Zur Synthese der 4-Dialkylamino-5,6-dihydrothiopyran-2-thione

4-Dialkylamino-5,6-dihydrothiopyrane-2-thiones3, 9, 10 are synthesized in good yields by reaction of α,β-unsaturated methylketones with dialkylammonium-dialkyldithiocarbamates5 or carbon disulfide and secondary amines. The reaction takes place via the corresponding oxobutyl-N,N-dialkyldithiocarbamates13 and dialkylaminobutenyl-N,N-dialkyldithiocarbamates14. Cyclohexenylmethylketone11 reacts with5 to give 4-dialkylaminohexahydrothiochromane-2-thiones12. In dimethylformamide or diethyl-formamide as solvents aminolysis take place and 4-dimethylamino or 4-diethylaminothiopyrane-2-thiones are also formed. Instead of 3-alken-2-ones6 also 4-hydroxy-2-alkanones7 and methylketones8 (such as acetone), which readily undergo the aldol condensation can be used for the preparation of thiopyrane-2-thiones.