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(4) For an example using a chiral monodentate phosphine
ligand, see: (a) Campbell, M. J.; Toste, F. D. Chem. Sci. 2011, 2, 1369.
For a strategy involving achiral (phosphine)gold(I) complexes in the
presence of chiral counterions:(b) Hamilton, G. L.; Kang, E. J.; Mba, M.;
Toste, F. D. Science 2007, 317, 496.
(5) For general discussions of effects of ligands in gold catalysis, see:
(a) Lopez, S.; Herrero-Gomez, E.; Perez-Galan, P.; Nieto-Oberhuber,
C.; Echavarren, A. M. Angew. Chem., Int. Ed. 2006, 45, 6029. (b) Shapiro,
N. D.; Toste, F. D. J. Am. Chem. Soc. 2007, 129, 4160. (c) Benitez, D.;
Shapiro, N. D.; Tkatchouk, E.; Wang, Y.; Goddard, W. A., III; Toste,
F. D. Nat. Chem. 2009, 1, 482.For reviews, see: (d) Gorin, D. J.; Sherry,
B. D.; Toste, F. D. Chem. Rev. 2008, 108, 3351. (e) Klahn, P.; Kirsch, S. F.
ChemCatChem 2011, 11, 649.
(6) For a review of (N-heterocyclic carbene)gold(I) complexes, see:
Nolan, S. P. Acc. Chem. Res. 2011, 44, 91.
(7) (a) Bartolomꢀe, C.; García-Cuadrado, D.; Ramiro, Z.; Espinet, P.
Inorg. Chem. 2010, 49, 9758. (b) Matsumoto, Y.; Selim, K. B.; Nakanishi,
H.; Yamada, K.; Yamamoto, Y.; Tomioka, K. Tetrahedron Lett. 2010,
51, 404. (c) Wilckens, K.; Lentz, D.; Czekelius, C. Organometallics 2011,
30, 1287. (d) Liu, L.-J.; Wang, F.; Wang, W.; Zhao, M.-X.; Shi, M.
Beilstein J. Org. Chem. 2011, 7, 555. For an example of a (chiral bis-
carbene)gold(I) complex catalyzed hydrogenation giving 95% ee, see:
(e) Arnanz, A.; Gonzꢀalez-Arellano, C.; Juan, A.; Villaverde, G.; Corma,
A.; Iglesias, M.; Sꢀanchez, F. Chem. Commun. 2010, 46, 3001.
(8) For reviews of gold-catalyzed reactions of propargyl esters, see:
(a) Wang, S.; Zhang, G.; Zhang, L. Synlett 2010, 692. (b) Marion, N.;
Nolan, S. P. Angew. Chem., Int. Ed. 2007, 46, 2750.
(9) (a) Gandon, V.; Lemiꢂere, G.; Hours, A.; Fensterbank, L.;
Malacria, M. Angew. Chem., Int. Ed. 2008, 47, 7534. (b) Mauleꢀon, P.;
Krinsky, J. L.; Toste, F. D. J. Am. Chem. Soc. 2009, 131, 4513. (c)
Gonzalez, A. Z.; Benitez, D.; Thatchouk, E.; Goddard, W. A.; Toste,
F. D. J. Am. Chem. Soc. 2011, 133, 5500.
(10) Zhang, Z.; Bender, C. F.; Widenhoefer, R. A. J. Am. Chem. Soc.
2007, 129, 14148.
(11) (a) Parks, J. E.; Balch, A. L. J. Organomet. Chem. 1973, 57, C103.
(b) Bartolomꢀe, C.; Ramiro, Z.; Pꢀerez-Galꢀan, P.; Bour, C.; Raducan, M.;
Echavarren, A. M.; Espinet, P. Inorg. Chem. 2008, 47, 11391. (c) Hashmi,
A. S. K.; Hengst, T.; Lothsch€utz, C.; Rominger, F. Adv. Synth. Catal.
2010, 352, 1315.
(12) Replacing the NaBARF with silver salts in the (phosphine)gold(I)-
catalyzedreactions (Table 1, entries 1 and 2) resulted in diminished yield
and no improvement in enantioselectivity.
(13) Substrates with electron-donating substituents on the propar-
gyl aryl ring could not be prepared or gave poor yields because of
extensive decomposition of starting material. When the propargyl aryl
ring was replaced with a cyclohexyl group, the product mixture consisted
of a 3:1 mixture of benzofuran product (from 5-endo-dig cyclization of
the starting propargyl ester) and the desired chromenyl pivalate.
Substrate 1a with an additional methyl group at the propargylic position
gave desired product in only 11% ee.
(14) Gold-catalyzed reactions terminated by a carbodeauration: (a)
Nakamura, I.; Sato, T.; Yamamoto, Y. Angew. Chem., Int. Ed. 2006,
45, 4473. (b) Dube, P.; Toste, F. D. J. Am. Chem. Soc. 2006, 128, 12062.
(c) Nakamura, I.; Sato, T.; Terada, M.; Yamamoto, Y. Org. Lett. 2008,
10, 2649. (d) Renault, J.; Qian, Z.; Uriac, P.; Gouault, N. Tetrahedron
Lett. 2011, 52, 2476. For a review of reactions of organogold compounds
with electrophiles, see:(e) Hashmi, A. S. K.; Ramamurthi, T. D.; Toss,
M. H.; Tsang, A. S.-K.; Graf, K. Aust. J. Chem. 2010, 63, 1619.
(15) A crossover experiment performed using a 1:1 mixture of 3b
and 3d gave no crossover products, as observed by 1H NMR and HRMS
(ESI). This is consistent with direct intramolecular alkyl migration or
migration via a contact ion pair and is consistent with previous reports.14
(16) The structure and absolute configuration of 4e were determined
by single-crystal X-ray diffraction (see the Supporting Information). The
stereochemistry of the remaining products was assigned by analogy.
(17) The relative configuration was assigned by analogy to trans-2-
phenyl-3-propylchromanone: Saito, A.; Kasai, J.; Odaira, Y.; Fukaya, H.;
Hanzawa, Y. J. Org. Chem. 2009, 74, 5644.
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dx.doi.org/10.1021/ja205068j |J. Am. Chem. Soc. 2011, 133, 12972–12975