Aminocinnolines preparation

In particular, 4-aminocinnolines prepared in this manner have often synthesized to compete for nucleotide co-factors in kinases and phosphodiesterases. " Thus 4-cinnolones have been used as key intermediates in the synthesis of inhibitors of these families of enzymes. 

Preparations of pyridazino[3,4- [l,3]oxazines by ozonolysis of pyrrolo[2,3-b]pyridazine-3-carboxylates and from the reaction of A -(4-ethoxycarbonylpyridazin-3-yl)phosphinimines with acyl halides were described in CHEC-II(1996) <1996CHEC-11(7)737>. A simpler form of the latter approach has now been reported <1994CC2451>, wherein the 1-A -oxide of 3-aminocinnoline-4-carboxylic acid undergoes cyclization with acetic anhydride (Equation 126). The isomeric pyridazino[4,3-, [l,3]oxazines have been prepared in a similar manner (Equation 127) <1997PHA838>. 

Some new synthetic approaches have been published in the 1990s. By refluxing 4-aminocinnoline-3-carboxylic acid (56) with aryl isothiocyanates substituted 2-thiol-3-(JV-aryl)pyrimido[5,4-c]cin-nolin-4(3//)-ones (57) are prepared (Equation (4)) <92AHC(55)129>. 

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