D. Miguel, L. Álvarez de Cienfuegos, J. M. Cuerva et al.
SHORT COMMUNICATION
2577–2586; b) S. Sebelius, O. A. Wallner, K. J. Szabó, Org. Lett.
2003, 5, 3065–3068; c) S.-F. Zhu, Y. Yang, L.-X. Wang, B. Liu,
Q.-L. Zhou, Org. Lett. 2005, 7, 2333–2335; Pd- and Sn-based
systems: d) Y. Masuyama, N. Kinugawa, Y. Kurusu, J. Org.
Chem. 1987, 52, 3702–3704; e) W. Qui, Z. Wang, J. Chem. Soc.,
Chem. Commun. 1989, 356–357; SmII-based system: f) T. Tabu-
chi, J. Inanaga, M. Yamaguchi, Tetrahedron Lett. 1986, 27,
1195–1196; Rh-based system: g) M. Vasylyev, H. Alper, J. Org.
Chem. 2010, 75, 2710–2713.
The group of Krische reported new allylations using iridium
complexes and a source of hydrogen, but the procedure seems
to be limited to simple allyl and α-methyl allyl acetate as pronu-
cleophiles and aldehydes as electrophiles: a) I. S. Kim, M.-Y.
Ngai, M. J. Krische, J. Am. Chem. Soc. 2008, 130, 14891–
14899; b) I. S. Kim, M.-Y. Ngai, M. J. Krische, J. Am. Chem.
Soc. 2009, 131, 2514–2520; c) S. B. Han, H. Han, M. J. Krische,
J. Am. Chem. Soc. 2010, 132, 1760–1761; d) Y. J. Zhang, J. H.
Yang, S. H. Kim, M. J. Krische, J. Am. Chem. Soc. 2010, 132,
4562–4563.
For seminal works in titanocene(III) chemistry, see: a) T. V.
Rajan-Babu, W. A. Nugent, J. Am. Chem. Soc. 1994, 116, 986–
997; b) A. Gansäuer, H. Bluhm, M. Pierobon, J. Am. Chem.
Soc. 1998, 120, 12849–12859; for recent reviews, see: c) A. Gan-
säuer, T. Lauterbach, S. Narayan, Angew. Chem. 2003, 115,
5714–5731; Angew. Chem. Int. Ed. 2003, 42, 5556–5573; d) J.
Justicia, L. Álvarez de Cienfuegos, A. G. Campaña, D. Miguel,
V. Jakoby, A. Gänsauer, J. M. Cuerva, Chem. Soc. Rev. 2011,
40, 3525–3537.
a) A. G. Campaña, B. Bazdi, N. Fuentes, R. Robles, J. M.
Cuerva, J. E. Oltra, S. Porcel, A. M. Echavarren, Angew. Chem.
2008, 120, 7625; Angew. Chem. Int. Ed. 2008, 47, 7515–7519;
b) A. Millán, A. G. Campaña, B. Bazdi, D. Miguel, L. Álva-
rez de Cienfuegos, A. M. Echavarren, J. M. Cuerva, Chem. Eur.
J. 2011, 17, 3985–3994; c) A. Millán, L. Álvarez de Cienfuegos,
A. Martín-Lasanta, A. G. Campaña, J. M. Cuerva, Adv. Synth.
Catal. 2011, 353, 73–78; d) A. Millán, A. Martín-Lasanta, D.
Miguel, L. Álvarez de Cienfuegos, J. M. Cuerva, Chem. Com-
mun. 2011, 47, 10470–10472.
Conclusions
In summary, we have demonstrated that the combination
of Ni and Ti catalysts is also a valid method for the efficient
allylation of aldehydes and ketones starting with allyl carb-
onates as pronucleophiles. This protocol is restricted to allyl
donors and therefore useful when acceptors incompatible
with Pd are used. It is worth noting that the reaction takes
place at room temperature and under mild conditions to
give the corresponding homoallylic alcohols in moderate to
good yields. Notably, as far as we know this is the first
example that uses Ni for the catalysis of Barbier-type all-
ylations of simple ketones starting with unactivated allyl
carbonates as pronucleophiles.[20] From a mechanistic point
of view, it seems that TiIII intermediates are involved in the
C–C bond-forming reaction and therefore are responsible
for the enantioselectivity of the process. In this sense, future
work will be conducted to the development of novel chiral
TiIII complexes to allow a full enantioselective version of
this reaction.
[4]
[5]
[6]
Experimental Section
General Procedure for the Ni0/TiIII-Catalyzed Allylation of Carbonyl
Compounds with Carbonates: Rigorously dried and deoxygenated
THF (20 mL) was added to a mixture of Cp2TiCl2 (0.4 mmol),
Ni(PPh3)2Cl2 (0.1 mmol), and Mn dust (8.0 mmol) under an Ar
atmosphere, and the suspension was stirred at room temperature
until it turned dark green (about 5 min). A solution of the carbonyl
compound (1.0 mmol), the allyl carbonate (4.0 mmol), and 2,4,6-
collidine (7.0 mmol) in THF (2 mL) and Me3SiCl (4.0 mmol) were
then added. The mixture was stirred at room temperature for 48 h
and then diluted with EtOAc and washed with 10% aqueous HCl
solution and brine. The organic phase was dried with anhydrous
NaSO4, and the solvent was removed in vacuo. The residue was
purified by flash chromatography (EtOAc/hexane).
[7]
[8]
For a review of the advantages of these mixed systems, see: L.
Ford, U. Jahn, Angew. Chem. 2009, 121, 6504; Angew. Chem.
Int. Ed. 2009, 48, 6386–6389.
a) W. Qiu, Z. Wang, J. Chem. Soc., Chem. Commun. 1989, 356–
357; b) J. P. Takahara, Y. Masuyama, Y. Kurusu, J. Am. Chem.
Soc. 1992, 114, 2577–2586; c) H. Nakamura, N. Asao, Y. Yam-
amoto, J. Chem. Soc., Chem. Commun. 1995, 1273–1274.
Supporting Information (see footnote on the first page of this arti-
cle): Synthesis of the precursors for the allylation reactions, influ-
ence of the pronucleophile in the Ni0/TiIII-promoted allylation of
carbonyl compounds, influence of the chiral phosphorous ligand
(R)-monophos and Ti-Riant catalyst in the enantioselectivity of the
[9]
Other pronucleophiles were tested but with worse results; see
the Supporting Information.
[10]
a) J. Justicia, A. Rosales, E. Buñuel, J. L. Oller-López, M. Val-
divia, A. Haïdour, J. E. Oltra, A. F. Barrero, D. J. Cárdenas,
J. M. Cuerva, Chem. Eur. J. 2004, 10, 1778–1788; b) J. Justicia,
J. L. Oller-Lopez, A. G. Campaña, J. E. Oltra, J. M. Cuerva, E.
Buñuel, D. J. Cardenas, J. Am. Chem. Soc. 2005, 127, 14911–
14921.
allylation of 3-phenylpropanal, general procedures for the Pd0/TiIII
-
and Ni0/TiIII-catalyzed allylation of aldehydes and ketones, charac-
terization data for synthesized compounds, copies of the 1H NMR
and 13C NMR spectra of selected compounds..
[11]
R. E. Estévez, J. Justicia, B. Bazdi, N. Fuentes, M. Paradas, D.
Choquesillo-Lazarte, J. M. García-Ruiz, R. Robles, A. Gan-
säuer, J. M. Cuerva, J. E. Oltra, Chem. Eur. J. 2009, 15, 2774–
2791.
Acknowledgments
We thank the Junta de Andalucía (Project P09-FQM-4571) for fin-
ancial support. A. M. thanks the Ministerio de Ciencia e Innova-
ción (MICINN) for her FPU fellowship. D. M. thanks the Junta
de Andalucía for her postdoctoral contract.
[12]
[13]
[14]
a) A. S. Kende, L. S. Liebeskind, D. M. Braitsch, Tetrahedron
Lett. 1975, 16, 3375–3378; b) M. Zembayashi, K. Tamao, J.
Yoshida, M. Kumada, Tetrahedron Lett. 1977, 18, 4089–4091.
a) G. Schiavon, G. Bontempelli, B. Corrain, J. Chem. Soc., Dal-
ton Trans. 1981, 1074–1981; b) S. Ikeda, K. Suzuki, K. Odash-
ima, Chem. Commun. 2006, 457–459.
A. Bensari, J.-L. Renaud, O. Riant, Org. Lett. 2001, 3, 3863–
3865.
See the Supporting Information for experimental details.
[1] B. M. Rosen, K. W. Quasdorf, D. A. Wilson, N. Zhang, A.-M.
Resmerita, N. K. Garg, V. Percec, Chem. Rev. 2011, 111, 1346–
1416.
[2] J. A. Marshall, Chem. Rev. 2000, 100, 3163–3185.
[3] This goal can be also achieved by using other protocols. For
selected references see: Zn- and B-based systems: a) J. P. Takah-
ara, Y. Masuyama, Y. Kurusu, J. Am. Chem. Soc. 1992, 114,
[15]
[16]
3-Phenylpropanal was chosen as a starting material to make
the detection of the products by HPLC with a UV detector
easier.
1502
www.eurjoc.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 1499–1503