Synthesis of 2-Hydroxy-1,4-oxazin-3-ones through Ring Transformation of 3-Hydroxy-4-(1,2-dihydroxyethyl)--lactams and a Study of Their Reactivity

K. Mollet, H. Goossens, N. Piens, S. Catak, M. Waroquier, V. Van Speybroeck, M. D'Hooghe, N. De Kimpe
Chemistry - A European Journal
19 (10), 3383-3396


The reactivity of 3-hydroxy-4-(1,2-dihydroxyethyl)-β-lactams with regard to the oxidant sodium periodate was evaluated, unexpectedly resulting in the exclusive formation of new 2-hydroxy-1,4-oxazin-3-ones through a C3C4 bond cleavage of the intermediate 4-formyl-3-hydroxy-β-lactams followed by a ring expansion. This peculiar transformation stands in sharp contrast with the known NaIO4-mediated oxidation of 3-alkoxy- and 3-phenoxy-4-(1,2-dihydroxyethyl)-β-lactams, which exclusively leads to the corresponding 4-formyl-β-lactams without a subsequent ring enlargement. In addition, this new class of functionalized oxazin-3-ones was further evaluated for its potential use as building blocks in the synthesis of a variety of differently substituted oxazin-3-ones, morpholin-3-ones and pyrazinones. Furthermore, additional insights into the mechanism and the factors governing this new ring-expansion reaction were provided by means of density functional theory calculations.