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Paper | Special issue | Vol 67, No. 1, 2006, pp.161-173
Published online, 13th May, 2005
DOI: 10.3987/COM-05-S(T)9
A Diversity Oriented Synthesis of 2,10-Dioxo-10H-1,2,3,4,4a,5-hexahydropyridazino[3,2-b]quinazolines

Elisabeth Schuler, Nacho Juanico, Jordi Teixidó, Enrique L. Michelotti, and José I. Borrell*

*Grup d’Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona, Spain

Abstract

A parallel method for the synthesis of the title compounds is described. Thus, methyl anthranilates (5) are transformed into 2-aminobenzohydrazides (3) which were treated with 4-oxo acids (4) to afford in high yields and acceptable purity of piridazino[3,2-b]quinazolines (1). Compounds (1) present four diversity centers (R1, R2, R3, and R4). The range of chemically acceptable substituents at each center has been evaluated. The isolation of a possible intermediate in the formation of 1, which presents an aminol structure (10), has allowed proposing a complete mechanistic rationalization for the formation of structures (1).