Broxaterol

Broxaterol is a β2 adrenoreceptor agonist. It is part of a class of drugs that affect the smooth muscle receptors in the body, often in use cases for respiratory disease that respond to this type of treatment.

Synthesis

 * Broxaterol synthesis cycloaddition.svg

The 1,3-dipolar cycloaddition between bromonitrile oxide, produced in situ from dibromoformaldoxime, and 3-butyn-2-one gives a mixture of isoxazoles, mainly the isomer shown required for broxaterol. Selective α-bromination of the acetyl group with pyridinium tribromide gives a bromoketone whose carbonyl group is reduced with sodium borohydride to produce a bromoethanol derivative. Treatment of this with tert-butylamine yields broxaterol.