Organic Letters
Letter
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such an intermediate, as well as understanding the effects of
concentration and base on the enantioselectivity.
In summary, we developed a copper-catalyzed alkynylation of
1-aryl isoquinolinium ions that delivers cyclic α-diaryl tetrasub-
stituted amines in good yields and high enantioselectivities. This
reaction employs a catalyst with commercially available
components, and a wide range of isoquinolines and alkynes can
be used. Notably, the addition of triphenylsilylacetylene is
effective, providing the potential for elaboration of the silyl-
protected alkyne. Our mechanistic studies are consistent with an
aggregated Cu/L1 complex as the active catalyst, consistent with
therecognizedimportanceofdicopperspeciesincopperacetylide
chemistry. Efforts are ongoing to expand the scope and more
deeply understand the mechanism.
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ASSOCIATED CONTENT
* Supporting Information
■
S
TheSupportingInformationisavailablefreeofchargeontheACS
Experimental details and data (PDF)
AUTHOR INFORMATION
■
Corresponding Author
ORCID
Notes
(12) We do not yet understand this dramatic solvent effect. See the
(13) CCDC 1499232 (14) and CCDC 1499233 (30) contain the
supplementary crystallographic data for this paper. These can be
obtained free of charge from The Cambridge Crystallographic Data
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Acknowledgement is gratefully made to the National Science
Foundation (CAREER CHE 1151364). C.A.S. thanks NSF REU
1263018. DatawereacquiredatUDoninstrumentsobtainedwith
assistance of NSF and NIH funding (NSF CHE0421224,
CHE1229234, CHE0840401, and CHE1048367; NIH P20
GM104316, P20 GM103541, and S10 OD016267).
(14) In contrast, no nonlinear effect was observed under the one-pot
(15) Girard, C.; Kagan, H. Angew. Chem., Int. Ed. 1998, 37, 2922.
(16) (a) Díez, J.; Gamasa, M. P.; Panera, M. a. Inorg. Chem. 2006, 45,
10043. (b) Panera, M. a.; Díez, J.; Merino, I.; Rubio, E.; Gamasa, M. P.
Inorg. Chem. 2009, 48, 11147. (c) Nakajima, K.; Shibata, M.;
Nishibayashi, Y. J. Am. Chem. Soc. 2015, 137, 2472.
(17)Forexamplesofmetal/PyBoxcomplexeswithbridginganions,see:
(a) Cuervo, D.; Díez, J.; Gamasa, M. P.;Gimeno, J. Organometallics 2005,
24, 2224. (b) Paredes, P.; Díez, J.; Gamasa, M. P. Organometallics 2008,
27, 2597. (c) Paredes, P.; Díez, J.; Gamasa, M. P. J. Organomet. Chem.
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J. Chem. Crystallogr. 2008, 38, 49.
(18) (a) Ahlquist, M.; Fokin, V. V. Organometallics 2007, 26, 4389.
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(d) Rodionov, V. O.; Fokin, V. V.; Finn, M. G. Angew. Chem., Int. Ed.
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