Metaraminol (MA)

Metaraminol, a stereoisomer of meta-hydroxynorephedrine, is a potent sympathomimetic amine used in the prevention and treatment of hypotension, particularly as a complication of anesthesia. It is an α1-adrenergic receptor agonist with some β effect. Metaraminol is also used in the treatment of priapism. Although not approved for this use, it appears to be effective. Metaraminol, L-1-(3-hydroxyphenyl)-2-aminopropan-1-ol, is synthesized in two ways. The first way is synthetic, and it is from 3-hydroxypropiophenone. The hydroxyl group is protected by alkylation with benzyl chloride, giving 3-benzyloxypropiophenone. Upon reaction with butyl nitrite, it undergoes nitrosation into the isonitrosoketone, which by reduction using hydrogen over Raney nickel turns into 1-(3-benzyloxyphenyl)-2-aminopropan-1-ol, the protecting benzyl group is removed by reduction using hydrogen over palladium catalyst, to give racemic metaraminol.