合成路线1

A new method for the synthesis of pirbuterol hydrochloride has been described: By reaction of 2-phenyl-4H-1,3-dioxino[5,4-b]pyridine-6-carbaldehyde (I) with methyltriphenylphosphonium bromide (II) and NaOH in toluene to give 2-phenyl-6-vinyl-4H-1,3-dioxino[5,4-b]pyridine (III), which is treated with m-chloroperbenzoic acid (IV) in methylene chloride to give 6-(1,2-epoxyethyl)-2-phenyl-4H-1,3-dioxino[5,4-b]pyridine N-oxide (V). Compound (V) can also be obtained from 6-(1,2-epoxyethyl)-2-phenyl-4H-1,3-dioxino[5,4-b]pyridine (VI) by reaction with m-chloroperbenzoic acid (IV) as before. The reaction of (V) with tert-butylamine (VII) in methanol affords 6-(1-hydroxy-2-tert-butylaminoethyl)-2-phenyl-4H-1,3-dioxino[5,4-b]pyridine N-oxide (VIII), which is first treated with H2 over Pd/C in methanol and then with HCl in ethyl acetate to give pirbuterol hydrochloride.