3,4-dihydro-2H-pyran → 1-(Tetrahydro-2H-pyran-2-yl)-1H-pyrazole-4-carbonitrile

Participants

Reaction Conditions

Reaction Steps

The reaction was carried out in a 3 liter three-necked flask with internal thermometer under argon. 50 g (537 mmol) of 1H-pyrazole-4-carbonitrile were suspended in 1.66 liter of methylene chloride and, after 3 h, cooled to 3° C. using an ice bath. At this temperature, 10.2 g (53.7 mmol) of 4-toluenesulphonic acid monohydrate were added. At 3° to 6° C., 58.8 ml (54.2 g, 644 mmol) of 3,4 dihydro-2H-pyran were then added dropwise over a period of 30 min. The reaction was then stirred at RT overnight. The clear reaction solution was then washed with 2 M aqueous sodium carbonate solution and with water, dried over magnesium sulphate, filtered and concentrated. The residue was triturated with cyclohexane and the solid obtained was filtered off with suction and dried in a vacuum drying cabinet at 30° C. for 4 h. This gave 91.8 g (96% of theory) of the title compound as a light-yellow powder.

Provenance & Evidence