LETTER
Reactions of Nitroalkenes with Nitroalkanes or Sulfur Ylides
(6) Lu, J.; Toy, P. H. Chem. Rev. 2009, 109, 815.
2989
heterogeneous 18 has the advantages over homogeneous
9 of being readily recovered and reused.
(7) For a review regarding polymer-supported phosphines, see:
Guino, M.; Hii, K. K. M. Chem. Soc. Rev. 2007, 36, 608.
(8) For our work regarding cross-linked polymer-supported
phosphines, see: (a) Choi, M. K. W.; He, H. S.; Toy, P. H.
J. Org. Chem. 2003, 68, 9831. (b) Zhao, L. J.; He, H. S.;
Shi, M.; Toy, P. H. J. Comb. Chem. 2004, 6, 680. (c) Zhao,
L.-J.; Kwong, C. K.-W.; Shi, M.; Toy, P. H. Tetrahedron
2005, 61, 12026. (d) Leung, P. S.-W.; Teng, Y.; Toy, P. H.
Synlett 2010, 1997. (e) Teng, Y.; Toy, P. H. Synlett 2011,
551.
(9) For our work regarding non-cross-linked polymer-supported
phosphines, see: (a) Harned, A. M.; He, H. S.; Toy, P. H.;
Flynn, D. L.; Hanson, P. R. J. Am. Chem. Soc. 2005, 127,
52. (b) He, H. S.; Yan, J. J.; Shen, R.; Zhuo, S.; Toy, P. H.
Synlett 2006, 563.
In conclusion, we have extended the concept of bifunc-
tional polymeric organocatalysts to the synthesis of ho-
mogeneous (non-cross-linked) and heterogeneous (cross-
linked) polymers functionalized with both amine and thio-
urea catalytic groups. These polymers were used effec-
tively as catalysts for reactions involving the addition of
nitroalkanes to nitroalkenes and cycloaddition reactions
between nitroalkenes and sulfur ylides. For both of these
reaction types, good substrate variability and high stereo-
selectivity were observed. While soluble polymer 9 was
generally more efficient and could be used at lower load-
ing than insoluble polymer 18, the latter was removable
by filtration and readily reused. We are currently examin-
ing other applications of 9 and 18 in the context of com-
plex organic molecule synthesis and will report our
findings shortly.
(10) Kwong, C. K.-W.; Huang, R.; Zhang, M.; Shi, M.; Toy,
P. H. Chem. Eur. J. 2007, 13, 2369.
(11) For a review of alkyne to diene isomerization reactions, see:
Kwong, C. K.-W.; Fu, M. Y.; Lam, C. S.-L.; Toy, P. H.
Synthesis 2008, 2307.
(12) (a) Kwong, C. K.-W.; Fu, M. Y.; Law, H. C.-H.; Toy, P. H.
Synlett 2010, 2617. (b) Fu, M. Y.; Guo, J.; Toy, P. H. Synlett
2011, 989.
(13) (a) But, T. Y. S.; Tashino, Y.; Togo, H.; Toy, P. H. Org.
Biomol. Chem. 2005, 3, 970. (b) Chung, C. W. Y.; Toy,
P. H. J. Comb. Chem. 2007, 9, 155. (c) Lu, J.; Toy, P. H.
Synlett 2011, 659.
Supporting Information for this article is available online at
Acknowledgment
(14) Lu, J.; Toy, P. H. Synlett 2011, 1723.
(15) Leung, P. S.-W.; Teng, Y.; Toy, P. H. Org. Lett. 2010, 12,
This research was supported financially by the University of Hong
Kong and the Research Grants Council of the Hong Kong S. A. R.,
P. R. of China (Project No. HKU 704108P).
4996.
(16) Rabalakos, C.; Wulff, W. D. J. Am. Chem. Soc. 2008, 130,
13524.
(17) (a) Lu, L.-Q.; Cao, Y.-J.; Liu, X.-P.; An, J.; Yao, C.-J.;
Ming, Z.-H.; Xiao, W.-J. J. Am. Chem. Soc. 2008, 130,
6946. (b) Lu, L.-Q.; Li, F.; An, J.; Zhang, J.-J.; An, X.-L.;
Hua, Q.-L.; Xiao, W.-J. Angew. Chem. Int. Ed. 2009, 48,
9542.
(18) For a related bifunctional mesoporous silica material, see:
Puglisi, A.; Annunziata, R.; Benaglia, M.; Cozzi, F.;
Gervasini, A.; Bertacche, V.; Sala, M. C. Adv. Synth. Catal.
2009, 351, 219.
References and Notes
(1) For selected reviews regarding polymer-supported
organocatalysts, see: (a) Benaglia, M.; Puglisi, A.; Cozzi, F.
Chem. Rev. 2003, 103, 3401. (b) Benaglia, M. New J. Chem.
2006, 30, 1525. (c) Cozzi, F. Adv. Synth. Catal. 2006, 348,
1367. (d) Gruttadauria, M.; Giacalone, F.; Noto, R. Chem.
Soc. Rev. 2008, 37, 1666. (e) Kristensen, T. E.; Hansen, T.
Eur. J. Org. Chem. 2010, 3179.
(2) For selected reviews regarding bifunctional organocatalysts,
see: (a) Marcelli, T.; van Maarseveen, J. H.; Hiemstra, H.
Angew. Chem. Int. Ed. 2006, 45, 7496. (b) Kano, T.;
Maruoka, K. Chem. Commun. 2008, 5465. (c) Paull, D. H.;
Abraham, C. J.; Scerba, M. T.; Alden-Danforth, E.; Lectka,
T. Acc. Chem. Res. 2008, 41, 655. (d) Lattanzi, A. Chem.
Commun. 2009, 1452. (e) Liu, X.; Lin, L.; Feng, X. Chem.
Commun. 2009, 6145. (f) Grotjahn, D. B. Top. Catal. 2010,
53, 1009. (g) Ting, A.; Goss, J. M.; McDougal, N. T.;
Schaus, S. E. Top. Curr. Chem. 2010, 291, 145.
(19) Toy, P. H.; Reger, T. S.; Janda, K. D. Org. Lett. 2000, 2,
2205.
(20) See Supporting Information for details.
(21) Mampreian, D. M.; Hoveyda, A. H. Org. Lett. 2004, 6, 2829.
(22) General Procedure for the Michael Addition Reactions
of Nitroalkanes to Nitrostyrenes Catalyzed by Polymer 9
Nitrostyrene 13a–i (1 mmol) and catalyst 9 (0.05 mmol)
were dissolved in 12 (2.6 mL, 30 mmol). The mixture was
stirred at r.t. for 20 h, and then the reaction mixture was
purified directly by column chromatography to afford the
desired product14a–i as a mixture of stereoisomers. The syn/
anti ratio was determined by 1H NMR analysis of the crude
product mixture.
(3) For a landmark example of a trifunctional organocatalyst,
see: Ema, T.; Tanida, D.; Matsukawa, T.; Sakai, T. Chem.
Commun. 2008, 957.
(23) General Procedure for the Cycloaddition Reactions
Catalyzed by Polymer 9
(4) (a) Overberger, C. G.; Salamone, J. C.; Yaroslavsky, S.
J. Am. Chem. Soc. 1967, 89, 6231. (b) Overberger, C. G.;
Maki, H. Macromolecules 1970, 3, 220. (c) Overberger, C.
G.; Maki, H. Macromolecules 1970, 3, 214. (d)Overberger,
C. G.; Pacansky, T. J.; Lee, J.; St. Pierre, T.; Yaroslavsky, S.
J. Polym. Sci., Polym. Symp. 1974, 46, 209. (e) Overberger,
C. G.; Podsiadly, C. J. Bioorg. Chem. 1974, 3, 35.
(f) Overberger, C. G.; Podsiadly, C. J. Bioorg. Chem. 1974,
3, 16.
Nitrostyrene 13a,c,d,f–l (0.5 mmol) and 9 (0.05 mmol) were
dissolved in CHCl3 (1 mL). Sulfur ylide 15a–c (0.6 mmol)
in CHCl3 (1 mL) was then added dropwise to the mixture.
After stirring at r.t. for 24 h, the reaction mixture was
purified directly by column chromatography to afford the
desired products 16a–l. The anti/syn ratio was determined by
1H NMR analysis of the crude product mixture.
(24) For the Jandajel concept, see: (a) Toy, P. H.; Janda, K. D.
Tetrahedron Lett. 1999, 40, 6329. (b) Toy, P. H.; Reger, T.
S.; Janda, K. D. Aldrichimica Acta 2000, 33, 87. (c) Toy, P.
(5) For conceptually similar research using imprinted polymers,
see: Sellergren, B.; Karmalkar, R. N.; Shea, K. J. J. Org.
Chem. 2000, 65, 4009.
Synlett 2011, No. 20, 2985–2990 © Thieme Stuttgart · New York