Organic Letters
Letter
T. D.; Adduci, L. L.; Gagne,
́
M. R. Angew. Chem., Int. Ed. 2012, 51, 2452.
Notes
(d) Zhdanko, A.; Maier, M. E. Chem.Eur. J. 2014, 20, 1918.
The authors declare no competing financial interest.
(e) Hashmi, A. S. K.; Braun, I.; Nosel, P.; Schadlich, J.; Wietek, M.;
̈
̈
Rudolph, M.; Rominger, F. Angew. Chem., Int. Ed. 2012, 51, 4456.
(f) Hansmann, M. M.; Rudolph, M.; Rominger, F.; Hashmi, A. S. K.
Angew. Chem., Int. Ed. 2013, 52, 2593.
(11) For some gold-catalyzed hydroarylations which are facilitated by
additional Tf2NH, see: Shu, C.; Li, L.; Chen, C.-B.; Shen, H.-C.; Ye, L.-
W. Chem. Asian. J. 2014, 9, 1525.
(12) For our contribution in Tf2NH-catalyzed Friedel−Crafts-type α-
amidoalkylation reactions, see: (a) Devineau, A.; Pousse, G.; Taillier, C.;
Rouden, J.; Blanchet, J.; Dalla, V. Adv. Synth. Catal. 2010, 352, 2881.
(b) Moussa, S.; Comesse, S.; Dalla, V.; Daïch, A.; Netchitaïlo, P. Synlett
2011, 2425.
(13) A preliminary catalyst screening, notably using CAT.4, was
undertaken and did not allow significant performance of the reaction;
see footnote d in Scheme 1.
(14) The successful use of thiophene derivatives in hydroarylation is
quite rare. (a) See ref 7e for a single example with moderate yield. (b)
For unsuccessful attempts, see: Kumar, A.; Vachhani, D. D.; Modha, S.
G.; Sharma, S. K.; Parmar, V. S.; van der Eycken, E. V. Synthesis 2013,
2571.
(15) Bulky N-silyl pyrroles were chosen for their ability to direct total
meta selectivity in the Friedel−Crafts amidoalkylation, a feature not
shared by pyrrole or N-Me-pyrrole. For a review discussing these
properties of the commercially available N-TIPS-pyrrole, see: Jolicoeur,
B.; Chapman, E. E.; Thompson, A.; Lubell, W. D. Tetrahedron 2006, 62,
11531.
ACKNOWLEDGMENTS
L.B. thanks the “Region Haute-Normandie” and “the Res
CRUNCH Orga” for a grant and financial support. M.S.A. is
grateful to the Tunisian government for a scholarship and to
AUF for financial support.
■
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eau
REFERENCES
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(17) The gold-catalyzed hydroarylation of internal alkylalkynes is well
documented, and its regioselectivity 6-exo versus 7-endo varies
substantially as a function of the topology of the substrate. For examples
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(5) Boiaryna, L.; El Mkaddem, M. K.; Taillier, C.; Dalla, V.; Othman,
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X.-Y.; Che, C.-M. Org. Lett. 2009, 11, 4204.
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gold(I) complexes were applied in the hydroarylation of terminal
alkynes follow an exclusive 6-exo selectivity: (a) Ferrer, C.; Amijs, C. H.
M.; Echavarren, A. M. Chem.Eur. J. 2007, 13, 1358. (b) Lu, Y.; Du, X.;
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3631. (h) A single report by Gagosz and colleagues describes
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fromterminal alkynes in addition to the usual 6-exo products: (i) Jurberg,
I. D.; Gagosz, F. J. Organomet. Chem. 2011, 696, 37.
(8) Every cascade reaction we have examined proceeded with identical
regiocontrol as the accordant hydroarylation executed from the isolated
F−C product 3. Details on the results of these hydroarylations, as well as
on the formation of side products formed in the cascade reactions, are
given in the Supporting Information.
(9) Although the overall nucleophilicity of 1,3-dimethoxybenzene is
estimated to be greater than that of indole and 2-methylthiophene, the
sluggish reactivity exhibited by 3d could be attributed to the low local
nucleophilicity of the carbon atom (with a red label in Table 1) to attack
the alkyne−gold complex: Pratihar, S.; Roy, S. J. Org. Chem. 2010, 75,
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Furstner, A. Angew. Chem., Int. Ed. 2010, 49, 8466. (c) Weber, D.; Jones,
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M. R.
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