Synthesis of Pyrazolo[5,1-d][1,2,3,5]tetrazine-4(3H)-ones

A solid-phase synthesis of 5-aminopyrazole has been developed and applied to the preparation of pyrazolo[5,1-d][1,2,3,5]tetrazine-4(3H)-ones. In this strategy, a one-pot reaction from 5-aminopyrazoles to the pyrazolo[5,1-d][1,2,3,5]tetrazine-4(3H)-ones which provided the compounds in good yields was demonstrated. Using this synthetic strategy, we prepared a representative set of 16 pyrazolo[5,1-d][1,2,3,5]tetrazine-4(3H)-ones.