RSC Advances
Communication
a,b-Unsaturated ynones are another family of interesting
substrates for the 1,4-addition reaction (eqn (2)). This is exem-
plied by MW-assisted reaction of 4-phenylbut-3-yn-2-one (8a).
Specically, treatment of 8a in an aqueous solution containing
20 mol% TBA-OH results in the formation of a mixture of 1,3-
diketone 9a (30%), acetophenone (2b, 11%), and substituted
phenol 10a (10%). The structure of 10a was determined by using
COSY, HMBC, HSQC 2D NMR spectroscopy (See the ESI†). In
addition to this result, the microwave-assisted reaction of 8a
with 9a by TBA-OH catalyst in aqueous condition produced a
mixture of substituted phenol 10a (93%) and o-alkylated phenol
11a (5%), generated by butylation of 10a with TBA-OH. The o-
alkylated phenol 11a was converted into substituted phenol 10a
by 10 mol% of AlCl3 in MeOH for 2 h (eqn (3)).10 It is reasonable
to speculate that the 1,3-diketone 9a is generated by 1,4-addi-
tion of water followed by tautomerization (Scheme 3). And 2b
comes from 9a by retro-Claisen cleavage.11 In addition, phenol
derivative 10a is likely formed by Robinson annulation between
1,3-diketone 9a with ynone 8a occurring via intermediates 12a
and 13a. To conrm this proposal, a mixture of 8a and 9a in
H2O was MW-heated at 100 ꢀC for 10 min in the presence of
TBA-OH followed by treatment with AlCl3 in MeOH. This
process led to formation of 10a in a 90% (Table 4, entry 1). The
generality of the MW-assisted reactions of a,b-unsaturated
ynones, which take place much more efficiently than those
induced by using conventional heating,12 was demonstrated by
the examples displayed in Table 4 (entries 2–7). And they
produced 2,3,5-trisubstituted phenols in good to moderate
yields.
3 (a) C. J. Adams, M. J. Earle, G. Robert and K. R. Seddon,
Chem. Commun., 1998, 19, 2097; (b) J. Dupont, R. F. de
Souza and P. A. Z. Suarez, Chem. Rev., 2002, 102, 3667.
4 (a) W. Leitner, Acc. Chem. Res., 2002, 35, 746; (b)
E. J. Beckman, J. Supercrit. Fluids, 2004, 28, 121.
¨
5 (a) U. M. Llindstrom, Chem. Rev., 2002, 102, 2751; (b)
T. Okuhara, Chem. Rev., 2002, 102, 3641; (c) R. A. Sheldon,
Green Chem., 2005, 7, 267; (d) C. Liu, Y. Zhang, N. Liu and
J. Qiu, Green Chem., 2012, 14, 2999.
6 (a) C. O. Kappe, Angew. Chem., Int. Ed., 2004, 43, 6250; (b)
D. Bogdal and A. Loupy, Org. Process Res. Dev., 2008, 12,
710; (c) B. Rissa, A. E. Louzi, A. Loupy, A. Petit,
´
M. Souaoui and S. F. Tetouani, Eur. J. Org. Chem., 2002,
15, 2518; (d) A. Loupy, M. Pellet, A. Petit and G. Vo-
Thanh, Org. Biomol. Chem., 2005, 3, 1534; (e) H. Lee,
Y.-K. Sim, J.-W. Park and C.-H. Jun, Chem.–Eur. J., 2014,
20, 323.
7 (a) J. Schmidt, C. Ehasz, M. Epperson, K. Klas, J. Wyatt,
M. Hennig and M. Forconi, Org. Biomol. Chem., 2013, 11,
8419; (b) A. M. Frey, S. K. Karmee, K. P. de Jong, J. H. Bitter
and U. Hanefeld, ChemCatChem, 2013, 5, 594; (c)
Y. V. Pfeifer, P. T. Haase and L. W. Kroh, J. Agric. Food
Chem., 2013, 61, 3090; (d) R. M. Archer, S. F. Royer,
W. Mahy, C. L. Winn, M. J. Danson and S. D. Bull, Chem.–
Eur. J., 2013, 19, 2895; (e) T. Honma and H. Inomata, J.
Supercrit. Fluids, 2014, 90, 1.
8 (a) Y. Kondo, K. Kon-I, A. Iwasaki, T. Ooi and K. Maruoka,
Angew. Chem., Int. Ed., 2000, 39(2), 414; (b) K. Kobiro, J.
Fudan Univ., Nat. Sci., 2005, 44(5), 701; (c) H. Chen, H. Ji,
X. Zhou and L. Wang, Tetrahedron, 2010, 66, 9888; (d)
N. Anand, K. H. P. Reddy, K. S. R. Rao and D. R. Burri,
Catal. Lett., 2011, 141, 1355; (e) X. Chen, K. Sumoto,
S. Mitani, T. Yamagami, K. Yokoyama, P. Wang, S. Hirao,
N. Nishiwaki and K. Kobiro, J. Supercrit. Fluids, 2012, 62,
178; (f) D. Enders and T. V. Nguyen, Tetrahedron Lett.,
2012, 53, 2091; (g) D. Azarifar and Z. Najminejad, Synlett,
2013, 24(11), 1377.
Conclusions
In the effort described above, we developed an eco-friendly,
TBA-OH catalysed, microwave-assisted method for efficient 1,4-
addition of water to a,b-unsaturated ketones and a,b-ynones.
The observed C–C double bond cleavage reactions of a,b-enones
and annulation reactions of a,b-ynones take place with high
efficiencies in pure aqueous solutions. Efforts directed at
developing applications of this ‘Green Chemistry’ method to the
synthesis of important targets are progressing.
9 (a) C. Ivanov and T. Tcholakova, Synthesis, 1981, 5, 392; (b)
G. A. Kraus, H. Cho, S. Crowley, B. Roth, H. Sugimoto and
´
S. Prugh, J. Org. Chem., 1983, 48, 3439; (c) E. T. Oganesyan,
A. V. Pyshchev and L. I. Butenko, Pharm. Chem. J., 1999,
´
33(9), 480; (d) D. Tejedor, G. Mendez-Abt, L. Cotos,
´
Acknowledgements
M. A. Ramirez and F. Ga1qrcıa-Tellado, Chem.–Eur. J.,
2011, 17, 3318.
This work was supported by a grant from the National Research
Foundation of Korea (NRF) (2011-0016830).
10 The formed o-alkylated phenol is converted into dealkylated
phenol under the AlCl3 in MeOH conditions, according to
the followed reference: V. V. Namboodiri and R. S. Varma,
Tetrahedron Lett., 2002, 43, 1143
Notes and references
1 (a) R. A. Sheldon, J. Mol. Catal. A: Chem., 1996, 107, 75; (b)
P. T. Anastas and J. C. Warner, Green Chemistry: Theory and
Practice, Oxford University Press, New York, 1998, p. 30; (c)
M. poliakoff and P. Licence, Nature, 2007, 450, 810; (d)
P. T. Anastas and I. T. Hovarsth, Chem. Rev., 2007, 107, 2169.
2 (a) K. Tanaka and F. Toda, Chem. Rev., 2000, 100, 1025; (b)
G. Rothenberg, A. P. Downie, C. L. Raston and J. L. Scott, J.
Am. Chem. Soc., 2001, 123, 8701.
11 (a) R. G. Pearson and E. A. Mayerle, J. Am. Chem. Soc., 1951,
73, 926; (b) Y. M. A. Yamada and Y. Uozumi, Tetrahedron,
48334 | RSC Adv., 2014, 4, 48331–48335
This journal is © The Royal Society of Chemistry 2014