Organic Letters
Letter
We have developed a facile approach that allows for Ni(cod)2
to be used on the benchtop. Our strategy involves the
(3) SciFinder searching for bis(1,5-cyclooctadiene)nickel(0) being
used as a reagent yielded hits corresponding to 848 original manuscripts
since 1985 (accessed 28 April, 2016).
preparation of paraffin−Ni(cod) capsules, which are stable to
2
(4) In a recent seminal study, Buchwald demonstrated that Pd/ligand
air and moisture. The capsules, which will soon be commercially
1
4
combinations could be dosed into paraffin capsules; see: Sather, A. C.;
Lee, H. G.; Colombe, J. R.; Zhang, A.; Buchwald, S. L. Nature 2015, 524,
available, promote a range of Ni(cod) -catalyzed trans-
2
formations, including reactions of amides, aminations, alkyl
Suzuki−Miyaura couplings, oxidative annulations, esterifications,
and amidations. We hope that the method disclosed herein will
help nurture the burgeoning field of nickel catalysis in academia
and industry.
2
(
08−211.
5) Paraffin has been used to impart stability to air and moisture
sensitive reagents in a variety of contexts. For examples of paraffin-
reagent dispersions, see: (a) Taber, D. F.; Li, H.-Y. U.S. Patent
20050288257, Dec. 29, 2005. (b) Fang, Y.; Liu, Y.; Ke, Y.; Guo, C.; Zhu,
N.; Mi, X.; Ma, Z.; Hu, Y. Appl. Catal., A 2002, 235, 33−38. (c) Taber, D.
F.; Frankowski, K. J. J. Org. Chem. 2003, 68, 6047−6048. (d) Taber, D.
F.; Nelson, C. G. J. Org. Chem. 2006, 71, 8973−8974. For examples of
reagents encapsulated in paraffin, see: (e) Kosak, K. M.; Kosak, M. K.
U.S. Patent 5413924, May 9, 1995. (f) Shen, C.; Spannenberg, A.; Wu,
X.-F. Angew. Chem., Int. Ed. 2016, 55, 5067−5070.
ASSOCIATED CONTENT
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Supporting Information
(
6) Typically, the capsules used in Figures 3 and 4 contained 2−14 mg
of Ni(cod) , although it is estimated that these capsules could hold up to
2
(
2
2
At the conclusion of a reaction, the paraffin wax can be removed by dry-
AUTHOR INFORMATION
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7) (a) Hie, L.; Fine Nathel, N. F.; Shah, T. K.; Baker, E. L.; Hong, X.;
and eluting with hexanes and
2
2
(
Yang, Y.-F.; Liu, P.; Houk, K. N.; Garg, N. K. Nature 2015, 524, 79−83.
(b) Weires, N. A.; Baker, E. L.; Garg, N. K. Nat. Chem. 2016, 8, 75−79.
(c) Simmons, B. J.; Weires, N. A.; Dander, J. E.; Garg, N. K. ACS Catal.
Author Contributions
†These authors contributed equally to this work. The manuscript
was written through contributions of all authors. All authors have
given approval to the final version of the manuscript.
2
016, 6, 3176−3179. (d) Baker, E. L.; Yamano, M. M.; Zhou, Y.;
Anthony, S. M.; Garg, N. K. Nat. Commun. 2016, 7, 11554.
8) Ramgren, S. D.; Silberstein, A. L.; Yang, Y.; Garg, N. K. Angew.
(
Notes
Chem., Int. Ed. 2011, 50, 2171−2173.
(
9) Zhou, J.; Fu, G. C. J. Am. Chem. Soc. 2004, 126, 1340−1341.
The authors declare no competing financial interest.
(10) Shiota, H.; Ano, Y.; Aihara, Y.; Fukumoto, Y.; Chatani, N. J. Am.
Chem. Soc. 2011, 133, 14952−14955.
(11) Whittaker, A. M.; Dong, V. M. Angew. Chem., Int. Ed. 2015, 54,
ACKNOWLEDGMENTS
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312−1315.
The authors are grateful to Boehringer Ingelheim, Bristol-Myers
Squibb, the Camille and Henry Dreyfus Foundation, the
University of California, Los Angeles, the NSF (N.A.W., DGE-
12) The robustness of the paraffin−Ni(cod) capsules with regard to
2
exposure to water was also tested. A capsule that had been submerged in
water for 1 h and subsequently dried with a paper towel was found to
promote the esterification of amide 2 with (−)-menthol (3) to give 4 in
1
144087), the Foote Family (N.A.W. and J.E.D.), and the UCLA
Gold Shield Alumnae for financial support. These studies were
9
4% yield.
supported by shared instrumentation grants from the NSF
(
13) The esterification of amide 2 with (−)-menthol (3) was also
(CHE-1048804) and the NIH NCRR (S10RR025631).
carried out using nonencapsulated Ni(cod) and SIPr that had been
2
exposed to air. After only 1 h of air exposure, the attempted esterification
REFERENCES
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(
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Resmerita, A.-M.; Garg, N. K.; Percec, V. Chem. Rev. 2011, 111, 1346−
(
14) Paraffin capsules containing Ni(cod) and Ni(cod) /SIPr will
2 2
soon be available commercially from TCI (TCIchemicals.com) and
Sigma-Aldrich. The capsules and their TCI product numbers are as
follows (Sigma-Aldrich product numbers are pending): Bis(1,5-
cyclooctadiene)nickel(0) (Wax encapsulated): B5417. Bis(1,5-cyclo-
octadiene)nickel(0)−1,3-Bis(2,6-diisopropylphenyl)imidazolidin-2-yli-
dene (Wax encapsulated): B5418.
1
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2
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(
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