Studies on organophosphorus compounds XX. syntheses of thioketones

Abstract

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