Effect of aromatic substituents on the outcome of base-induced rearrangements of 3-acetyl-2,4-dimethyl-3,4-dihydro-2H-1,2,3-benzothiadiazine 1,1-dioxides

Dearomative spiroannulation of indoles enabled by the diaza-[1,2]-Wittig rearrangement

“…Tetrasubstituted hydrazines undergo the cleavage of N–N bonds, and the terminal amino unit [1,2] shifts via possible imine and amine intermediates. 48–52 Due to the relatively weak N–N bond, a reaction involving the diaza-[1,2]-Wittig rearrangement can be conducted under mild conditions. 53–56 For instance, Liu/Zhou reported a selective N–N bond activation/[6 + 1] annulation cascade between pyrazolidinones and diazopyrazolones without a base for the synthesis of spiropyrazolone skeletons.…”