Organic Letters
Letter
Scheme 3. Proposed Reaction Mechanism
1
2
radical to the allenic radical affords III, which collapses to
allenols and (AcO)Cu(TEMPO). During the tautomerization
of allenols to 1b, the oxyamine group might have an interaction
with a proton to rationalize the indicated stereochemistry. In
the catalytic cycle, oxygen was not involved, which explained
the product formation in the absence of oxygen (Table 1, entry
ACKNOWLEDGMENTS
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This study was supported by the Korea Research Foundation
No. 2009-0094046 and 2013008819) and a Korea CCS R&D
Center (KCRC) grant from the Korea Government (Ministry
of Education, Science and Technology; No.
(
2
014M1A8A1049294).
2
). However, oxygen might promote the reoxidation of
TEMPOH to the TEMPO radical, to increase the concen-
tration of TEMPO starting materials.
11c
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(
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2
(
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1
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ASSOCIATED CONTENT
Supporting Information
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AUTHOR INFORMATION
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Notes
(5) Pradhan, P. P.; Bobbitt, J. M.; Bailey, W. F. Org. Lett. 2006, 8,
The authors declare no competing financial interest.
5485−5487.
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dx.doi.org/10.1021/ol502341f | Org. Lett. XXXX, XXX, XXX−XXX