Pauline Cohen-Fernandes

Nucleophilic behaviour of DBU and DBN in reactions with 4-halo-3,5-dimethyl-1-nitro-1H-pyrazoles

Abstract Addition of 3 equivalents of DBU or DBN to a solution of 4-halo-3,5-dimethyl-1-nitro-1H-pyrazole ( 5a-c ) in acetonitrile affords the unexpected products 6a-c and 7a-c in fair to good yields. A reaction mechanism is proposed involving an elimination of HNO 2 giving a diazafulvene intermediate 8 followed by the addition of a second molecule of DBU or DBN to 8 .

Rearrangement of N-nitro-1,2,4-triazoles into 3-nitro-1,2,4-triazoles

Syntheses of the N-nitro-1,2,4-triazoles (1) and (2) and their thermal isomerization into the 3-nitroderivatives (3) and (4) is described; this thermal rearrangement of N-nitro-azoles to their corresponding C-nitro-compounds is suggested to be an example of a [1,5] sigmatropic shift of the NO2 group.