1,2-Ethanedithiol → Ammonia

Participants

Reaction Steps

A solution of 0.5 g 2,8-dimethyl-1-oxa-8-azaspiro[4,5]-decan-3-one in 10 ml dichloromethane was cooled in ice, 0.45 ml 1,2-ethanedithiol was added, and 2 ml boron trifluoride/ether complex was then added dropwise while maintaining the temperature below 10° C. After stirring at that temperature for one hour, the reaction mixture was poured into 30 ml of 20% aqueous caustic soda solution. The insoluble matters were filtered off, the filtrate was extracted with ethyl acetate, and the organic layer was washed with saturated aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate. The dried solution was concentrated under reduced pressure, and the residue was subjected to silica gel column chromatography using, as eluent, a mixed solvent of chloroform/methanol/conc. ammonia (20:1:0.1 by volume), giving 0.46 g of 10,14-dimethyl-13-oxa-1,4-dithia-10-azadispiro[4,1,5,2]tetradecane. It was dissolved in methanol and converted to maleate by addition of an equimolar amount of maleic acid dissolved in the same solvent.

Provenance & Evidence