This work was supported financially by the Xunta de Galicia
(projects CN 2012/184 and the Galician Network on Ionic
Liquids (REGALIs2 (Axuda R2014/015)). The work of the
NMR, SC-XRD and MS divisions of the research support
services of the University of Vigo (CACTI) is also gratefully
acknowledged. A.F; O.D.; M.G and M.S. thank the University
Cheikh Anta Diop (Dakar) for financial support for a research
stay at the University of Vigo. I.S and M.S. thank the Senegalese
Ministry of Scientific Research : FIRST (fonds d'impulsion de la
recherche scientifique et technique) for a research grant.
at room temperature for 5 h. Ether (1 mL) was added, the
organic phase was decanted, rotatory evaporated and the residue
chromatographed on silica gel, affording a 70% yield of the
expected compound 20. We then carried out the same reaction
using ethyl acrylate (21) or acrylonitrile (23) and were delighted
to see that the MBH occurred smoothly giving 80 and 88% yield
respectively (Scheme 4)
References and notes
1.
(a) Baylis, A. B.; Hillman, M. E. D. Ger. Offen. 2, 155, 113, 1972;
Chem. Abstr. 1972, 77, 34174q; Hillman, M. E. D.Baylis, A. B.
U.S. Patent3, 743, 669, 1973; (b) Morita, K.; Suzuki, Z.; Hirose,
H. Bull. Chem. Soc. Jpn. 1968, 41, 2815-2815. For reviews on
MBH reaction, see: (c) Basavaiah, D.; Rao, A. J.; Satyanarayana,
T. Chem. Rev. 2003, 103, 811-892; (d) Basavaiah, D.; Rao, K. V.;
Reddy, R. J. Chem. Soc. Rev. 2007, 36, 1581-1588; (e) Singh, V.;
Batra, S. Tetrahedron Lett. 2008, 64, 4511-4574; (f) Wei, Y.; Shi,
M. Acc. Chem. Res. 2010, 43, 1005-1018; (g) Wei, Y.; Shi, M.
Chem. Rev. 2013, 113, 6659-6690.
2.
3.
4.
5.
6.
7.
(a) Kim, H. S.; Kim, T. Y.; Lee, K. Y.; Chung, Y. M.; Lee, H. J.;
Kim, J. N. Tetrahedron Lett. 2000, 41, 2613-2616; (b)
Junior, C. G. L.; Vasconcellos, M. L. A. A. Bioorg. Med. Chem.
2012, 20, 3954-3971.
Aggarwal, V. K.; Mereu, A.; Tarver, G. J.; McCague, R. J. Org.
Chem. 1998, 63, 7183-7189.
Kundu, M. K.; Mukherjee, S. B.; Balu, N.; Padmakumar, R.; Bhat,
S. Synlett 1994, 6, 444-444.
Roos, G. H. P.; Rampersadh, P. Synth. Commun. 1993, 23, 1261-
1266.
(a) Rosa, J. N.; Afonso, C. A. M.; Santos, A. G. Tetrahedron
2001, 57, 4189-4193; (b) Aggarwal, V. K.; Emme, I.; Mereu, A.
Chem. Commun. 2002, 1612-1613; For recent reviews, see (c) T.
Welton Chem. Rev. 1999, 99, 2071-2083. (d) P. Wasserscheid, W.
Keim Angew. Chem., Int. Ed. 2000, 39, 3772-3789; (e) J. S.
Wilkes Green Chem. 2002, 4, 73-80; (f) J. Dupont, R. F. de
Souza, P. A. Z. Suarez, Chem. Rev. 2002, 102, 3667-3691; (g) P.
Wasserscheid, T. Welton Ionic Liquids in Synthesis; Wiley-VCH:
Weinheim, Germany, 2003.
Scheme
4.
Morita-Bylis-Hillman
reaction
of
p-
chlorobenzaldehyde 18 and vinyl ketone (19) ethyl acrylate (21)
and acrylonitrile (23) in 1,3,4-trialkyl-1,2,3-triazolium ionic
liquid 13b.
Recent mechanistic studies of the MBH reaction have put some
light on the rational behind the rate-determining step
(RDS).10Taking into account the concept of hydrogen bonding
we may explain the rate enhancement of our ILs by the presence
of the hydroxyl groups in the side chain (Scheme 5).
8.
9.
For a previous synthesis of 1,3-Dialkyl-1,2,3-triazolium ionic
liquids and their application to the MBH reaction, see: J.
Yunkyung, R. J-S. J. Org. Chem. 2010, 75, 4183-4191.
(a) H. C. Kolb, M. G. Finn, K. B. Sharpless Angew. Chem., Int.
Ed. 2001, 40, 2004-2021; (b) V. V. Rostovtsev, L. G. Green, V. V.
Fokin, K. B. Sharpless, Angew. Chem., Int. Ed. 2002, 41, 2596-
2599; (c) C. W. Toroe, M. Christensen, M. Meldal J. Org. Chem.
2002, 67, 3057-3064; (d) A. Krasiñski, V. V. Forkin, K. B.
Sharpless Org. Lett. 2004, 6, 1237-1240; (e) T. Thirumurugan, D.
Matosiuk, K. Jozwiak Chem. Rev. 2013, 113, 4905-4979.
10. (a) D. Cantillo, C. O. Kappe J. Org. Chem. 2010, 75, 8615-8626;
T. S. Rodrigues, V. H. C. Silva, P. M. Lalli, H. C. B. de Oliveira,
W. A. da Silva, F. Coelho, M. N. Eberlin, B. A. D. Neto J. Org.
Chem. 2014, 79, 5239-5248; R. E. Plata, D. A. Singleton J. Am.
Chem. Soc. 2015, 137, 3811-3826.
Scheme 5. Mechanism of the MBH in IL medium
In summary, we have synthesized a series of new triazolium-
based ionic liquids which have been successfully used as reaction
media for the Morita-Bylis-Hillman (MBH) reaction. Work is
now in progress for the study of the scope and limitations of this
reaction. The application of the obtained ionic liquids to other
important organic reactions is also underway in our laboratory.
Acknowledgments