반응 #1159087

반응 방정식

methyl 2-amino-4-methyl-benzothiazole-5-carboxylate

15-crown-5

tert-butyl nitrite

sodium chloride

→

methyl 2-chloro-4-methylbenzothiazole-5-carboxylate

수율 77.3%

용매

acetonitrile

water

반응 조건

후처리

1. 1
   온도the solution was heated
2. 2
   온도at reflux for 15 h
3. 3
   여과the resulting precipitate was filtered off
4. 4
   농축the solution was concentrated under reduced pressure
5. 5
   추출The residue was then extracted three times with in each case 500 ml of ethyl acetate
6. 6
   온도To this end, the solvent was heated
7. 7
   여과the solution was filtered whilst hot
8. 8
   농축The extracts were concentrated under reduced pressure
9. 9
   기타The residue was purified by trituration with n-hexane/diethyl ether

실험 절차

A solution of 5 g (22.5 mmol) of methyl 2-amino-4-methyl-benzothiazole-5-carboxylate in 2 l of acetonitrile was admixed with 10 ml of water, 4.5 g (44.8 mmol) of copper(I) chloride, 6.6 g of sodium chloride (110 mmol) and 2 ml of 15-crown-5. A solution of 3 g (29 mmol) of tert-butyl nitrite was then added dropwise with stirring, the solution was heated at reflux for 15 h, the resulting precipitate was filtered off and the solution was concentrated under reduced pressure. The residue was then extracted three times with in each case 500 ml of ethyl acetate. To this end, the solvent was heated to boiling point and the solution was filtered whilst hot. The extracts were concentrated under reduced pressure. The residue was purified by trituration with n-hexane/diethyl ether. This gave 4.2 g (17.4 mmol, 77% yield) of methyl 2-chloro-4-methylbenzothiazole-5-carboxylate of m.p. 112° C.

출처