4-Toluenesulfonyl chloride → Nopol tosylate

Participants

Reaction Conditions

Reaction Steps

A dry, 2-L flask equipped with a septum inlet, magnetic stirring bar, and a reflux condenser leading to a mercury bubbler was flushed with dry nitrogen and maintained under static pressure of nitrogen. The flask was charged with 170 mL (1 mol) of (-)-nopol [[α]23D 40.2 (neat)] and 400 mL tetrahydrofuran (THF) and cooled to -78° C. While the solution was stirring at -78° C., 455 mL (2.2M, 1 mol) of n-BuLi was added slowly and stirred for 1 h at -78° C.; 190 g (1 mol) of p-toluenesulfonyl chloride in 200 mL of THF was added slowly and the stirring continued for another hour at at -78° C. It was then warmed to room temperature and stirred for 2 h. The reaction mixture was poured into ice-water and extracted with pentane. Evaporation of the solvent gave a thick semi-solid of nopol tosylate in 90% yield (290 g). Nopol tosylate (290 g) was dissolved in hot pentane (800 mL) and stored at 0° C. for 12 h to insure complete crystallization. Colorless white needles of Nopol tosylate (mp 50°-51° C.) were recovered by fast filtration in 85% yield.

Provenance & Evidence