Theoretical and experimental study demonstrates kinetic control in chalcone-flavanone transformation of naphthalene derivatives

• Published in: Journal of molecular structure 2018-04, Vol.1157, p.631-637
• Main Authors: Gasque, Laura, Álvarez-Idaboy, J. Raul, Flores-Álamo, Marcos, Guzmán-Méndez, Óscar, Campos-Cerón, Juan M.
• Format: Article
• Language: English
• Subjects: Chalcone; DFT calculations; Flavanone; X-ray structures
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2017.12.078

The condensation of 1′-hydroxy-2′-acetonaphthone with 1- or 2-naphthaldehyde produced the corresponding stable chalcones: C1 or C2. However, the condensation product of either naphthaldehyde with 2′-hydroxy-1′-acetonaphthone yielded chalcones that convert to flavanones- F1 and F2- upon recrystallization. Crystal structures for C1, F1 and F2 are described. Transition state theory estimated rate constants, based on the calculated DFT M052X/6-311 + G(d,p) Gibbs Free energies, show that the rate delimiting step is the cyclization of the chalconate in protic polar solvent. The thermodynamically preferred product is always the flavanone, therefore, the yielding of one or other product is kinetically controlled. [Display omitted] •One isomer of o-hydroxy-acetonaphthone produces a stable chalcone when condensed with 1 or 2-naphthaldehyde.•The other isomer produces chalcones that transform to flavanones during purification.•Crystal structures of one of the chalcones and both flavanones obtained are described.•DFT calculations of Gibbs Free energies allowed to model the reaction mechanism through for several elementary steps.•Calculations show the flavanone formation is favored in all cases, but it is 35 times faster in one case than in the other.