Synthesis and Cardiotonic Activity of a Series of Substituted 4-Alkyl-2(1H)-quinazolinones

Article abstract of DOI:10.1021/jm00391a026

The synthesis, cardiac fraction III cyclic nucleotide phosphodiesterase (PDE-III) inhibition, and positive inotropic activity of a series of 2(1H)-quinazolinones are reported.A general synthesis of the series involved the cyclization of 2-aminoacetophenones with potassium cyanate in acetic acid.Modifications at the 4-position of the quinazoline nucleus were best achieved by formation of the intermediate N¹-acyl-N³-phenylurea from the substituted phenyl isocyanate and appropriate carboxamide.PPA was used to ring close to the quinazoline product.Generally the SAR for the series paralleled the five-point model previously published for PDE-III inhibition.The most active analogue of the series was 5,6-dimethoxy-4-methyl-2(1H)-quinazolinone (1) (ORF 16600), which had about twice the intravenous potency of amrinone.Compound 1 is currently under development as an orally active cardiotonic.