7 Intermolecular allyl–allyl cross-couplings with stoichiometric Pd
complexes: Mg: (a) A. Goliaszewski and J. Schwartz, J. Am. Chem.
Soc., 1984, 106, 5028; (b) A. Goliaszewski and J. Schwartz, Tetra-
hedron, 1985, 41, 5779; Si: (c) A. Goliaszewski and J. Schwartz,
Organometallics, 1985, 4, 417.
8 Intermolecular allyl–allyl cross-couplings with halides, acetates,
and carbonates: Sn: (a) B. M. Trost and E. Keinan, Tetrahedron
Lett., 1980, 21, 2595; (b) J. Godschalx and J. K. Stille, Tetrahedron
Lett., 1980, 21, 2599; (c) H. Nakamura, M. Bao and
Y. Yamamoto, Angew. Chem., Int. Ed., 2001, 40, 3208; In:
(d) P. H. Lee, S.-y. Sung, K. Lee and S. Chang, Synlett, 2002,
146; (e) P. H. Lee, E. Shim, K. Lee, D. Seomoon and S. Kim, Bull.
Korean Chem. Soc., 2005, 26, 157.
9 Intermolecular allyl–allyl cross-couplings with ethers: Si:
M. Murakami, T. Kato and T. Mukaiyama, Chem. Lett., 1987, 1167.
10 E. Ferrer Flegeau, U. Schneider and S. Kobayashi, Chem.–Eur. J.,
2009, 15, 12247.
11 Observation of symmetrical 1,5-dienes as coupling by-products
under Pd catalysis: (a) T. Ishiyama, T.-a. Ahiko and
N. Miyaura, Tetrahedron Lett., 1996, 37, 6889; (b) M. Kimura,
I. Kiyama, T. Tomizawa, Y. Horino, S. Tanaka and Y. Tamaru,
Tetrahedron Lett., 1999, 40, 6795.
Scheme 3 Proposed mechanism for linear-g-selective cross-coupling.
dual activation of allyl alcohols with the nickel catalyst and the
boronate reagent to generate p-allyl–nickel species as common
reaction intermediates (oxidative addition; Scheme 3). Allyl–allyl
cross-coupling would subsequently occur between the two
sterically least congested carbon atoms of the electrophilic
p-allyl–nickel and the nucleophilic allyl borate reagents. Thus,
we favor a nontransmetalative pathway based on the observed
excellent linear-g-selectivity with 6. However, we cannot exclude
a 1,10-reductive elimination of a generated bis(Z1-allyl)–nickel
intermediate,14 or similar transmetalative pathways.22
12 Catalytic activation of allyl boronates for addition to C(sp2)
centers: selected examples for 1,2-addition: (a) account:
D. G. Hall, Synlett, 2007, 1644; (b) P. Zhang and J. P. Morken,
J. Am. Chem. Soc., 2009, 131, 12550; (c) P. Jain and J. C. Antilla,
J. Am. Chem. Soc., 2010, 132, 11884 and references cited therein;
1,4-addition: (d) J. D. Sieber, S. Liu and J. P. Morken, J. Am.
Chem. Soc., 2007, 129, 2214; (e) J. D. Sieber and J. P. Morken,
J. Am. Chem. Soc., 2008, 130, 4978; (f) M. B. Shaghafi, B. L. Kohn
and E. R. Jarvo, Org. Lett., 2008, 10, 4743.
In summary, we have demonstrated nickel-catalysed inter-
molecular allyl–allyl cross-couplings between alcohols and
boronates, and report here the first general use of allyl alcohols
in this context.21 The key to this facile C–O bond activation is
the use of moderately Lewis acidic boron-based reagents
combined with an appropriate nickel(0)–phosphine catalyst
(dual activation).19 The reactions proceeded under mild
conditions with excellent linear- and g-selectivity. This new
protocol is applicable to the selective preparation of vinyl
silanes,23 and should therefore find great interest in organic
chemistry. Further synthetic and mechanistic investigations
are currently underway in our laboratories.
13 Catalytic C(sp3)–C(sp3) cross-couplings between O,O-acetals and
allyl boronates: U. Schneider, H. T. Dao and S. Kobayashi, Org.
Lett., 2010, 12, 2488.
14 While our present alcohol study was in progress, Pd-catalysed
branched-selective allyl–allyl cross-couplings between carbonates
and boronates were reported: P. Zhang, L. A. Brozek and
J. P. Morken, J. Am. Chem. Soc., 2010, 132, 10686.
15 Catalytic activation of allyl alcohols for intermolecular C–C bond
formation: R. Matsubara, K. Masuda, J. Nakano and
S. Kobayashi, Chem. Commun., 2010, 46, 8662 and references cited
therein.
Notes and references
1 (a) Transition Metal Reagents and Catalysts: Innovations in
Organic Synthesis, ed. J. Tsuji, Wiley, Chichester, 2000;
(b) Catalytic Asymmetric Catalysis, ed. I. Ojima, Wiley-VCH,
Weinheim, 2000.
16 Catalysts that did not promote any reaction between 1a and 2a
(recovery of starting materials): AuHal3 (Hal = Cl, Br), XAuCl4ꢀ
yH2O (X = H, Na; y = 2, 3), FeCl3, Me3SiOTf, B(C6F5)3,
MeO-9-BBN, InCl3.
2 Review: D. J. Cardenas, Angew. Chem., Int. Ed., 2003, 42, 384.
´
3 (a) Terpenes—Flavors, Fragrances, Pharmaca, Pheromones, ed.
E. Breitmaier, Wiley-VCH, Weinheim, 2006; (b) K. C. Nicolaou
and T. Montagnon, in Molecules that Changed the World,
Wiley-VCH, Weinheim, 2008.
4 Selected examples for the use of 1,5-dienes in organic synthesis:
(a) L. E. Overman and F. M. Knoll, J. Am. Chem. Soc., 1980,
102, 865; (b) R. C. D. Brown and J. F. Keily, Angew. Chem., Int.
Ed., 2001, 40, 4496; (c) H. Nakamura and Y. Yamamoto, in
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ed. E.-i. Negishi and A. de Meijere, Wiley-Interscience, West
Lafayette, 2002, vol. 2, p. 2919; (d) T. J. Donohoe and
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(e) Y.-J. Zhao, S.-S. Chng and T.-P. Loh, J. Am. Chem. Soc.,
17 Catalytic C(sp3)–C(sp3) cross-coupling between ethers and allyl
borane 2b: H. T. Dao, U. Schneider and S. Kobayashi, Chem.
Commun., 2011, 47, 692.
18 Conversion of allyl alcohols into allyl indium reagents with
Ni(acac)2 (5–20 mol%), PPh3 (20–80 mol%) and InI (100
mol%): T. Hirashita, S. Kambe, H. Tsuji, H. Omori and
S. Araki, J. Org. Chem., 2004, 69, 5054.
19 During the preparation of our manuscript, related studies for the
catalytic activation of allyl alcohols were reported: (a) Pd-catalysed
intermolecular C–Si and C–B bond formations: N. Selander,
J. R. Paasch and K. J. Szabo, J. Am. Chem. Soc., 2011, 133, 409;
´
Pd-catalysed intermolecular C–C bond formations: (b) S.-F. Zhu,
X.-C. Qiao, Y.-Z. Zhang, L.-X. Wang and Q.-L. Zhou, Chem. Sci.,
2011, 2, 1135; (c) boronic acid-catalysed intramolecular C–O bond
formations: H. Zheng, M. Lejkowski and D. G. Hall, Chem. Sci.,
2011, 2, 1305.
2007, 129, 492; (f) J. A. Feducia and M. R. Gagne
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(a) B. M. Trost and K. M. Pietrusiewicz, Tetrahedron Lett.,
20 Pd(0)-catalysed Cope-type rearrangement of 1,5-dienes:
H. Nakamura, H. Iwama, M. Ito and Y. Yamamoto, J. Am.
Chem. Soc., 1999, 121, 10850.
21 The electron-rich allyl alcohol 5g was reported to react in a
branched-selective allyl–allyl cross-coupling with 2a (single exam-
ple): see ref. 14.
22 Y. Sumida, S. Hayashi, K. Hirano, H. Yorimitsu and K. Oshima,
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23 Feature article: S. E. Denmark and C. R. Butler, Chem. Commun.,
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This journal is The Royal Society of Chemistry 2011