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L. Roiser et al.
Letter
Synlett
pounds as ammonium ylide precursors for epoxide forma-
tions is not as effective as the comparable use for sulfonium
ylide mediated reactions.
(4) For ammonium ylide mediated cyclopropanations, see:
(a) Gaunt, M. J.; Johansson, C. C. C. Chem. Rev. 2007, 107, 5596.
(b) Johansson, C. C. C.; Bremeyer, N.; Ley, S. V.; Owen, D. R.;
Smith, S. C.; Gaunt, M. J. Angew. Chem. Int. Ed. 2006, 45, 6024.
(c) Papageorgiou, C. D.; Cubillo de Dios, M. A.; Ley, S. V.; Gaunt,
M. J. Angew. Chem. Int. Ed. 2004, 43, 4641. (d) Bremeyer, N.;
Smith, S. C.; Ley, S. V.; Gaunt, M. J. Angew. Chem. Int. Ed. 2004,
43, 2681. (e) Papageorgiou, C. D.; Ley, S. V.; Gaunt, M. J. Angew.
Chem. Int. Ed. 2003, 42, 828.
(5) For benzylic ammonium ylide mediated epoxidations, see:
(a) Kimachi, T.; Kinoshita, H.; Kusaka, K.; Takeuchi, Y.; Aoe, M.;
Ju-ichi, M. Synlett 2005, 842. (b) Kinoshita, H.; Ihoriya, A.; Ju-
ichi, M.; Kimachi, T. Synlett 2010, 2330. (c) Robiette, R.; Conza,
M.; Aggarwal, V. K. Org. Biomol. Chem. 2006, 4, 621. (d) Xiao, X.;
Lin, D.; Tong, S.; Mo, H. Synlett 2011, 2823.
In conclusion, a high-yielding protocol for the synthesis
of stilbene oxides using ammonium ylides has been devel-
oped.19,20 The nature of the amine leaving group plays a cru-
cial role herein and it was found that trimethylamine gives
significantly higher yields than DABCO or quinuclidine. The
nature of the amine group also influences the diastereose-
lectivity in these reactions. A detailed DFT study allows un-
derstanding the different yields and selectivities when us-
ing different amine leaving groups and aryl substituents.
(6) For cyano-stabilized ammonium ylide mediated epoxidations,
see: (a) Jonczyk, A.; Konarska, A. Synlett 1999, 1085.
(b) Kowalkowska, A.; Sucholbiak, D.; Jonczyk, A. Eur. J. Org.
Chem. 2005, 925. (c) Alex, A.; Larmanjat, B.; Marrot, J.; Couty, F.;
David, O. Chem. Commun. 2007, 2500.
(7) For amide-stabilized ammonium ylide mediated epoxidations,
see: (a) Waser, M.; Herchl, R.; Müller, N. Chem. Commun. 2011,
47, 2170. (b) Herchl, R.; Stiftinger, M.; Waser, M. Org. Biomol.
Chem. 2011, 9, 7023. (c) Pichler, M.; Novacek, J.; Robiette, R.;
Poscher, V.; Himmelsbach, M.; Monkowius, U.; Müller, N.;
Waser, M. Org. Biomol. Chem. 2015, 13, 2092. (d) Novacek, J.;
Roiser, L.; Zielke, K.; Robiette, R.; Waser, M. Chem. Eur. J. 2016,
DOI: 10.1002/chem.201602052.
Acknowledgment
This work was supported by the Austrian Science Funds (FWF): Proj-
ect No. P26387-N28. Computational resources have been provided by
the supercomputing facilities of the Université catholique de Louvain
(CISM/UCL) and the Consortium des Équipements de Calcul Intensif
en Fédération Wallonie Bruxelles (CÉCI) funded by the Fond de la Re-
cherche Scientifique de Belgique (F.R.S.-FNRS) under convention
2.5020.11. The NMR spectrometers used were acquired in collabora-
tion with the University of South Bohemia (CZ) with financial support
from the European Union through the EFRE INTERREG IV ETC-AT-CZ
program (project M00146, ‘RERI-uasb’). RR is a Chercheur qualifié of
the F.R.S.-FNRS.
(8) For ammonium ylide mediated aziridinations, see: (a) Yadav, L.
D. S.; Kapoor, R.; Garima, Synlett 2009, 3123. (b) Aichhorn, S.;
Gururaja, G. N.; Reisinger, M.; Waser, M. RSC Adv. 2013, 3, 4552.
(9) Aggarwal, V. K.; Harvey, J. N.; Robiette, R. Angew. Chem. Int. Ed.
2005, 44, 5468.
Supporting Information
Supporting information for this article is available online at
(10) For a recent report on selenium ylide mediated epoxidations,
see: Banach, A.; Scianowski, J.; Uzarewicz-Baig, M.; Wojtczak, A.
Eur. J. Org. Chem. 2015, 3477.
S
u
p
p
ortioInfgrmoaitn
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p
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(11) Ylide addition onto the aldehyde occurs without enthalpic
barrier and thus no significant selectivity is expected for this
step.
(12) Winberg, H. E.; Fawcett, F. S.; Mochel, W. E.; Theobald, C. W.
J. Am. Chem. Soc. 1960, 82, 1428.
(13) Computations have been carried out at the B3LYP-D3/6-
311+G(d,p)//B3LYP/6-31G* level of theory, including a contin-
uum description of dichloromethane solvent for both the geom-
etry optimization and the single-point energy calculation using
Jaguar, version 8.5; Schrodinger, Inc.: New York, 2014. Thermal
and entropic contributions to free energy were computed by
performing frequency calculations at the B3LYP/6-31G (d) level
of theory using the fine DFT grid within Jaguar. See ESI for full
computational details and data.
(14) In the earlier computational study (ref. 5c) only electronic ener-
gies were obtained, but no entropic and thermal contributions
were included.
(15) Betaine formation occurs without enthalpic barrier. A set of
constrained geometry optimization at successively smaller
values of the C–C distance showed that the interaction between
reactants is uniformly attractive. The free-energy barrier of a
diffusion controlled reaction can, however, be estimated at 3.7
kcal/mol in THF at 40 °C (see Supporting Information for
details).
References and Notes
(1) For selected reviews, see: (a) Aggarwal, V. K. In Comprehensive
Asymmetric Catalysis; Jacobsen, E. N.; Pfaltz, A.; Yamamoto, H.,
Eds.; Springer: New York, 1999, Vol. 2 679. (b) McGarrigle, E.
M.; Myers, E. L.; Illa, O.; Shaw, M. A.; Riches, S. L.; Aggarwal, V. K.
Chem. Rev. 2007, 107, 5841.
(2) For seminal work on sulfur ylides, see: (a) Corey, E. J.;
Chaykovsky, M. J. Am. Chem. Soc. 1962, 84, 867. (b) Corey, E. J.;
Chaykovsky, M. J. Am. Chem. Soc. 1965, 87, 1353. (c) Johnson, A.
W.; Lacount, R. B. Chem. Ind. 1958, 1440.
(3) For examples highlighting the use of sulfur ylides in epoxidation
reactions, see: (a) Zhou, Y.-G.; Hou, X.-L.; Dai, L.-X.; Xia, L.-J.;
Tang, M.-H. J. Chem. Soc., Perkin Trans. 1 1999, 77. (b) Zanardi, J.;
Leriverend, C.; Aubert, D.; Julienne, K.; Metzner, P. J. Org. Chem.
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J.-L. J. Am. Chem. Soc. 2002, 124, 9964. (d) Aggarwal, V. K.;
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Briere, J.-F.; Jaffres, P.-A.; Metzner, P. J. Org. Chem. 2005, 70,
4166. (f) Aggarwal, V. K.; Charmant, J. P. H.; Fuentes, D.; Harvey,
J. N.; Hynd, G.; Ohara, D.; Picoul, W.; Robiette, R.; Smith, C.;
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Lusi, M.; McGarrigle, E. M.; Aggarwal, V. K. J. Am. Chem. Soc.
2013, 135, 11951.
(16) Robiette, R.; Trieu-Van, T.; Aggarwal, V. K.; Harvey, J. N. J. Am.
Chem. Soc. 2016, 138, 734.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2016, 27, A–F