Sodium Hydroxide → HCID 86757621, compound

Participants

Reaction Steps

Under an atmosphere of protective gas and at 20 to 25° C., 2.6 ml (4.11 mmol) of n-butyllithium in hexane (1.6 molar) were rapidly added dropwise to 0.86 g (4.11 mmol) of 4-bromo-5-chloro-1-ethylpyrazole in 30 ml of diethyl ether. The mixture was stirred at room temperature for 15 minutes and the resulting suspension was then, at −70° C., added dropwise to a solution of 2.2 g (8.21 mmol) of 4,4,8-trimethyl-1,1-dioxothiochroman-7-carbonyl chloride in 30 ml of diethyl ether. The reaction mixture was subsequently warmed to room temperature and mixed with 11 ml of methanol and 26 ml of 2N aqueous sodium hydroxide solution. The organic phase was then separated off, dried and concentrated and the residue was chromatographed over silica gel (mobile phase: ethyl acetate/cyclohexane=3/2).

Provenance & Evidence