Synthesis of fully substituted 3-formyl-4-iodofurans via a gold(I)-catalyzed oxidation/1,2-alkynyl migration/cyclization/iodination cascade

Article abstract of DOI:10.1002/adsc.201400356

A highly efficient gold(I)-catalyzed cascade reaction for the synthesis of fully substituted 3-formyl-4-iodofurans has been developed. Mechanistic investigations indicate a reaction pathway that involves a direct iodination reaction of the organogold intermediate via functionalization of the Au=C(sp²) bond, instead of a direct iodination of the 3-formylfurans.

Full text of DOI:10.1002/adsc.201400356

UPDATES
DOI: 10.1002/adsc.201400356
Synthesis of Fully Substituted 3-Formyl-4-iodofurans via
a Gold(I)-Catalyzed Oxidation/1,2-Alkynyl Migration/Cyclization/
Iodination Cascade
Tao Wang,+a Shuai Shi,+a Matthias Rudolph,a and A. Stephen K. Hashmia,b,*
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
Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
b
+
These two authors contributed equally to this work.
Received: April 8, 2014; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201400356.
Abstract: A highly efficient gold(I)-catalyzed cas-
cade reaction for the synthesis of fully substituted
3-formyl-4-iodofurans has been developed. Mecha-
nistic investigations indicate a reaction pathway
that involves a direct iodination reaction of the or-
ganogold intermediate via functionalization of the
À
Au CACHTUNGTRENNUNG
(sp2) bond, instead of a direct iodination of
the 3-formylfurans.
Keywords: alkynes; furans; gold; iodine; N-oxides
Scheme 1. Previous work and our hypothesis.
Introduction
Due to their important biological properties furans
are widely found as core structures in natural prod- a novel 1,2-alkynyl migration and a cyclization then
ucts and pharmaceuticals. Additionally, furan deriva- providing furanyl-gold intermediate A. Then A upon
tives can also serve as versatile building blocks in syn- protonation of the Au C
(sp2) bond furnishes the 3-
À
thetic chemistry.[1] A profound usage of furan motives formylfurans 3 (Scheme 1a). A notable observation in
stimulated the development of efficient synthetic related studies is the possibility to functionalize the
(sp2) bond with electrophilic halogen reagents,
À
strategies for this heteroaromatic ring. It was reported Au C
that slight changes in the substitution pattern at the such as NIS (N-iodosuccinimide) and related com-
furan nucleus cause significant differences in their pounds.[6] Based on these studies, we envisioned that
biological activities.[2] Thus efficient methods for the the furanyl-gold intermediate A could also be trapped
synthesis of highly functionalized/substituted furans to by electrophilic halogens giving 3-formyl-4-halofurans
further enhance their use by making them available as products (Scheme 1b). With the additional halogen
are continually desired.
functionality besides the formyl moiety, these furans
Very recently, inspired by the recent developments are expected to be versatile synthetic intermediates.[7]
in the field of a-oxo gold carbenoids,[3,4] our group de- However, to the best of our knowledge, only one
veloped an efficient cascade reaction for the synthesis practical and flexible method is currently available
of highly substituted 3-formyl furans from easily ac- for the access of such compounds, applying a two-
cessible 1,4-diyn-3-ols 1 (Scheme 1a).[5] The reaction step, semi-one-pot protocol.[8] Herein, as part of our
is initiated by a nucleophilic attack of a pyridine N- efforts on the synthesis of polysubstituted furans,[9] we
oxide at the gold(I)-activated alkyne, followed by report a highly efficient and easy gold(I)-catalyzed
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Table 1. Optimization of the reaction conditions.[a]
Entry
Catalyst (3 mol%)
2 (1.2 equiv.)
Solvent/Temperature/Time
Yield [%][b]
1
2
3
4
5
6
7
8
IPrAuCl/AgOTf
IPrAuCl/AgOTf
IPrAuCl/AgOTf
IPrAuCl/AgOTf
IPrAuCl/AgOTf
Ph3PAuCl/AgOTf
AuCl3
PtCl2
AuCl
AgOTf
IPrAuCl/AgNTf2
IPrAuCl/AgSbF6
IPrAuCl/AgBF4
IPrAuCl/AgSbF6
IPrAuCl/AgSbF6
IPrAuCl/AgSbF6
–
2a
2b
2c
2d
2e
2a
2a
2a
2a
2a
2a
2a
2a
2a
2a
2a
2a
2a
DCM/r.t./1 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./2 h
DCM/r.t./1 h
DCM/r.t./1 h
DCM/r.t./2 h
toluene/r.t./1 h
CH3CN/r.t./2 h
DCE/r.t./2 h
toluene/r.t./2 h
toluene/r.t./1 h
72
40 (46)
45 (30)
56 (28)
63 (19)
trace[c]
trace[c]
–
9
trace[c]
–
73
75
45 (45)
80
30 (55)
63 (20)
–
10
11
12
13
14
15
16
17
18[d]
IPrAuCl/AgSbF6
16
[a]
All reactions were carried out on 0.2 mmol scale in 1 mL of solvent.
Isolated yield, the number in the parentheses is recovered 1a after column chromatography.
Decomposition of 1a was observed.
[b]
[c]
[d]
1.2 equivalents of I2 were added instead of NIS.
cascade reaction for the preparation of 3-formyl-4-io- served without gold as catalyst (entry 17). When I2
dofurans 4 from easily accessible starting materials.
was used instead of NIS, 4a was only obtained in low
yield (entry 18).
With these optimized conditions we next explored
the substrate scope of the reaction (Table 2 and
Table 3). Symmetrical starting materials were exam-
Results and Discussion
To prove this hypothesis, a mixture of 1,4-diyn-3-ol ined first and the results are summarized in Table 2.
1a, 3,5-dichloropyridine N-oxide 2a and NIS in di- In analogy to the synthesis of 3-formylfurans,[5] sub-
chloromethane was treated with IPrAuCl/AgOTf at strates with substituents in the para-position of the
room temperature. Pleasingly, the reaction worked phenyl group smoothly delivered 3-formyl-4-iodofur-
smoothly and afforded the desired 3-formyl-4-iodofur- an 4 in good yields (4b–4e). Substrates bearing elec-
an 4a in good yield (Table 1, entry 1). Encouraged by tron-donating groups usually gave better yields of the
this, we further optimized the reaction conditions corresponding products (4b and 4c) than those with
(Table 1). At first a variety of pyridine N-oxides was electron-withdrawing groups (4d and 4e). The reac-
tested but no improvement was achieved (entries 2– tions worked also well for meta-substituted phenyl
5). A subsequent catalyst screening revealed that nei- substrates, affording the corresponding furans 4 in
ther PtCl2 (entry 8) nor AgOTf (entry 10) can cata- good yields (4f and 4g). A heteroaromatic substrate
lyze this reaction, while Ph3PAuCl/AgOTf, AuCl3 and and an aliphatic diyne starting material were also in-
AuCl just gave trace amounts of 4a (entries 6, 7 and vestigated, leading to the corresponding 3-formyl-4-
9). Different silver salts were then tested in combina- iodofurans in good and moderate yields, respectively
tion with IPrAuCl (entries 11–13), among which (4h and 4i). NBS turned out to be a suitable electro-
AgSbF6 gave the best result (entry 12). A solvent philic halogen reagent as well. The corresponding re-
screening revealed that toluene is the best solvent for action gave 3-formyl-4-bromofuran 5a in 71% yield,
this transformation (entry 14). No product was ob-
2
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Synthesis of Fully Substituted 3-Formyl-4-iodofurans
Table 2. Scope of the reaction for symmetrical starting materials 1.[a]
[a]
Reaction conditions: NXS (0.36 mmol) and 2a (0.36 mmol, 59 mg) were added to a suspension of IPrAuCl (9 mmol,
5.6 mg) and AgSbF6 (9 mmol, 3.1 mg) in toluene (1.5 mL). Then 1 (0.3 mmol) was added and the mixture was allowed to
stir at room temperature for 2 h.
Reaction time: 12 h.
[b]
Table 3. Scope of the reaction for unsymmetrical starting materials 1.[a]
[a]
Reaction conditions: NIS (0.36 mmol) and 2a (0.36 mmol, 59 mg) were added to a suspension of IPrAuCl (9 mmol,
5.6 mg) and AgSbF6 (9 mmol, 3.1 mg) in toluene (1.5 mL). Then 1 (0.3 mmol) was added and the mixture was allowed to
stir at room temperature for 2 h.
Reaction time: 12 h.
5 mol% of catalysts were used.
[b]
[c]
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accompanied by 9% of 3-formylfuran 3a as a by-prod- [Eq. (1)]. This clearly shows that furan-gold inter-
uct. mediate A (Scheme 1) is directly iodinated by NIS. A
The results for unsymmetrical starting materials are gold-catalyzed iodination after the formation of an in-
summarized in Table 3. Substrate 1j bearing a phenyl termediate 3-formylfuran can be ruled out in this
group and a 4-methoxyphenyl group, afforded 4j and case.
4j’ in a nearly 8:1 ratio under standard conditions.
Being versatile synthetic building blocks, 3-formyl-
Furan 4j in which the electron-rich 4-methoxyphenyl 4-iodofurans can, for example, easily be transferred to
group is placed at the 2-position of the 3-formyl-4-io- other fully substituted furans. For example, 4a could
dofuran turned out to be the major product. We be converted to 3-formylfurans 6 and 7 in good yields
assume that this product is favored due to that a pre- via Sonogashira and Suzuki coupling reactions, re-
ferred coordination of the cationic gold-fragment spectively [Eq. (2) and Eq. (3)].
onto the more electron-rich alkyne system, which fa-
cilitates the nucleophilic attack by the pyridine N-
oxide. To prove this hypothesis 1k was prepared, Conclusions
which indeed afforded 4k[10] as a single regioisomer.
Sterically demanding groups can also be used to In conclusion, we have developed an efficient gold(I)-
induce high selectivity. Thus, 4l was obtained as single catalyzed cascade reaction providing 3-formyl-4-iodo-
regioisomer from substrate 1l bearing a bulky aromat- furans from easily accessible starting materials. This
ic group besides a phenyl group. The same strategy opens an efficient and experimentally simple route
was applied with substrate 1m bearing a TIPS (triiso- for the synthesis of 3-formyl-4-iodofurans, compounds
propylsilyl) group in addition to the phenyl group: 1m that can serve as useful synthetic building blocks. A
afforded 4m in moderate yield as a single regioisomer. mechanistic investigation revealed that the reaction
Furthermore, 4n containing one aliphatic group and pathway involves a direct iodination reaction of the
one aromatic group, 4o bearing two different aliphatic Au CACTHNUTRGNEUNG
(sp2) bond instead of an iodination of an inter-
À
groups, and 4p bearing an ether group could all be mediate 3-formylfuran.
obtained as single regioisomers. A terminal alkyne
was also tolerated which could be demonstrated by
compound 4q that was obtained as a single product in Experimental Section
moderate yield.
(sp2) bonds can react General Procedure for Gold(I)-Catalyzed Cascade
À
Besides the reports that Au C
with electrophilic halogens leading to the halogenated Reactions
products, a direct halogenation of aromatic com-
pounds by N-halosuccinimides in gold catalysis is also
documented in the literature.[6k,l] To investigate the
mechanism, NIS was added in one pot after the com-
plete conversion of 1a to 3a. No 3-formyl-4-iodofuran
4a was formed even after a prolonged reaction time
NXS (0.36 mmol) and 2a (59 mg, 0.36 mmol) were added
to a stirred suspension of IPrAuCl (5.6 mg, 9 mmol) and
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Synthesis of Fully Substituted 3-Formyl-4-iodofurans
AgSbF6 (3.1 mg, 9 mmol) in 1.5 mL of toluene. After that
1 (0.3 mmol) was added and the resulting mixture was al-
lowed to stir at room temperature for 2 h. After that the sol-
vent was removed and the crude product was purified via
column chromatography on silica gel (petroleum ether/ethyl
acetate, 20:1 to 10:1) to yield corresponding products in
moderate to good yields.
Acknowledgements
The authors thank Umicore AG & Co. KG for the generous
donation of gold salts. T. Wang and S. Shi are grateful for the
fellowships from China Scholarship Council (CSC).
4-Iodo-2,5-diphenylfuran-3-carbaldehyde (4a):[8] Yield:
1
References
80%; H NMR (300 MHz, CDCl3): d=10.09 (s, 1H), 8.08–
8.05 (m, 2H), 7.92–7.86 (m, 2H), 7.55–7.43 (m, 6H).
[1] a) B. H. Lipshutz, Chem. Rev. 1986, 86, 795–819;
b) X. L. Hou, Z. Yang, H. N. C. Wong, in: Progress in
Heterocyclic Chemistry, (Eds.: G. W. Gribble, T. L. Gil-
christ), Pergamon, Oxford, 2003, vol. 15, pp 167–205;
c) D. M. X. Donnelly, M. J. Meegan, in: Comprehensive
Heterocyclic Chemistry, (Eds.: A. R. Katritzky, C. W.
Rees), Pergamon, Oxford, 1984, vol. 4, pp 657–712.
[2] V. Anupam, S. N. Pandeya, S. Shweta, Int. J. Res. Ayur-
veda Pharm. 2011, 2, 1110–1116.
[3] Examples for the generation and transformations of a-
oxo gold carbenoids from sulfoxides and alkynes, see:
a) J. Xiao, X. Li, Angew. Chem. 2011, 123, 7364–7375;
Angew. Chem. Int. Ed. 2011, 50, 7226–7236; b) N. D.
Shapiro, F. D. Toste, J. Am. Chem. Soc. 2007, 129,
4160–4161; c) G. Li, L. Zhang, Angew. Chem. 2007,
119, 5248–5251; Angew. Chem. Int. Ed. 2007, 46, 5156–
5159; d) C.-W. Li, K. Pati, G.-Y. Lin, S. M. Abu Sohel,
H.-H. Hung, R.-S. Liu, Angew. Chem. 2010, 122,
10087–10090; Angew. Chem. Int. Ed. 2010, 49, 9891–
9894; e) N. Marion, S. P. Nolan, Chem. Soc. Rev. 2008,
37, 1776–1782; f) P. W. Davies, S. J.-C. Albrecht,
Angew. Chem. 2009, 121, 8522–8525; Angew. Chem.
Int. Ed. 2009, 48, 8372–8375; g) A. B. Cuenca, S. Mon-
tserrai, K. M. Hossain, G. Mancha, A. Lledꢂs, M.
Medio-Simꢂn, G. Ujaque, G. Asensio, Org. Lett. 2009,
11, 4906–4909; h) C.-F. Xu, M. Xu, Y.-X. Jia, C.-Y. Li,
Org. Lett. 2011, 13, 1556–1559.
4-Iodo-2,5-di-para-tolylfuran-3-carbaldehyde (4b): Yield:
80%; yellow solid; mp 140–1418C; 1H NMR (300 MHz,
CD2Cl2): d=10.04 (s, 1H), 7.94 (d, 2H, J=8.3 Hz), 7.78 (d,
2H, J=8.3 Hz), 7.35–7.29 (m, 4H), 2.44 (s, 3H), 2.42 (s,
3H); 13C NMR (75 MHz, CD2Cl2): d=186.9 (d), 161.6 (s),
152.9 (s), 141.8 (s), 140.0 (s), 130.1 (d), 129.7 (d), 128.8 (d),
127.6 (d), 126.9 (s), 125.9 (s), 121.8 (s), 61.3 (s), 21.8 (q),
˜
21.7 (q); IR (ATR): n=3021, 2916, 2869, 2796, 1677, 1606,
1570, 1541, 1492, 1409, 1376, 1337, 1316, 1290, 1253, 1185,
1115, 1085, 1033, 1017, 945, 883, 814, 777, 719, 709, 683, 659,
640 cmÀ1
; HR-MS (EI): m/z=402.0128, calculated for
C19H15IO2 [M]+: 402.0117.
4-Bromo-2,5-diphenylfuran-3-carbaldehyde (5a): Yield:
71%; yellow solid; mp 75–768C; 1H NMR (300 MHz,
CD2Cl2): d=10.11 (s, 1H), 8.09–8.05 (m, 2H), 7.96–7.93 (m,
2H), 7.56–7.40 (m, 6H); 13C NMR (75 MHz, CD2Cl2): d=
185.9 (d), 160.0 (s), 149.6 (s), 131.3 (d), 129.6 (d), 129.4 (d),
129.2 (d), 129.1 (s), 128.8 (d), 128.7 (s), 126.7 (d), 121.4 (s),
˜
97.2 (s); IR (ATR): n=3058, 2865, 2794, 2757, 1736, 1688,
1600, 1580, 1562, 1537, 1482, 1443, 1422, 1346, 1316, 1292,
1262, 1187, 1171, 1153, 1100, 1072, 1044, 1031, 1022, 998,
949, 914, 889, 837, 783, 768, 760, 735, 687, 671, 661,
618 cmÀ1
; HR-MS (EI): m/z=325.9958, calculated for
C17H11BrO2 [M]+: 325.9942.
2,5-Diphenyl-4-(phenylethynyl)furan-3-carbaldehyde
(6)
[4] Examples for the generation and transformation of a-
oxo gold carbenoids from nitrogen oxides and alkynes,
see: a) L. Wang, X. Xie, Y. Liu, Angew. Chem. 2013,
125, 13544–13548; Angew. Chem. Int. Ed. 2013, 52,
13302–13306; b) W. Yuan, X. Dong, Y. Wei, M. Shi,
Chem. Eur. J. 2012, 18, 10501–10505; c) L. Ye, L. Cui,
G. Zhang, L. Zhang, J. Am. Chem. Soc. 2010, 132,
3258–3259; d) B. Lu, C. Li, L. Zhang, J. Am. Chem.
Soc. 2010, 132, 14070–14072; e) 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; f) A. Mukherjee, R. B. Dateer, R.
Chaudhuri, S. Bhunia, S. N. Karad, R.-S. Liu, J. Am.
Chem. Soc. 2011, 133, 15372–15375; g) H.-S. Yeom, J.-
E. Lee, S. Shin, Angew. Chem. 2008, 120, 7148–7151;
Angew. Chem. Int. Ed. 2008, 47, 7040–7043; h) G. Hen-
rion, T. E. J. Chavas, X. L. Goff, F. Gagosz, Angew.
Chem. 2013, 125, 6397–6402; Angew. Chem. Int. Ed.
2013, 52, 6277–6282; i) J. Fu, H. Shang, Z. Wang, L.
Chang, W. Shao, Z. Yang, Y. Tang, Angew. Chem. 2013,
125, 4292–4296; Angew. Chem. Int. Ed. 2013, 52, 4198–
4202; j) S. Kramer, T. Skrydstrup, Angew. Chem. 2012,
124, 4759–4762; Angew. Chem. Int. Ed. 2012, 51, 4681–
4684; k) D. Qian, J. Zhang, Chem. Commun. 2012, 48,
7082–7084; l) D. Garayalde, C. Nevado, ACS Catal.
2012, 2, 1462–1479; m) M. Murai, S. Kitabata, K. Oka-
PdACHTUNGTRENNUNG(Ph3P)2Cl2 (4.2 mg, 6 mmol) and CuI (2.3 mg,12 mmol)
were added to a stirring solution of phenylacetylene (31 mg,
0.3 mmol) and 4a (75 mg, 0.2 mmol) in 2 mL of solvent
(THF/NEt3 =2:1) under N2. The resulting solution was then
refluxed under N2 for 2 h. After that the solvent was re-
moved and the crude product was purified via column chro-
matography on silica gel (petroleum ether/ethyl acetate,
10:1) to give 6 as a yellow solid; yield: 55 mg (79%); mp
1
150–1518C; H NMR (500 MHz, CD2Cl2): d=10.27 (s, 1H),
8.26–8.24 (m, 2H), 8.07–8.04 (m, 2H), 7.64–7.62 (m, 2H),
7.57–7.50 (m, 5H), 7.45–7.41 (m, 4H); 13C NMR (125 MHz,
CD2Cl2): d=185.9 (d), 158.6 (s), 154.9 (s), 132.0 (d), 131.2
(d), 129.8 (s), 129.7 (d), 129.39 (d), 129.37 (d), 129.36 (d),
129.1 (d), 129.0 (s), 128.7 (d), 125.8 (d), 123.4 (s), 123.2 (s),
˜
104.5 (s), 97.7 (s), 80.9 (s); IR (ATR): n=3053, 2856, 2818,
2763, 1973, 1746, 1686, 1602, 1579, 1542, 1481, 1442, 1421,
1334, 1314, 1290, 1223, 1189, 1165, 1153, 1120, 1099, 1070,
1028, 999, 971, 926, 834, 781, 760, 745, 686, 650, 617 cmÀ1
;
HR-MS (EI): m/z=348.1151, calculated for C25H16O2 [M]+:
348.1150.
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UPDATES
Tao Wang et al.
moto, K. Ohe, Chem. Commun. 2012, 48, 7622–7624;
Yan, D. Qiu, F. Li, Y. Zhang, J. Wang, Angew. Chem.
2010, 122, 2072–2076; Angew. Chem. Int. Ed. 2010, 49,
2028–2032; l) D. Qiu, F. Mo, Z. Zheng, Y. Zhang, J.
Wang, Org. Lett. 2010, 12, 5474–5477; m) P. Nçsel, T.
Lauterbach, M. Rudolph, F. Rominger, A. S. K.
Hashmi, Chem. Eur. J. 2013, 19, 8634–8641; n) A. S. K.
Hashmi, T. D. Ramamurthi, M. H. Todd, A. S.-K.
Tsang, K. Graf, Aust. J. Chem. 2010, 63, 1619–1626.
[7] T. Lampe, R. Kast, F. Stoll, J. Schuhmacher, PCT Int.
Patent Appl. WO 2009/097991, 2009.
n) A. S. K. Hashmi, T. Wang, S. Shi, M. Rudolph, J.
Org. Chem. 2012, 77, 7761–7767; o) P. Nçsel, L. N. S.
Comprido, T. Lauterbach, M. Rudolph, F. Rominger,
A. S. K. Hashmi, J. Am. Chem. Soc. 2013, 135, 15662–
15666.
[5] T. Wang, S. Shi, M. M. Hansmann, E. Rettenmeier, M.
Rudolph, A. S. K. Hashmi, Angew. Chem. 2014, 126,
3789–3793; Angew. Chem. Int. Ed. 2014, 53, 3715–3719.
[6] a) A. S. K. Hashmi, T. D. Ramamurthi, F. Rominger, J.
Organomet. Chem. 2009, 694, 592–597; b) A. Buzas, F.
Gagosz, Org. Lett. 2006, 8, 515–518; c) A. Buzas, F. Is-
trate, F. Gagosz, Org. Lett. 2006, 8, 1957–1959; d) S. F.
Kirsch, J. T. Binder, B. Crone, A. Duschek, T. T. Haug,
C. Liꢃbert, H. Menz, Angew. Chem. 2007, 119, 2360–
2363; Angew. Chem. Int. Ed. 2007, 46, 2310–2313;
e) M. Yu, G. Zhang, L. Zhang, Org. Lett. 2007, 9, 2147–
2150; f) M. Yu, G. Zhang, L. Zhang, Tetrahedron 2009,
65, 1846–1855; g) P. Kothandaraman, S. R. Mothe,
S. S. M. Toh, P. W. H. Chan, J. Org. Chem. 2011, 76,
7633–7640; h) K. H. Nguyen, S. Tomasi, M. L. Roch, L.
Toupet, J. Renault, P. Uriac, N. Gouault, J. Org. Chem.
2013, 78, 7809–7815; i) Z. Shi, C. He, J. Am. Chem. Soc.
2004, 126, 13596–13597; j) J. Oliver-Meseguer, J. R.
Cabrero-Antonino, I. Domꢄnguez, A. Leyva-Pꢃrez, A.
Corma, Science 2012, 338, 1452–1455; k) F. Mo, J. M.
[8] G. Raffa, G. Balme, N. Monteiro, Eur. J. Org. Chem.
2013, 105–110.
[9] a) A. S. K. Hashmi, L. Schwarz, Chem. Ber./Recl. 1997,
130, 1449–1456; b) A. S. K. Hashmi, P. Sinha, Adv.
Synth. Catal. 2004, 346, 432–438; c) 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; d) A. S. K. Hashmi, T. Hꢀffner, M. Rudolph, F.
Rominger, Eur. J. Org. Chem. 2011, 667–671; e) T.
Wang, S. Shi, M. H. Vilhelmsen, T. Zhang, M. Rudolph,
F. Rominger, A. S. K. Hashmi, Chem. Eur. J. 2013, 19,
12512–12516.
1
[10] The products 4k–4p were confirmed by H-1H NOESY
spectra, for details please see the Supporting Informa-
tion.
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asc.wiley-vch.de
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
These are not the final page numbers!

UPDATES
Synthesis of Fully Substituted 3-Formyl-4-iodofurans via
a Gold(I)-Catalyzed Oxidation/1,2-Alkynyl Migration/
Cyclization/Iodination Cascade
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Adv. Synth. Catal. 2014, 356, 1 – 7
Tao Wang, Shuai Shi, Matthias Rudolph,
A. Stephen K. Hashmi*
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
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ÞÞ
These are not the final page numbers!