反应详情

A preferred synthesis of the desired product acylated aminosalicylamides (Formula I) is shown in the following Scheme 1. 2-Hydroxy-3-nitrobenzoic acid 1 was converted to the acid chloride 2 with excess thionyl chloride. After removal of the excess thionyl chloride, the crude acid chloride 2 was reacted with the desired cyclic amine 3 in dichloromethane solution containing triethylamine as an acid scavenger and 4-dimethylaminopyridine (DMAP) as a catalyst. Crude 3-nitrosalicylamide 4 could be isolated after washing the reaction mixture with dilute HCl solution, drying, and evaporation of the solvent. Usually 4 was of sufficient purity to carry forward to the final product 6, but if desired could be purified by recrystallization or chromatography or a combination of both. In some cases where the 3-nitrosalicylamide 4 is a mixture of diastereomers, one might choose to isolate the individual diastereomers at this stage. However, since all of the various diastereomers are fuigicidally active, this is not necessary. The 3-nitrosalicylamide (4) was subsequently reduced under catalytic hydrogenation conditions using Pd, Pt, or Ni catalysts either unpoisoned or poisoned with sulfur or lead. The 3-aminosalicylamide 5 usually was not isolated, but immediately reacted with excess acetic-formic anhydride. Isolation of the AASA product 6 was a simple matter of filtration, washing with sodium bicarbonate solution, drying and evaporation of the solvent The crude product 6, usually a solid foam or glass, often was of sufficient purity to be directly submitted for testing. However, if desired, it could be further purified by recrystallization or chromatography or a combination of both.

1. customAfter removal of the excess thionyl chloride
2. customthe crude acid chloride 2 was reacted with the desired cyclic amine 3 in dichloromethane solution
3. customCrude 3-nitrosalicylamide 4 could be isolated
4. washafter washing the reaction mixture with dilute HCl solution
5. customdrying
6. customevaporation of the solvent
7. customif desired could be purified by recrystallization or chromatography
8. additiona mixture of diastereomers, one
9. customto isolate the individual diastereomers at this stage