Organic Letters
Letter
a
Scheme 2. Transformation of the Product
REFERENCES
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a
Reagents and conditions: (a) 2 N HCl/MeOH, rt, 4 h, 92%. (b) 2 N
NaOH aq., EtOH, reflux, 16 h, 96%. (c) DIBAL, THF, −78 °C, 2 h;
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Direct catalytic asymmetric addition of acetonitrile has long
been burdened by insufficient enantioselectivity, which was
addressed herein via strategic use of a unique asymmetric
environment provided by a deep-vaulted biscarbene ligand.
The corresponding α-cyanocarbanion was catalytically gen-
erated by the Ni(II)/biscarbene ligand/tBuOK catalytic
system, and subsequent addition to N-Dpp imines proceeded
with decent stereocontrol. Extrapolation of the present
catalysis to carbonyl-type electrophiles will significantly expand
the utility of alkylnitriles as versatile pronucleophiles, and is
currently ongoing in our laboratory.
ASSOCIATED CONTENT
* Supporting Information
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S
The Supporting Information is available free of charge on the
Experimental procedures, spectroscopic data for new
compounds, and NMR spectra (PDF)
Accession Codes
CCDC 1922993 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
Corresponding Authors
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ORCID
Notes
(9) The use of malononitriles: (a) Arai, T.; Oka, I.; Morihata, T.;
Awata, A.; Masu, H. A Neutral, Chiral, Bis(Imidazolidine)-Derived
NCN-Type Palladium Pincer Complex with Catalytic Activity. Chem.
- Eur. J. 2013, 19, 1554−1557. (b) Chen, X.; Chen, H.; Ji, X.; Jiang,
H.; Yao, Z. J.; Liu, H. Asymmetric One-Pot Sequential Mannich/
Hydroamination Reaction by Organo- and Gold Catalysts: Synthesis
of Spiro[Pyrrolidin-3,2’-Oxindole] Derivatives. Org. Lett. 2013, 15,
1846−1849. (c) Kuwano, S.; Suzuki, T.; Hosaka, Y.; Arai, T. A Chiral
Organic Base Catalyst with Halogen-Bonding-Donor Functionality:
Asymmetric Mannich Reactions of Malononitrile with N-Boc
Aldimines and Ketimines. Chem. Commun. 2018, 54, 3847−3850.
(d) Arai, T.; Nakamura, A. Asymmetric Mannich Reaction of N-Boc
Imines with Alkylmalononitriles Catalyzed by Dinuclear Phosphoi-
minobinol-Pd Complex. Synlett 2019, 30, 1356−1360.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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This work was financially supported by KAKENHI (17H03025
and 18H04276 in Precisely Designed Catalysts with Custom-
ized Scaffolding) from JSPS and MEXT. We are grateful to Dr.
Tomoyuki Kimura, Dr. Ryuichi Sawa, Ms. Yumiko Kubota, and
Dr. Kiyoko Iijima at the Institute of Microbial Chemistry for
technical support in NMR and X-ray crystallographic analysis.
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Org. Lett. XXXX, XXX, XXX−XXX