反应详情

温度

-10 °C

To a solution of the product of step (a) (32.2 g) in ethanol (90 ml) cooled to -10° C. was added ethyl nitrite (18 ml) followed by a solution of sodium ethoxide (from sodium (2.65 g) in ethanol (90 ml)), added dropwise over 90 min. The reaction mixture was then stirred at -10° C. for 16 hours evaporated in vacuo and the residue was dissolved in ethanol (150 ml) and acidified to pH 4.0 by the addition of conc. hydrochloric acid. The resulting solution was evaporated in vacuo and the residue treated with a mixture of ether and ethanol (10:1; 150 ml). Sodium chloride was filtered off and the filtrate evaporated in vacuo to give the oxime as a red oil (23.4 g). The n.m.r. spectrum supported the required structure.

1. additionadded dropwise over 90 min
2. customevaporated in vacuo
3. dissolutionthe residue was dissolved in ethanol (150 ml)
4. additionacidified to pH 4.0 by the addition of conc. hydrochloric acid
5. customThe resulting solution was evaporated in vacuo
6. additionthe residue treated with a mixture of ether and ethanol (10:1; 150 ml)
7. filtrationSodium chloride was filtered off
8. customthe filtrate evaporated in vacuo