The low-valent Fe-complex Bu₄N[Fe(CO)₃(NO)] (TBA[Fe]) catalyzes the reductive cleavage of N-O-bonds in oxazines under salt-free conditions using malononitrile as reductant. The mild reduction conditions allow the development of a sequence of [4 + 2]-cycloaddition/reductive cleavage, a process that can be considered as an efficient way for the diastereoselective 1,4-aminohydroxylation of 1,3-dienes.