1,1'-Thiocarbonyldiimidazole → tert-Butyl 8-(cyclopropylmethylene)-2-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[1,5-alpha]pyrazine-7(8H)-carboxylate

Participants

Reaction Steps

A solution of 100 mg (0.28 mmol) of [7-N-(tert-butoxycarbonyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydro [1,2,4]triazolo[1,5-α]pyrazin-8-yl](cyclopropyl)methanol (prepared as outlined in Example 3, Step A), 52.4 mg (0.294 mmol) of 1,1-thiocarbonyldiimidazole, and 3.4 mg (0.028 mmol) of 4-(dimethylamino)pyridine in 2.0 mL of dichloroethane was stirred at reflux temperature for 17 h. The reaction mixture was cooled to ambient temperature and concentrated in vacuo. The residue was partitioned between saturated aqueous sodium bicarbonate solution and ethyl acetate. The aqueous phase was extracted with three portions of ethyl acetate. The combined organics were washed with brine, dried over magnesium sulfate and concentrated. Purification by preparative TLC (silica gel) gave the title compound as a clear semi-solid.

Provenance & Evidence