Sodium peroxyborate tetrahydrate → Ethyl 2-sulfo-1-cyclohexene-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

Sodium peroxyborate tetrahydrate (74.3 g) was admixed with acetic acid (400 ml) and heated to 50 to 55° C. and then a solution of ethyl 2-mercapto-1-cyclohexene-1-carboxylate (30.0 g) in acetic acid (50 ml) was added dropwise over 2 hours. The mixture was stirred at 50 to 55° C. for 3 hours and then at 80 to 85° C. for 5 hours and concentrated under reduced pressure. The residue was combined with acetonitrile (660 ml) and stirred at room temperature for 1 hour and the resultant insolubles were filtered off. The insolubles were washed with acetonitrile (50 ml) and the filtrate and the washing were combined and concentrated under reduced pressure, and the resultant residue was dissolved in acetonitrile (500 ml) and stirred at room temperature for 2 hours. The resultant insolubles were filtered off, and the filtrate was concentrated under reduced pressure. The residue was combined with diisopropyl ether (1000 ml) and the powder which precipitated was isolated by filtration to obtain ethyl 2-sulfo-1-cyclohexene-1-carboxylate as a white powder (55 g) containing inorganic substances. This was treated dropwise with thionyl chloride (150 ml) at 0° C. over 1 hour and then stirred at 80 to 85° C. for 20 hours. The mixture was evaporated under reduced pressure to dryness and the residue was partitioned between ethyl acetate (300 ml) and a dilute brine (400 ml) and the aqueous layer was extracted with ethyl acetate (200 ml). The ethyl acetate layers were combined and washed with saturated brine (200 mL) and dried over anhydrous sodium sulfate. The solvent was evaporated off to obtain a residue, which was purified by flash chromatography on silica gel column (eluent: ethyl acetate/hexane=1/8→ethyl acetate/hexane=1/5) to yield ethyl 2-chlorosulfonyl-1-cyclohexene-1-carboxylate (21.5 g) as yellow crystals.

Provenance & Evidence