QUANTUM-CHEMICAL STUDY OF POSSIBLE STRUCTURAL TRANSFORMATIONS IN 3-METHYLTHIO-3-PHENYL-2-PROPENETHIAL

The plausible formation of 3-methylthio-1-phenyl-2-propene-1-thione an d 3-methylthio-3-phenyl-2-propenethial in the reaction of ethylthio-3- phenyl-2-propene-1-N,N-dimethyliminium iodide with hydrogen sulfide wa s shown in the framework of semiempirical AM1 and PM3 methods. In pola r media, these products can be trimerized into four types of structure s. The kind of trimer depends on the shift of the equilibrium in the 3 -methylthio-3-phenyl-2-propenethial reversible arrow 3-methylthio-1-ph enyl-2-propene-1-thione mixture. Each of the four types of trimers is characterized by the presence of three nearly planar six-membered pseu do-chelate rings. The possibility of obtaining derivatives of 1,2-dith iolane (the basic fragment of lipoic acid) from the reaction products in nonpolar solvents was considered.