Synthesis of Thiamono- and Thiabicyclanes from Sodium Sulfide and Methanethiolate.

1-[5-Acetyl-3-(methylthiomethyl)tetrahydro-3-thiopyranyl]-1-ethanone was obtained by the interaction of sodium sulfide and sodium methanethiolate with formaldehyde and acetone. The intramolecular crotonate condensation of the product leads to 4-methyl-1-methylthiomethyl-7-thiabicyclo[3.3.1]non-3-en-2-one. The participation of 3-methylthiomethyl-3-buten-2-one in the formation of a thiamono-cyclane is clarified. A probable scheme for the conversions is proposed.