s), 145.0 (s), 146.8 (s), 195.8 (s); MS
(EI+, 70 eV): m/z (%)=410 (100), 409 (4), 405 (5), 369 (4),
366 (4), 212 (4), 205 (4), 175 (5); HR-MS: m/z=410.1650,
calcd. for C31H22O+: 410.1665 [M+]; UV/VIS (DCM): l (log
e)=251 (4.48), 281 (4.85), 369 (3.65), 384 (3.70), 438 nm
(3.02).
Experimental Section
General Procedure for the Gold Catalysis and the
Photochemical Cyclization
1.00 equiv. of the diyne, 1.50 equiv. of 8-ethylquinoline-1-
oxide and 5 mol% of PPh3AuNTf2 were dissolved in a glass
vial in 600 mL acetonitrile. The solution was stirred at 608C
until TLC showed full conversion. The mixture was trans-
ferred in a 25-mL quartz tube photoreactor with outer cool-
ing jacket. 1.30 equiv. of iodine and 350 equiv. of propylene
oxide were added and the solution was diluted with acetoni-
trile to a volume of 25 mL. Irradiation with a 400 W UV
lamp followed until TLC showed full conversion. The sol-
vent was removed under reduced pressure and the crude
product was recrystallized from acetonitrile.
Acknowledgements
The authors thank Umicore AG & Co. KG for the generous
donation of gold salts.
5,6-Diphenyl-11H-benzo[a]fluoren-11-one (8a): Accord-
ing to the general procedure, 1.00 equiv. of (3-(2-ethynylphe-
nyl)prop-2-yne-1,1,1-triyl)tribenzene (3a, 63.4 mg, 172 mmol)
was dissolved in 600 mL acetonitrile. 1.50 equiv. of 8-ethyl-
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References
Zhang, L. Zhang, J. Am. Chem. Soc. 2010, 132, 3258–
3259; u) A. S. K. Hashmi, M. C. Blanco Jaimes, A. M.
Schuster, F. Rominger, J. Org. Chem. 2012, 77, 6394–
6408.
[1] a) A. S. K. Hashmi, L. Schwarz, J.-H. Choi, T. M. Frost,
Angew. Chem. 2000, 112, 2382–2385; Angew. Chem.
Int. Ed. 2000, 39, 2285–2288; b) A. S. K. Hashmi, T. M.
Frost, J. W. Bats, J. Am. Chem. Soc. 2000, 122, 11553–
11554.
[5] a) L. Ye, Y. Wang, D. H. Aue, L. Zhang, J. Am. Chem.
Soc. 2012, 134, 31–34; b) A. S. K. Hashmi, I. Braun, M.
Rudolph, F. Rominger, Organometallics 2012, 31, 644–
661; c) A. S. K. Hashmi, M. Wieteck, I. Braun, P. Nçsel,
L. Jongbloed, M. Rudolph, F. Rominger, Adv. Synth.
Catal. 2012, 354, 555–562; d) A. S. K. Hashmi, I. Braun,
P. Nçsel, J. Schꢀdlich, M. Wieteck, M. Rudolph, F. Ro-
minger, Angew. Chem. 2012, 124, 4532–4536; Angew.
Chem. Int. Ed. 2012, 51, 4456–4460; e) A. S. K. Hashmi,
M. Wieteck, I. Braun, M. Rudolph, F. Rominger,
Angew. Chem. 2012, 124, 10785–10789; Angew. Chem.
Int. Ed. 2012, 51, 10633–10637; f) M. M. Hansmann, M.
Rudolph, F. Rominger, A. S. K. Hashmi, Angew. Chem.
2013, 125, 2653–2659; Angew. Chem. Int. Ed. 2013, 52,
2593–2598.
[6] a) P. Nçsel, L. N. dos Santos Comprido, T. Lauterbach,
M. Rudolph, F. Rominger, A. S. K. Hashmi, J. Am.
Chem. Soc. 2013, 135, 15662–15666; for other reactions
involving the transfer of a-oxo carbenes derived from
propargylic acetates, see: b) W. Rao, M. J. Koh, D. Li,
H. Hirao, P. W. Chan, J. Am. Chem. Soc. 2013, 135,
7926–7932; c) C. H. Oh, J. H. Kim, L. Piao, J. Yu, S. Y.
Kim, Chem. Eur. J. 2013, 19, 10501–10505; d) T. Lauter-
bach, S. Gatzweiler, P. Nçsel, M. Rudolph, F. Roming-
er, A. S. K. Hashmi, Adv. Synth. Catal. 2013, 355, 2481–
2487; e) T. Lauterbach, M. Ganschow, M. W. Hussong,
M. Rudolph, F. Rominger, A. S. K. Hashmi, Adv.
Synth. Catal. 2014, 356, 680–686.
[2] General reviews: a) G. Dyker, Angew. Chem. 2000,
112, 4407–4409; Angew. Chem. Int. Ed. 2000, 39, 4237–
4239; b) A. S. K. Hashmi, G. Hutchings, Angew. Chem.
2006, 118, 8064–8105; Angew. Chem. Int. Ed. 2006, 45,
7896–7936; c) A. Fꢃrstner, P. W. Davies, Angew. Chem.
2007, 119, 3478–3519; Angew. Chem. Int. Ed. 2007, 46,
3410–3449; d) A. S. K. Hashmi, Chem. Rev. 2007, 107,
3180–3211; e) D. J. Gorin, B. D. Sherry, F. D. Toste,
Chem. Rev. 2008, 108, 3351–3378; f) A. S. K. Hashmi,
Angew. Chem. 2010, 122, 5360–5369; Angew. Chem.
Int. Ed. 2010, 49, 5232–5241; g) M. Rudolph, A. S. K.
Hashmi, Chem. Soc. Rev. 2012, 41, 2448–2462; h) C.
Obradors, A. M. Echavarren, Chem. Commun. 2014,
50, 16–28.
[3] a) G. Li, L. Zhang, Angew. Chem. 2007, 119, 5248–
5251; Angew. Chem. Int. Ed. 2007, 46, 5156–5159;
b) N. D. Shapiro, F. D. Toste, J. Am. Chem. Soc. 2007,
129, 4160–4161.
[4] For reviews on oxidative gold catalysis see: a) L.
Zhang, Acc. Chem. Res. 2014, 47, 877–888; b) H.-S.
Yeom, S. Shin, Acc. Chem. Res. 2014, 47, 966–977; c) J.
Xiao, X. Li, Angew. Chem. 2011, 123, 7364–7375;
Angew. Chem. Int. Ed. 2011, 50, 7226–7236; for select-
ed examples, see: d) Y. Luo, K. Ji, Y.-X. Li, L. Zhang,
J. Am. Chem. Soc. 2012, 134, 17412–17415; e) Y. Wang,
K. Ji, S. Lan, L. Zhang, Angew. Chem. 2012, 124, 1951–
1954; Angew. Chem. Int. Ed. 2012, 51, 1915–1918;
f) A. S. K. Hashmi, T. Wang, S. Shi, M. Rudolph, J.
Org. Chem. 2012, 77, 7761–7767; g) S. Bhunia, S. Ghor-
pade, D. B. Huple, R.-S. Liu, Angew. Chem. 2012, 124,
2993–2996; Angew. Chem. Int. Ed. 2012, 51, 2939–2942;
h) M. Xu, T.-T. Ren, C.-Y. Li, Org. Lett. 2012, 14,
4902–4905; i) R. B. Dateer, K. Pati, R.-S. Liu, Chem.
Commun. 2012, 48, 7200–7202; j) M. Murai, S. Kitaba-
ta, K. Okamoto, K. Ohe, Chem. Commun. 2012, 48,
7622–7624; k) W. Yuan, X. Dong, Y. Wei, M. Shi,
Chem. Eur. J. 2012, 18, 10501–10505; l) W. He, L. Xie,
Y. Xu, J. Xiang, L. Zhang, Org. Biomol. Chem. 2012,
10, 3168–3171; m) D. Qian, J. Zhang, Chem. Commun.
2012, 48, 7082–7084; n) L. Ye, W. He, L. Zhang,
Angew. Chem. 2011, 123, 3294–3297; Angew. Chem. Int.
Ed. 2011, 50, 3236–3239; o) W. He, C. Li, L. Zhang, J.
Am. Chem. Soc. 2011, 133, 8482–8485; p) D. Vasu, H.-
H. Hung, S. Bhunia, S. A. Gawade, A. Das, R.-S. Liu,
Angew. Chem. 2011, 123, 7043–7046; Angew. Chem.
Int. Ed. 2011, 50, 6911–6914; q) D. Qian, J. Zhang,
Chem. Commun. 2011, 47, 11152–11154; r) P. W.
Davies, A. Cremonesi, N. Martin, Chem. Commun.
2011, 47, 379–381; s) L. Ye, W. He, L. Zhang, J. Am.
Chem. Soc. 2010, 132, 8550–8551; t) L. Ye, L. Cui, G.
[7] a) F. B. Mallory, C. S. Wood, J. T. Gordon, L. C. Lind-
quist, M. L. Savitz, J. Am. Chem. Soc. 1962, 84, 4361–
4362; b) F. B. Mallory, C. S. Wood, J. T. Gordon, J. Am.
Chem. Soc. 1964, 86, 3094–3102.
[8] A. S. K. Hashmi, T. Lauterbach, P. Nçsel, M. H. Vil-
helmsen, M. Rudolph, F. Rominger, Chem. Eur. J.
2013, 19, 1058–1065.
[9] CCDC 1022950 (8b) and CCDC 1022951 (13) 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.
[10] a) L. Liu, B. Yang, T. Katz, M. Pointdexter, J. Org.
Chem. 1991, 56, 3769–3775; b) X. Zhang, X. Jiang, K.
Zhang, L. Mao, J. Luo, C. Chi, H. S. O. Chan, J. Wu, J.
Org. Chem. 2010, 75, 8069–8077.
[11] a) T. Navale, K. Thakur, R. Rathore, Org. Lett. 2011,
13, 1634–1637; b) E. Heyer, R. Ziessel, Tetrahedron
Lett. 2013, 54, 3388–3393.
[12] J. F. Briones, H. M. Davies, J. Am. Chem. Soc. 2012,
134, 11916–11919.
[13] G. Henrion, T. E. J. Chavas, X. Le Goff, F. Gagosz,
Angew. Chem. 2013, 125, 6397–6402; Angew. Chem.
Int. Ed. 2013, 52, 6277–6282.
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Oxidative Gold Catalysis Meets Photochemistry – Synthesis
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Adv. Synth. Catal. 2014, 356, 1 – 7
Pascal Nçsel, Setareh Moghimi, Christoph Hendrich,
Marten Haupt, Matthias Rudolph, Frank Rominger,
A. Stephen K. Hashmi*
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