Journal of the American Chemical Society
COMMUNICATION
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(6) Organocatalytic methods employing proline derivatives have been
developed for the catalytic, asymmetric α-sulfenylation of aldehydes and
enals: (a) Marigo, M.; Wabnitz, T. C.; Fielenbach, D.; Jorgensen, K. A.
Angew. Chem., Int. Ed. 2005, 44, 794–797. (b) Zhao, G.-L.; Rios, R.; Vesely,
J.; Eriksson, L.; Cꢀordova, A. Angew. Chem., Int. Ed. 2008, 47, 8468–8472.
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2010, 132, 7405–7417.
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Figure 1. Proposed catalytic cycle for asymmetric sulfenofunction-
alization.
In conclusion, the first catalytic, asymmetric sulfenylation of
simple alkenes has been achieved using a chiral selenophosphoramide
catalyst. Both inter- and intramolecular thiofunctionalizations
are possible for a variety of olefin types. Efforts are underway
to expand the substrate scope, improve the selectivity of the
reaction, and elucidate the origins of enantioselectivity.
(12) Denmark, S. E.; Vogler, T. Chem.ꢀEur. J. 2009, 15, 11737–
11745.
(13) Denmark, S. E.; Collins, W. R.; Cullen, M. D. J. Am. Chem. Soc.
2009, 131, 3490–3492.
(14) Denmark, S. E.; Beutner, G. L. Angew. Chem., Int. Ed. 2008,
47, 1560–1638.
(15) (a) No background reaction was observed between these two
components at room temperature. (b) No reaction was observed in the
absence of TFA at room temperature.
’ ASSOCIATED CONTENT
S
Supporting Information. Full experimental procedures
b
and characterization data. This material is available free of charge
(16) Piccinini, A.; Kavanagh, S. A.; Connon, P. B.; Connon, S. J. Org.
Lett. 2010, 12, 608–611.
’ AUTHOR INFORMATION
(17) Laurence, C.; Gal, J.-F. Lewis Basicity and Affinity Scales: Data
and Measurement; John Wiley & Sons: Chichester, 2009; Chapter 3.
(18) Bordwell, F. G. Acc. Chem. Res. 1988, 21, 456–463.
(19) Other modifications of the BINAM structure, including sub-
stitution at the 3,30 positions and saturation of the rings, did not increase
enantioselectivity.
(20) N-Thiophenylbenzotriazole and N-thiophenylsaccharin gave
78:22 and 79:21 er, respectively, with 0.2 equiv of catalyst 3c at 23 °C
compared to 79:21 for 1.
Corresponding Author
’ ACKNOWLEDGMENT
Financial support was provided by the National Institutes of
Health (R01 GM08525). D.J.P.K. was partially supported by the
John M. Witt Jr. Fellowship. T.V. thanks the Alexander von
Humboldt Foundation for a Feodor Lynen Research Fellowship.
We thank M. D. Cullen and D. Kalyani for pioneering experi-
mental contributions and M. T. Burk for helpful discussions.
(21) Reactions proceeded to full conversion unless otherwise noted.
Reactions that were not complete within 48 h at ꢀ20 °C were instead
executed at ꢀ10 °C.
(22) For transition-state calculations and cyclization rates of the
analogous seleniranium ions, see: Gruttadauria, M.; Lo Meo, P.; Noto, R.
Tetrahedron 2001, 57, 1819–1826.
(23) However, as discussed below, the ratios may not represent
reactions under kinetic control.
(24) With cis-styrenes, extremely long reaction times (20% conv at 4
d) were observed even at room temperature.
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