Studies on organophosphorus compounds XX.^† syntheses of thioketones

Substituted benzophenones, 2-benzoylthiophene, 3-benzoylpyridine, dicyclopropyl ketone, and camphor are converted into the corresponding thioketones after reaction with the dimer of p-methoxyphenylthionophosphine sulfide, 1. Except for the pyridine derivatives (2- and 4-benzoylpyridines, respectively, gave no thioketones) very high yields are found. Under the same conditions dibenzylketone gave 1,3-diphenylpropene-2-thiol and 1,9-benzanthr-10-one yielded the dimer of 1,9-benzanthr-10-thione. Aromatic thioketones are also obtained by reacting gem-dichlorides with 2-methyl-2-propane-thiol in the presence of catalytic amounts of CF₃COOH (or AlCl₃). A mechanism is suggested based on kinetic measurements. ¹³C NMR data of the thiocarbonyls of all thioketones are recorded and a function describing the relation between the chemical shifts of CS and CO is found: δ_CS1.57 δ_CO=71.45