C O M M U N I C A T I O N S
Table 2. Nickel-LA-Catalyzed Alkenylcyanation of 4-Octyne (2a)
Scheme 1 Plausible Mechanism of the Nickel-LA-Catalyzed
Carbocyanation of Alkynes
anarylgroupwouldberesponsiblefortheobservedregioselectivities.1b
Trans adducts would be derived from phosphine- and/or heat-
mediated isomerization of the initial cis adducts, because the ratios
between the stereoisomers are variable depending on the conditions.
1
b
A silyl group tends to further facilitate the isomerization.
In conclusion, we have demonstrated that Ni-LA catalysts are
significantly effective for carbocyanation of alkynes, and thus not
only aryl cyanides but also alkenyl and alkyl cyanides can be
employed as substrates for the reaction. Application of this
cooperative catalysis to carbocyanation reactions using other nitriles
and/or unsaturated compounds as well as novel catalytic reactions
involving activation of otherwise inert chemical bonds will be
extensively investigated.
a
Isolated yields of isomerically pure products, unless otherwise noted.
b
c
4
Z/4E ) 84:16. The reaction was carried out using Ni(cod)2 (4 mol %),
dppb (4 mol %), and BPh3 (16 mol %). An isomer was also obtained in
2% yield.
d
∼
Acknowledgment. This work has been supported financially
by a Grant-in-Aid for Creative Scientific Research, No. 16GS0209,
and Priority Areas “Advanced Molecular Transformations of Carbon
Resources” from MEXT. Y.N. also acknowledges Mitsubishi
Chemical Corporation Fund, Japan Chemical Innovation Institute,
and Showa Shell Sekiyu Foundation for Promotion of Environ-
mental Research for supports. This paper is dedicated to Professor
Yoshito Kishi of Harvard University on the occasion of his 70th
birthday.
Table 3. Nickel-LA-Catalyzed Alkylcyanation of Alkynes
Supporting Information Available: Detailed experimental pro-
cedures including spectroscopic and analytical data. This material is
available free of charge via the Internet at http://pubs.acs.org.
References
(
(
(
1) (a) Nakao, Y.; Oda, S.; Hiyama, T. J. Am. Chem. Soc. 2004, 126, 13904.
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3) (a) Kamijo, S.; Yamamoto, Y. In Multimetallic Catalysis in Organic
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a
Condition C, PPh2(t-Bu) and AlMe3; condition D, 2-Mes-C6H4-PCy2
b
and AlMe2Cl. Isolated yields of isomerically pure products, unless
otherwise noted. The reaction was carried with a 10 mmol scale. d 99%
c
e
deuteriation. The reaction was carried out using 2.0 equiv of 7a and
Ni(cod)2 (10 mol %). PPhCy2 (20 mol %) and AlMe2Cl (40 mol %) were
used. (Z)/(E) ) 91:9 (93:7 at 3 h).
f
g
yield (entry 3). Under the identical conditions, propionitrile (7c)
gave ethylcyanation product (8ca) in 24% yield (entry 4). The low
yield of 8ca can be ascribed partly to the formation of (E)-2-propyl-
2002, 124, 11598. (e) Tsuchimoto, T.; Kamiyama, S.; Negoro, R.;
Shirakawa, E.; Kawakami, Y. Chem. Commun. 2003, 852. (f) Lou, S.;
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2
-hexenenitrile (9), which was produced possibly via oxidative
5818.
addition of Et-CN bond to Ni(0) followed by â-hydride elimination
and hydrocyanation of 2a.11 Trimethyl(1-octynyl)silane (2e) par-
ticipated in the methylcyanation reaction in a highly regioselective
manner (entry 5).
The observed dramatic effects of LA catalysis would be derived
primarily from acceleration of the oxidative addition of C-CN
bonds by coordination of a cyano group to a LA catalyst as we
expected (Scheme 1),5 but positive effects on the reductive
elimination of C-CN bonds12 and/or other elemental steps could
also be operative. Although a rationale for optimum combinations
of ligands and LA catalysts remains elusive, electron-donating
ligands are generally essential for making the nickel-center electron-
rich enough to cleave C-CN bonds. Coordination of an alkyne in
(4) Garcia, J. J.; Brunkan, N. M.; Jones, W. D. J. Am. Chem. Soc. 2002, 125,
9547.
(
5) (a) Starowieyski, K.; Pasynkiewicz, S.; Boleslawski, M. J. Organomet.
Chem. 1967, 10, 393. (b) Tolman, C. A.; Seidel, W. C.; Druliner, J. D.;
Domaille, P. J. Organometallics 1984, 3, 33. (c) Brunkan, N. M.;
Brestensky, D. M.; Jones, W. D. J. Am. Chem. Soc. 2004, 126, 3627.
6) See Supporting Information for details.
(
(
7) Nakao, Y.; Imanaka, H.; Sahoo, A. K.; Yada, A.; Hiyama, T. J. Am. Chem.
Soc. 2005, 127, 6952.
(
8) Nakao, Y.; Kanyiva, K. S.; Oda, S.; Hiyama, T. J. Am. Chem. Soc. 2006,
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(9) Suginome, M.; Yamamoto, A.; Murakami, M. Angew. Chem., Int. Ed.
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(10) Acrylonitrile gave a complex mixture under the present conditions.
11) Garcia, J. J.; Arevalo, A.; Brunkan, N. M.; Jones, W. D. Organometallics
(
2004, 23, 3997.
(12) Huang, J.; Haar, C. M.; Nolan, S. P.; Marcone, J. E.; Moloy, K. G.
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2
the direction avoiding the steric repulsion between bulkier R and
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J. AM. CHEM. SOC.
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