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Su-Naval Rearrangement
The Su-Naval Rearrangement reaction in organic chemistry was discovered by Prof.Tsann-Long Su and Dr. Naval P. Kapuriya in the year 2008.[1] It involves an oxidative rearrangement of Phenyl ring of Anilines to produce (E)-Benzaldoximes by treatment with Paraformaldehyde and H2O2. This rearrangement is one pot procedure where reaction of anilines with paraformaldehyde in refluxing 1,4-dioxane produce 1,3,5-triazinane intermediate which further in-situ treated with 30% H2O2 to yield benzaldoxime through rearrangement of phenyl ring from Nitrogen to Carbon atom. This reaction was the first report where Benzaldoximes were directly produced from anilines without involving benzaldehyde and hydroxylamine.[2-5]

Su-Naval Rearrangement Reaction Mechanism: The following scheme shows the reaction mechanism of Su-Naval Rearrangement. Initially reaction of paraformaldehyde reacts anilines in refluxing 1,4-dioxane to generate 1,3,5-triazinane (2).[6-7] Under heating condition, 1,3,5-trizinanes are unstable and decompose to produce reactive N-phenylmethanimine (3). The in-situ treatment of 30% H2O2 oxidizes the intermediate (3) to oxazirane (4) in a similar manner as of oxidation of alkenes to epoxides. Further oxazirane ring opening reaction in the presence of H+ generate electron deficient Carbon (5) which promote shifting of phenyl ring from Nitrogen atom to Carbon via neighboring group participation (6) leading to furnish (E)-Benzaldoximes (8) as major product.

Representative Examples:

1.	Benzaldoxime in 54% yield from Paraformaldehyde in refluxing 1,4 dioxane followed by 30% H2O2; Refluxing 2-3 h.

2.	4-Methoxy benzaldoxime in 55% yield fromParaformaldehyde in refluxing 1,4 dioxane followed by 30% H2O2; Refluxing 2.5 h.

3.



61 % with Paraformaldehyde in refluxing 1,4 dioxane followed by 30% H2O2; Refluxing 2.5 h,

References