Sciencemadness Discussion Board

Mannich Route -> ephedrines?

flyingbanana - 26-7-2005 at 12:45

Just a thought experiment - Mannich reaction takes place with formaldehyde...what if acetaldehyde were used instead, and on a benzaldehyde? So,

substituted benzaldehyde + CH3CHO + NH(CH3)2 -> the dimethylamino product
methylate and eliminate the amine to get the alkene, then addition of ammonia?

docberto - 26-7-2005 at 14:40

The only reason formaldehyde works in the Mannich reaction is that it doesn't form an enol. Acetaldehyde is in equilibrium with ethenol, so it does not work in the Mannich reaction.

flyingbanana - 26-7-2005 at 15:37

oye! didn't think about that one...oh well, thanks