This report introduces N-methylpyrrolidone hydroperoxide (NMPOOH)/base as an excellent reagent system for hydroxy-directed syn selective epoxidation of electron-deficient olefins, characterized by high diastereoselectivity, short reaction times and remarkable chemoselectivity, especially in presence of oxidatively labile nitrogen or sulfur atoms. NMPOOH also proves efficient in the oxidation of electron-deficient aromatic aldehydes, in the removal of oxazolidinone chiral auxiliary, and in the functionalization of alkenes and alkynes, showing wide application potential. Something kinda HOO-: This report introduces N-methylpyrrolidone hydroperoxide/base as an excellent system for the hydroxy-directed syn-selective epoxidation of electron-deficient olefins, characterized by high diastereoselectivity, short reaction times and remarkable chemoselectivity, especially in the presence of oxidatively labile nitrogen or sulfur atoms. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.