Edge Article
Chemical Science
D. Hoppe and T. Hense, Angew. Chem., Int. Ed. Engl., 1997,
6 (a) F. P. Touchard, N. Capelle and M. Mercier, Adv. Synth.
Catal., 2005, 347, 707; (b) A. Gans ¨a uer, C.-A. Fan, F. Keller
and J. Keil, J. Am. Chem. Soc., 2007, 129, 3484; (c)
S. Pachali, C. Hofmann, G. Rapp, R. Schobert, A. Baro,
W. Frey and S. Laschat, Eur. J. Org. Chem., 2009, 2828.
7 (a) S. S. Sohn, E. L. Rosen and J. W. Bode, J. Am. Chem. Soc.,
2004, 126, 14370; (b) H. U. Vora and T. Rovis, J. Am. Chem.
Soc., 2010, 132, 2860.
8 For enal activations under iminium catalysis, similar
problems exist, especially for intermolecular reactions. For
examples, see: (a) K. A. Ahrendt, C. J. Borths and
D. W. C. MacMillan, J. Am. Chem. Soc., 2000, 122, 4243; (b)
A. I. Gerasyuto and R. P. Hsung, J. Org. Chem., 2007, 72,
2476; (c) H. M. Sklenicka, R. P. Hsung, M. J. McLaughlin,
L. Wei, A. I. Gerasyuto and W. B. Brennessel, J. Am. Chem.
Soc., 2002, 124, 10435.
9 For selected examples of reactions involving enal substrates,
see: (a) W. Notz, F. Tanaka and C. F. Barbas III, Acc. Chem.
Res., 2004, 37, 580; (b) A. Erkkil ¨a , I. Majander and
P. M. Pihko, Chem. Rev., 2007, 107, 5416; (c) S. Mukherjee,
J. W. Yang, S. Hoffmann and B. List, Chem. Rev., 2007, 107,
5471; (d) P. Melchiorre, M. Marigo, A. Carlone and
G. Bartoli, Angew. Chem., Int. Ed., 2008, 47, 6138; (e)
S. Bertelsen and K. A. Jørgensen, Chem. Soc. Rev., 2009, 38,
2178. Also see ref. 3
36, 2282.
2
For selected reviews see: (a) D. Enders, O. Niemeier and
A. Henseler, Chem. Rev., 2007, 107, 5606; (b) N. Marion,
S. S. D ´ı ez-Gonz ´a lez and S. P. Nolan, Angew. Chem., Int. Ed.,
2007, 46, 2988; (c) V. Nair, S. Vellalath and B. P. Babu,
Chem. Soc. Rev., 2008, 37, 2691; (d) E. M. Phillips, A. Chan
and K. A. Scheidt, Aldrichimica Acta, 2009, 42, 55; (e)
J. R. de-Alaniz and T. Rovis, Synlett, 2009, 1189; (f)
J. L. Moore and T. Rovis, Top. Curr. Chem., 2010, 291, 77;
(
g) A. T. Biju, N. Kuhl and F. Glorius, Acc. Chem. Res., 2011,
44, 1182; (h) K. Hirano, I. Piel and F. Glorius, Chem. Lett.,
2011, 40, 786; (i) P.-C. Chiang and J. W. Bode, TCI MAIL,
2011, 149, 2; (j) H. U. Vora and T. Rovis, Aldrichimica Acta,
2011, 44, 3; (k) H. U. Vora, P. Wheeler and T. Rovis, Adv.
Synth. Catal., 2012, 354, 1617; (l) J. Douglas, G. Churchill
and A. D. Smith, Synthesis, 2012, 44, 2295; (m) S. D. Sarkar,
A. Biswas, R. C. Samanta and A. Studer, Chem.–Eur. J.,
2013, 19, 4664.
3
For reviews on homoenolate equivalents, see: (a) V. Nair,
S. Vellalath and B. P. Babu, Chem. Soc. Rev., 2008, 37, 2691;
(
b) V. Nair, R. S. Menon, A. T. Biju, C. R. Sinu, R. R. Paul,
A. Jose and V. Sreekumar, Chem. Soc. Rev., 2011, 40, 5336.
For selected examples involving homoenolates, see: (c)
S. S. Sohn, E. L. Rosen and J. W. Bode, J. Am. Chem. Soc.,
2004, 126, 14370; (d) C. Burstein and F. Glorius, Angew. 10 (a) Y. Matsumoto and K. Tomioka, Tetrahedron Lett., 2006,
Chem., Int. Ed., 2004, 43, 6205; (e) M. He and J. W. Bode,
Org. Lett., 2005, 7, 3131; (f) C. Burstein, S. Tschan, X. L. Xie
and F. Glorius, Synthesis, 2006, 2418; (g) V. Nair,
S. Vellalath, M. Poonoth, R. Mohan and E. Suresh, Org.
47, 5843; (b) J. Kaeobamrung, J. Mahatthananchai,
P. Zheng and J. W. Bode, J. Am. Chem. Soc., 2010, 132,
8810; (c) S. Wei, X. Wei, X. Su, J. You and Y. Ren, Chem.–
Eur. J., 2011, 17, 5965.
Lett., 2006, 8, 507; (h) V. Nair, S. Vellalath, S. Poonoth and 11 (a) C. Simal, T. Lebl, A. M. Z. Slawin and A. D. Smith, Angew.
E. Suresh, J. Am. Chem. Soc., 2006, 128, 8736; (i) A. Chan
and K. A. Scheidt, J. Am. Chem. Soc., 2007, 129, 5334; (j)
P.-C. Chiang, J. Kaeobamrung and J. W. Bode, J. Am. Chem.
Soc., 2007, 129, 3520; (k) M. Wadamoto, E. M. Phillips,
Chem., Int. Ed., 2012, 51, 3653; (b) K. Jiang, B. Tiwari and
Y. R. Chi, Org. Lett., 2012, 14, 2382; (c) L. Hao, Y. Du,
H. Lv, X. Chen, H. Jiang, Y. Shao and Y. R. Chi, Org. Lett.,
2012, 14, 2154. Also see ref. 4c.
T. E. Reynolds and K. A. Scheidt, J. Am. Chem. Soc., 2007, 12 An acyl anion-oxy-Cope rearrangement pathway was
1
29, 10098; (l) V. Nair, B. P. Babu, S. Vellalath and
proposed for the formation of lactam product 4a: M. He
and J. W. Bode, J. Am. Chem. Soc., 2008, 130, 418.
E. Suresh, Chem. Commun., 2008, 747; (m) E. M. Phillips,
T. E. Reynolds and K. A. Scheidt, J. Am. Chem. Soc., 2008, 13 CCDC 884437 contains the supplementary crystallographic
30, 2416; (n) Y. Li, Z.-A. Zhao, H. He and S.-L. You, Adv. data for 3g.
Synth. Catal., 2008, 350, 1885; (o) J. Seayad, P. K. Patra, 14 (a) J. E. Thomson, K. Rix and A. D. Smith, Org. Lett., 2006, 8,
1
Y. Zhang and J. Y. Ying, Org. Lett., 2008, 10, 953; (p)
L. Yang, B. Tan, F. Wang and G. Zhong, J. Org. Chem.,
3785; (b) J. E. Thomson, C. D. Campbell, C. Concell ´o n,
N. Duguet, K. Rix, A. M. Z. Slawin and A. D. Smith, J. Org.
Chem., 2008, 73, 2784; (c) C. D. Campbell, C. J. Collett,
J. E. Thomson, A. M. Z. Slawin and A. D. Smith, Org.
Biomol. Chem., 2011, 9, 4205.
2009, 74, 1744.
4
The Scheidt and Rovis groups developed creative strategies
in accessing different diastereoselectivities via NHC/Lewis
acid or Bronsted acid cooperative catalysis respectively. For 15 J. Kaeobamrung and J. W. Bode, Org. Lett., 2009, 11, 677.
examples, see: (a) B. Cardinal-David, D. E. Raup and
K. A. Scheidt, J. Am. Chem. Soc., 2010, 132, 5345; (b)
D. T. Cohen and K. A. Scheidt, Chem. Sci., 2012, 3, 53; (c)
X. Zhao, D. A. DiRocco and T. Rovis, J. Am. Chem. Soc.,
Following one referee’s suggestion, we tried Bode’s a-
hydroxy enone substrate to react with cis-enal under our
conditions. No product between enal and enone was
observed. Instead, enone was recovered; most enal was
recovered as a mixture of cis/trans-isomers; the enal was
partly converted to acids.
2011, 133, 12466.
5
Very recently, Smith et al. reported cis-a,b-unsaturated
anhydrides as substrates in isothiourea-catalyzed reactions
to obtain opposite diastereoselectivity: E. R. T. Robinson,
C. Fallan, C. Simal, A. M. Z. Slawin and A. D. Smith, Chem.
Sci., 2013, 4, 2193.
This journal is ª The Royal Society of Chemistry 2013
Chem. Sci.