A Study of the Chemistry of Thietan-3-Ones and Related Substances

Abstract

The chemistry of some novel derivatives of thietan—3-ones has been studied. These thietanones have been prepared by the treatment of certain ketones with thionyl chloride in the presence or absence of pyridine. The stereochemistry of the thietanones was studied using nuclear magnetic resonance spectroscopy. The intermediates found during the formation of the thietanones have been shown to be the β-ketosulfinyl chlorides or the β-ketosulfenyl chloride depending on the nature of the ketone. A certain new compounds, dithiolanone and thiolanone were synthesized by the treatment of dibramoketones with sodium sulfide and by the treatment of the β-ketosulfinyl chlorides with thionyl chloride respectively. Cyclization of the β-ketosulfenyl chlorides and β-ketosulfinyl chlorides was attempted using pyridine or triethylamine. The nucleophilic reactions of the chlorothietanones have been studied using pyrrolidine, morpholine, piperidine, methanol, benzylmercaptan and hydrazine derivatives. The hydrazine derivatives have been shown to attack both the C-2 and C-3 carbon of the thietanone. The other nucleophiles used only attack the C-2. When water is used as the nucleophile, carbon-sulfur cleavage occurs. It was found that the case of the nucleophilic reactions of the chlorothietanone may be correlated with the basicities and the sp2 character of carbon -2. The reduction of the 2-chlorothietanone was investigated using different reducing reagents. Treatment of the thietanone with sulfuryl chloride was shown not only to chlorinate the former but also to cleave the carbon-sulfur bond of the thietanone. Treatment of the benzylidenethietanone with thionyl chloride did not give a dichloro-adduct as previously reported. In fact the product was found to be α- chloro-β-chloro rchlorosulfenyl thietanone. The mechanism of the reactions has been studied and discussed using both chemical and spectroscopic evidence.