Determination of enol form of asymmetric 1,3-dicarbonyl compounds: 2D HMBC NMR data and DFT calculations
Main Article Content
Abstract
In this study, a series of asymmetric aryl 1,3-dicarbonyl compounds were synthesized and their enol forms were observed via experimental data and theoretical calculations. According to the 1H- and 13C-NMR results, all the investigated compounds were found as a single enol form in CDCl3 solution. Moreover, their HMBC spectra were applied to identify the observed enol forms and correlations between certain protons and carbon atoms were considered. The dihedral angles of the asymmetric compounds that have aryl units on both sides were calculated by DFT to understand the reason for the observed enol forms. Small dihedral angles caused longer conjugation, resulting in more stable compounds and it was found that the observed enol forms were based on small dihedral angles, namely, resonance is the driving force. Furthermore, the compounds possessing both aryl and alkyl moieties prefer the enol form towards the aromatic ring side due to longer conjugation.
Downloads
Metrics
Article Details
Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution license 4.0 that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
References
E. D. Raczynska, W. Kosinska, B. Osmialowski, R. Gawinecki, Chem. Rev. 105 (2005) 3561 (https://doi.org/10.1021/cr030087h)
S. Karabulut, H. Namlı, J. Mol. Struct. 1024 (2012) 151 (https://doi.org/10.1016/-j.molstruc.2012.05.029)
C. M. Yvonne, J. Com¬put.-Aided Mol. Des. 23 (2009) 693 (https://doi.org/10.1007/¬s10822-009-9303-2)
a) D. J. Kuo, I. A. Rose, J. Am. Chem. Soc. 100 (1978) 6288 (https://doi.org/10.1007/s10822-009-9303-2); b) D. J. Kuo, E. L. OConnell, I. A. Rose, J. Am. Chem. Soc. 101 (1979) 5025 (https://doi.org/10.10¬21/ja00511a037); c) D. J. Kuo, I. A. Rose, J. Am. Chem. Soc. 104 (1982) 3235 (https://doi.org/10.10-21/ja00375a058); d) S. J. Grabowski, T. M. Krygowski, B. Stepien, J. Phys. Org. Chem. 13 (2000) 740 (https://doi.org/10.1002/1099-1395(200011)13:11<740::AID-POC304>¬3.0.CO;2-1)
a) L. Claisen, Liebigs Ann. Chem. 291 (1896) 25 (https://doi.org/10.1002/jlac.1896¬2910106); b) W. L. Wislicenus, Liebigs Ann. Chem. 291 (1896) 147 (https://doi.org/¬10.1002/jlac.18962910108); c) L. Knorr, Liebigs Ann. Chem. 293 (1896) 70 (https://doi.¬org/10.1002/jlac.18962930107)
J. Zawadiak, M. Mrzyczek, Spectrochim. Acta, A 75 (2010) 925 (https://doi.org/10.1016/j.saa.2009.12.040)
J. Zawadiak, M. Mrzyczek, Spectrochim. Acta, A 96 (2012) 815 (https://doi.org/10.1016/j.saa.2012.07.109)
S. F. Tayyari, F. Naghav, S. Pojhan, R. W. McClurg, R. E. Sammelson, J. Mol. Struct. 987 (2011) 241 (https://doi.org/10.1016/j.molstruc.2010.12.034)
W. C. Plessis, T. G. Vosloo, J. C. Swarts, J. Chem. Soc., Dalton Trans. 15 (1998) 2507 (https://doi.org/10.1039/A802398K)
W. C. Plessis, J. J. C. Erasmus, G. J. Lamprecht, J. Conradie, T. S. Cameron, M. A. S. Aquino, J. C. Swarts, Can. J. Chem. 77 (1999) 378 (https://doi.org/10.1139/v99-015)
W. C. Plessis, W. L. Davis, S. J. Cronje, J. C. Swarts, Inorg. Chim. Acta 314 (2001) 97 (https://doi.org/10.1016/S0020-1693(01)00292-4)
J. Berger, L. A. Flippin, R. Greenhouse, S. Jaime-Figueroa, Y. Liu, A. K. Miller, D. G. Putman, K. K. Weinhardt, S. H. Zhao, US, 5.863.924 (1999)
A. Rojas, A. Perez-Encabo, I. Herraiz-Sierra, C. A. Blanco, Can. J. Chem. 79 (2001) 448 (https://doi.org/10.1139/v01-061)
A. Nekoei, S. F. Tayyari, M. Vakili, S. Holakoei, A. H. Hamidian, R. E. Sammelson, J. Mol. Struct. 932 (2009) 112 (https://doi.org/10.1016/j.molstruc.2009.05.045)
M. A. Dobrowolski, M. K. Cyranski, Z. Wrobel, Phys. Chem. Chem. Phys. 18 (2016) 11813 (https://doi.org/10.1039/c5cp07056b)
A. D. Becke, J. Chem. Phys. 98 (1993) 5648 (https://doi.org/10.1063/1.464913)
C. Lee, W. Yang, R. G. Parr Yang, Phys. Rev. B: Condens. Matter Mater. Phys. 37 (1988) 785 (https://doi.org/10.1103/PhysRevB.37.785)
Gaussian 09, Revision B.01, Gaussian, Inc., Wallingford CT, 2010
S. Miertus, E. Scrocco, J. Tomasi, Chem. Phys. 55 (1981) 117 (https://doi.org/-10.1016/0301-0104(81)85090-2)
J. Tomasi, B. Mennucci, R. Cammi, Chem. Rev. 105 (2005), 2999 (https://doi.org/¬10.1016/0301-0104(81)85090-2)
S. Miao, S. M. Brombosz, P. R. Schleyer, J. J. Wu, S. Barlow, S. R. Marder, K. I. Hardcastle, U. H. F. Bunz, J. Am. Chem. Soc. 130 (2008) 7339 (https://doi.org/10.1016/0301-0104(81)85090-2)
H. Cheema, A. Peddapuram, R. E. Adams, L. McNamara, L. A. Hunt, N. Le, D. L. Watkins, N. I. Hammer, R. H. Schmehl, J. H. Delcamp, J. Org. Chem. 82 (2017) 12038 (https://doi.org/10.1021/acs.joc.7b01750)
S. Gümüş, N. Aslan, N. N. Büyükadalı, A. Gümüş, Tetrahedron: Asymmetry 28 (2017) 479 (https://doi.org/10.1016/j.tetasy.2017.02.014)
F. Milletti, A. Vulpetti, J. Chem. Inf. Model. 50 (2010) 1062 (https://doi.org/10.1021/ci900501c).