3-Phenyl-2-tosyl-1,2-oxaziridine is a specialized organic compound featuring a three-membered oxaziridine ring. It is a white to off-white crystalline solid with a molecular formula of C₁₄H₁₃NO₃S. This compound is a derivative of oxaziridine, a class of heterocycles known for their unique reactivity. Its primary and most significant application is as a highly selective oxidizing agent in organic synthesis. Specifically, it is known as the "Davis reagent" or "Davis oxaziridine." It is particularly valued for its ability to perform electrophilic amination reactions, transferring the tosyl-protected nitrogen atom to nucleophiles such as enolates, carbanions, and organometallic reagents to generate α-amino carbonyl compounds and other amines. It can also oxidize sulfides to sulfoxides with high chemoselectivity. Its reactivity is milder and more controllable compared to many other oxidizing agents. Due to its role as a key reagent for introducing nitrogen functionality and for selective oxidations, it is a staple in advanced synthetic methodologies, especially in the construction of complex molecules for pharmaceutical research. It is not typically used as a bulk intermediate but as a high-value, specialized reagent.