The pyrazolo[5,1-d]-1,2,3,5-tetrazine ring is synthesized according to the general method of Ege and Gilbert by the condensation of 3-diazopyrazole-4-carboxamide (I) with 2-chloroethyl isocyanate (II) in ethyl acetate at room temperature, followed by heating the reaction mixture at 50-60 C. The product may be purified through a silica gel column using ethyl acetate as the eluent. In contrast to the preparation of mitozolomide, the entire operation, including the preparation of the starting 3-diazo derivative, can be conducted under ordinary laboratory illumination. The dry product is stable under light even after 6 months.

The pyrazolo[5,1-d]-1,2,3,5-tetrazine ring is synthesized according to the general method of Ege and Gilbert by the condensation of 3-diazopyrazole-4-carboxamide (I) with 2-chloroethyl isocyanate (II) in ethyl acetate at room temperature, followed by heating the reaction mixture at 50-60 C. The product may be purified through a silica gel column using ethyl acetate as the eluent. In contrast to the preparation of mitozolomide, the entire operation, including the preparation of the starting 3-diazo derivative, can be conducted under ordinary laboratory illumination. The dry product is stable under light even after 6 months.

The pyrazolo[5,1-d]-1,2,3,5-tetrazine ring is synthesized according to the general method of Ege and Gilbert by the condensation of 3-diazopyrazole-4-carboxamide (I) with 2-chloroethyl isocyanate (II) in ethyl acetate at room temperature, followed by heating the reaction mixture at 50-60 C. The product may be purified through a silica gel column using ethyl acetate as the eluent. In contrast to the preparation of mitozolomide, the entire operation, including the preparation of the starting 3-diazo derivative, can be conducted under ordinary laboratory illumination. The dry product is stable under light even after 6 months.

The pyrazolo[5,1-d]-1,2,3,5-tetrazine ring is synthesized according to the general method of Ege and Gilbert by the condensation of 3-diazopyrazole-4-carboxamide (I) with 2-chloroethyl isocyanate (II) in ethyl acetate at room temperature, followed by heating the reaction mixture at 50-60 C. The product may be purified through a silica gel column using ethyl acetate as the eluent. In contrast to the preparation of mitozolomide, the entire operation, including the preparation of the starting 3-diazo derivative, can be conducted under ordinary laboratory illumination. The dry product is stable under light even after 6 months.