25,3 g (100mmol) 1-(2,4,5-trimethoxyphenyl)-2-nitropropene was suspended in 1000ml IPA or EtOH and 800mg 5%Pd/C was wetted with IPA and added to the suspension. 39g (370mmol) sodium hypophosphite monohydrate was dissolved in 50ml warm water and added in portions to the nitroalkene suspension under violent stirring. The exotherm will easily bring this to a boil, but keep it at 40-50 deg C by immersion in a cold water bath. The reaction is finished when the top alcohol layer is colorless or has just a very slight yellow color left, this takes roughly two hours. Celite was added (three or so teaspoons) and the mixture is stirred for a minute and then filtered at the water pump. The filtrate quickly separates in two layers. The bottom aqueous layer was removed and the top layer was transferred to a rotovap, and the alcohol removed by distillation. This leaves a oil which quickly forms crystals which can either be dissolved in some DCM or toulene, filtered from a small amount of salts and stripped of solvent to give quite pure (98%) oxime and then further reduced to the amine (TMA-2), or the crude oxime can be hydrolysed to the ketone by acid hydrolysis.
Yield 23,4g (98%) 1-(2,4,5-trimethoxyphenyl)-2-propanone oxime
I have performed this reaction for about 6 months now. In the beginning I only got some 70% yield. But now, without having really changed anything, I get 97-98% everytime. Wierd! But I like it..