Hydrochloric Acid → 4-Hydroxy-4-(thiazol-5-yl)cyclohexanone

Participants

Reaction Conditions

Reaction Steps

A 5-L 4-neck round bottom flask equipped with a thermocouple, a mechanical stirrer, a condenser, and a nitrogen inlet/outlet adapter was charged with ketal 9 as prepared in the previous step (316.3 g, 1.30 mol) and DMF (238.0 mL) with stirring. A solution of 2 N HCl (1.13 L, 2.26 mol) was added over 2 min; the mixture was stirred at 26° C. for 5 min, warmed up to 60° C., and stirred for 3 h. The progress of the reaction was monitored by HPLC and LC-MS. The reaction was cooled to 0° C. in an ice-water bath, and the aqueous (pH=2˜3) was adjusted to an alkaline (pH=10˜11) by dropwise addition of 4 N NaOH solution with fast agitation. The resulting alkaline slurry was stirred at 0° C. for 1 h; the solid was collected by filtration, washed with cold water (100 mL), dried under air-suction for 1 h, and then placed in a vacuum drying oven under house vacuum (120 mmHg) at 50° C. for 48 h to afford the title compound, 10 as a beige crystalline solid.

Provenance & Evidence