Highly selective scalable electrosynthesis of 4-hydroxybenzo[e]-1,2,4-thiadiazine-1,1-dioxides

4H-4-Hydroxybenzo[e]-1,2,4-thiadiazine-1,1-dioxides are based on a widely found structural motif for pharmaceutical applications, having an additional unique exocyclic N–O bond that is not accessible by conventional synthetic routes. Electrochemistry offers a sustainable tool for the direct synthesis of these heterocyclic structures containing this N-hydroxy modification. Here, we report a highly selective synthesis of 4H-4-hydroxybenzo[e]-1,2,4-thiadiazine-1,1-dioxides by direct reduction of widely available nitro arenes in almost quantitative yields. The electro-synthetic protocol is applied to more than 40 diverse examples, highlighting the versatility of this method. Furthermore, the technical relevance is demonstrated by two multi-gram-scale syntheses.