Visible-Light-Promoted Direct Synthesis of α-Arylthioacetyloximes from Alkenes and Thiophenols

The gradual and cost-effective integration of oximes and other functional groups into organic molecules is an important and competitive research area. Here, we present a method for directly thiooximating alkenes using thiophenols and tert-butyl nitroester (^tBuONO) under visible light, without relying on photocatalysts or metal-based additives. The O-NO bond in ^tBuONO breaks upon light exposure, producing reactive tert-butoxy radical (^tBuO^•) and stable NO radicals. These species serve as both hydrogen-atom-transfer (HAT) reagents and precursors to oximes. A major advantage of this method is that it does not require photosensitizers, metal catalysts, or external heating. The reaction performs effectively with various arylalkenes and arylthiophenes, including those with significant steric hindrance and different electronic properties. Additionally, the conditions are mild, the substrate scope is broad, and the method exhibits good tolerance for various functional groups, along with operational simplicity. This allows for the synthesis of diverse α-arylthioacetyloximes in moderate to high yields. Importantly, this approach demonstrates practical value through scalability and successful late-stage modification of bioactive molecules.