R. Soler-Yanes, M. Guisán-Ceinos, E. Buñuel, D. J. Cárdenas
SHORT COMMUNICATION
evaporated under vacuum, and the product was purified by column
chromatography.
Supporting Information (see footnote on the first page of this arti-
cle): Full experimental details characterization data, and copies of
1
13
the H NMR and C NMR spectra of all key intermediates and
final products.
Acknowledgments
This work was supported by the Ministerio de Ciencia e Innovación
(
MICINN) (grant number CTQ2010-15927, and a fellowship to
R. S.-Y.) and the Comunidad Autónoma de Madrid (CAM) (pro-
ject AVANCAT). The authors thank the Universidad Autónoma
de Madrid (UAM) for a fellowship to M. G.-C.
[
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Scheme 5. Plausible reaction pathway.
1
4 (Scheme 4) indicates that they are formed in competitive [2] For reviews on alkyl–alkyl metal-catalyzed cross-coupling reac-
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pathways that do not have very different reaction rates. This
may be a consequence of the fact that the reactivity of
benzyl halides is higher than that of simple alkyl derivatives,
for which addition of TEMPO may inhibit the C–C cross-
coupling, as shown in our previous studies.[ The absence
of coupling of TEMPO with the electrophile points to the
3
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1
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In conclusion, we found conditions for the fast Ni-cata-
lyzed cross-coupling reactions of benzyl chlorides with alk-
ylmagnesium reagents. In the presence of TMEDA, the re-
action tolerates several functional groups. Diallyl ether was
proven to confer special properties on the Ni complexes
that boosted the reaction rate and led to quantitative trans-
formations by using a low catalyst loading at –30 °C for
substrates containing donating groups. This system did,
however, fail for electron-deficient substrates. These trans-
formations avoid the use of bromides and iodides and show
great potential applicability.
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Representative Procedure for the Cross-Coupling Reaction in the
Presence of Diallyl Ether: A vial was charged with Ni(acac)
2
(
(
5.2 mg, 0.02 mmol), the corresponding benzyl chloride
0.41 mmol), and a stir bar in air. The vial was sealed with a septum
and dried under vacuum and backfilled with Ar. Then, dry THF
2 mL) and diallyl ether (50 μL, 0.406 mmol) were added. The re-
(
sulting mixture was stirred at 23 °C for 5 min and then cooled in
an ice bath. A solution of alkylmagnesium halide in THF
9476.
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(0.81 mmol) was added dropwise at 0 °C. During the addition the
solution turned orange. After the addition of the Grignard reagent,
the mixture was stirred for 10 min. The resulting yellow solution
was quenched with a saturated aqueous NH
ous layer was extracted several times with ethyl acetate, and the
combined organic layer was dried with MgSO . The solvent was
4
Cl solution. The aque-
4
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