The 2,4-dibromobutyrylchloride (I) was reacted with N-methylhydroxylamine (II) in methylene chloride with NaOH to yield 4-bromo-2-methyl-5,6-dihydro-2H-1,2-oxazin-3(4H)-one (III). The reaction of (III) and zinc with 3,5-di-tert-butyl-4-hydroxybenzaldehyde (IV) underwent Reformatsky-type reaction. Dehydration of the hydroxymethyl intermediate (V) in refluxing toluene with p-toluenesulfonic acid afforded BF-389.