Organic Letters
Letter
To illustrate the utility of the reaction products, iodocycliza-
tion and cycloaddition transformations have been performed
(Scheme 6). In the presence of I2 and NaHCO3, the products 3a
ACKNOWLEDGMENTS
We thank the Welch Foundation (grant E-1744) for generous
financial support.
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Scheme 6. Product Transformations
REFERENCES
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and 23a smoothly underwent iodocyclization to form iodo-
substituted pyrrolidine 38a and piperidine 38b in 89% and 81%
yields, respectively.15 When using alkynyl amine 4a for
iodocyclization, AgOAc was needed to improve the reaction
rate and yield;16 the iodopyrroline 39 was thus obtained in 83%
yield. Importantly, azepine derivatives can be constructed
efficiently and selectively. After a γ-amino ketone intermediate
was formed by a hydration reaction of the amine 4a, it underwent
a AgSbF6-catalyzed [5 + 2]-cycloaddition with phenylacetylene
to afford synthetically useful azepine 40 in 75% yield.17
In conclusion, we report a general procedure to synthesize β,β-
and γ,γ-substituted amines by nucleophilic ring opening of
aziridines and azetidines under transition-metal-free and open-air
conditions. A range of substituted amines could be straightfor-
wardly accessed from readily available alkynyl, alkenyl, aryl, and
heteroaryl trifluoroborates. A mechanistic proposal has been
made on the basis of control experiments. The reaction products
can be easily transformed to useful amine scaffolds.
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ASSOCIATED CONTENT
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(7) (a) Welch, C. J.; Albaneze-Walker, J.; Leonard, W. R.; Biba, M.;
DaSilva, J.; Henderson, D.; Laing, B.; Mathre, D. J.; Spencer, S.; Bu, X.;
Wang, T. Org. Process Res. Dev. 2005, 9, 198. (b) Garrett, C. E.; Prasad, K.
Adv. Synth. Catal. 2004, 346, 889.
S
* Supporting Information
The Supporting Information is available free of charge on the
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Complete experimental procedures and compound
characterization data (PDF)
Accession Codes
graphic data for this paper. These data can be obtained free of
Crystallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: +44 1223 336033.
(13) Attempts to synthesize LiHSO4 were made. However, it is
extremely hygroscopic and difficult to purify.
(14) A control experiment with excess fluoride present (KHF2)
showed no impact on reactivity, indicating that the boron of the
nucleophile remains coordinatively saturated. Consequently, Lewis
acid/Lewis base coordination for facial direction is unlikely.
(15) Davis, F. A.; Song, M.; Augustine, A. J. Org. Chem. 2006, 71, 2779.
(16) Ding, C. H.; Dai, L. X.; Hou, X. L. Tetrahedron 2005, 61, 9586.
(17) Zhou, M. B.; Song, R. J.; Wang, C. Y.; Li, J. H. Angew. Chem., Int.
Ed. 2013, 52, 10805.
AUTHOR INFORMATION
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Corresponding Author
ORCID
Notes
The authors declare no competing financial interest.
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Org. Lett. XXXX, XXX, XXX−XXX