A tandemUgi/Mitsunobu protocol, starting from o-aminophenols, α-hydroxy acids, amines and aldehydes gives benzo[b][1,4]oxazin-3-ones of general formula 1 in two high-yielding steps, with the introduction of up to fourdiversity inputs. The mildness of the methodology allows the stereospecific synthesis of enantiomerically pure products as well as the introduction of additional functional groups. The