Synthesis of chalconoid like compounds and their [2+2] photodimerizations in solution and theoretical calculations

SUMMARY Synthesis of Chalconoid Like Compounds and Their [2 + 2] Photodimerizations in Solution and Theoretical Calculations In the first part of this work, four different chalconoid-like compounds were synthesized according to Claisen-Schmidt reactions. In the second part of the study, the synthesized chalconoid-like compounds were exposed to UV light to give photochemical dimerization reaction products. The structures of the synthesized monomers and dimers were identified. In addition, the energy of the possible 1 1 isomers of the synthesized compounds was calculated with Hyperchem software. The stabilities of these kinetically possible 1 1 isomers were calculated with both semi-empirical and molecular mechanical methods. The calculations showed the thermodynamically most stable product to be the experimental product the structure of which was identified by all the spectroscopic methods utilized. The kinetical stability of the reaction was investigated with Hyperchem program, and it was concluded that the main products of the photodimerization were formed by head-to-head addition reaction, which was in accordance with experimental findings. The structures of the synthesized compounds were identified by nuclear magnetic resonance spectroscopy (200 MHz NMR, ID: !H, 13C, DEPT, APT; and 2D: COSY, HETCOR, NOESY), Fourier-transform-infra-red (FT-IR) spectroscopy, ultraviolet absorption spectroscopy (UV), and liquid chromatography-tandem mass spectrometry (LC- MS/MS) techniques. Keywords: Chalconoids, alnustone, photodimerizations, dimers, theoretical calculations VI