(Hive Addict)
11-13-03 07:05
No 470658
(Rated as: excellent)
What can you do if you want to reduce an oxime without using NaBH4 / LiAlH4 or BH3 ? There's 3 or 4 standard procedures besides the metal hydrides. Na/EtOH Na/Hg and Al/Hg seem to be dominating the oxime reduction market. Also quite frequently you see Zn used, and I think this is definately an interesting research target as sometimes quite good results are produced. But I stumbled across two other highly interesting procedures:
First one is reduction of 3,4-methylenedioxyphenylacetaldoxime to homopiperonylamine with Ca metal in alcohol. I quote from Patent DE248046:
100 parts of the oxime are dissolved in 2000 parts of alcohol. To this 100 parts Ca are gradually added under reflux cooling. After Ca addition is over the rxn mixtr. is made acidic with HCl and the alcohol distilled. The remaining aquaeous solution is treated with alkali to free the amine which is cleaned by distillation.
Another highly interesting find is only a ref, but it's promising as it could be. Anisaldehyde oxime and a bunch of others are reduced with Pd/C and ammonium formate at room temp and atmospheric pressure in under an hour in MeOH with yields in the 70-85% range.
Kaczmarek, Lukasz; Balicki, Roman; JPCCEM; J.Prakt.Chem./Chem.-Ztg.; EN; 336; 8; 1994; 695-697.
--psyloxy--
"I’d rather be a small part of something great, than a big part of a pile of shit" - Josh Homme
