反应详情

A solution of 4-(4-aminophenyl)-1-piperazinecarboxylic acid, 1,1-dimethylethyl ester (15 g, 54.1 mmol) (from Step B above) in N,N-dimethylformamide (120 mL) was added dropwise to a cooled (−15° C.) solution of 1,1′-thiocarbonyldiimidazole (9.66 g, 54.2 mmol) (Aldrich) in N,N-dimethylformamide (40 mL). After the addition was complete, the cooling bath was removed and the solution was stirred for 1 h. The mixture was poured into ice-water (1 L), stirred for 30 minutes, and extracted with diethyl ether. The combined extracts were dried over Na2SO4, and evaporated in vacuo to provide 4-(4-isothio-cyanatophenyl)-1-piperazinecarboxylic acid, 1,1-dimethylethyl ester (18 g, 94%).

1. additionAfter the addition
2. customthe cooling bath was removed
3. additionThe mixture was poured into ice-water (1 L)
4. stirringstirred for 30 minutes
5. extractionextracted with diethyl ether
6. dry with materialThe combined extracts were dried over Na2SO4
7. customevaporated in vacuo