A diversity oriented synthesis of 10H-pyridazino[6,1-b]quinazolin-10-ones and their ring opening derivatives

A parallel method for the synthesis of the title compounds is described. Thus, anthranilic acids (2) were treated with 3-chloropyridazines (3) in a 2:1 propanol:water mixture using HCI as acid catalyst to yield 10H-pyridazino[6,1-b] quinazolin-10-ones (1). Compounds (1) present three diversity centers (R ₁, R₂ and R₃). The range of chemically acceptable substituents at each center has been evaluated. The ring opening of compounds 1 afforded benzoic acids 5 which in turn are easily ciclyzed to 1H-pyridazino[6,1-D]quinazoline-2,10-diones (4) with TFA. The N- and O-alkylation of 4{1,1} has been also studied.