1,1-Dimethylhydrazine → 2-(Dimethylamino)isoindoline-1,3-dione

Participants

Reaction Steps

Phthalazine derivatives of formula IA were prepared as described in FIG. 8 and as further detailed in Example 4. The commercially available phthalic anhydride was reacted with N,N-dimethyl hydrazine to give 2-(dimethylamino)isoindoline-1,3-dione 16 in good yield [Hanefeld W et al. J Heterocyclic Chem. 1996;33:1443]. Then, 16 was reacted with phenylmagnesium bromide, to lead to the intermediate 17 in good yield [Deniau E et al. Tetrahedron: Asym. 2003;14:2253], which in turn was quantitatively converted by reaction with hydrazine to 4-phenylphthalazin-1(2H)-one 18 [Saito Y et al. Synthesis 2001;2:221]. Finally, the N-amidation product 19 (Compound I) was the major product obtained in good yield whatever the experimental conditions. Two different carbamoyl chlorides were used (R1=CH3—compound 19a; and i-Pr—compound 19b) for the preparation of phthalazine derivatives. (FIG. 8).

Provenance & Evidence