Hexane → p-Toluenesulfonate

Participants

Reaction Steps

The product of Example 447A (11.1 g, 40 mmol) in THF (60 mL) was treated with a solution of sodium cyanoborohydride (5.3 g, 80 mmol) in THF (30 mL) dropwise at 5° C. over 15 minutes, then 5° C. for 3 hours and at room temperature for 3 days. The reaction was quenched with 1N HCl (to pH 1) and stirred at room temperature for 3 hours, adjusted to pH 11 with K2CO3, and then extracted with ethyl acetate (100 mL). The organic layer was washed with water (3×50 mL) and brine, dried over MgSO4, concentrated and dried at room temperature in vacuum to give crude product (10.2 g) as colorless liquid. The obtained crude product was diluted with i-PrOH (71 mL), treated with p-toluenesulfonic acid monohydrate (7.05g, 37 mmol), and then the mixture was heated to reflux. n-Hexane (71 mL) was added to the hot solution, and then the solution was cooled to room temperature gradually and stirred at room temperature for 2 hours. The resulting crystal was collected by filtration, washed with a mixture of i-PrOH and n-hexane (1:1), and dried at 40° C. overnight in vacuum to give the title compound as tosylate (colorless crystal, 9.3 g): yield 52% from 2,2,2-trifluoroacetophenone

Provenance & Evidence