A convenient access to benzo-substituted phthalazines as potential precursors to DNA intercalators

2-Nitro-5-methoxybenzaldehyde is converted to amines 2 and 7 via two alternative routes. Upon diazotisation and Sandmeyer reaction, halides 4 and 9 are formed, which, through lithiation and formylation lead to the o-phthalaldehyde. Further cyclisation with hydrazine gives the 5-methoxy-substituted phthalazine.