The cyclization of 1-(2-fluorobenzyl)pyrazolo[3,4-b]pyridine-3-carboxamidine (I) (see scheme no. 28591301a, intermediate (IX)) with phenylazomalononitrile (II) by means of NaOMe in hot DMF gives the pyrimidine (III), which is reduced with H2 over RaNi in hot DMF to yield the triaminopyrimidine (IV). The reductocondensation of (IV) with 2-(tert-butyldimethylsilyloxy)acetaldehyde (V) by means of NaBH3CN in methanol/AcOH affords the adduct (VI), which is desilylated by means of TBAF in THF to provide the 2-hydroxyethylamino derivative (VII). Finally, this compound is cyclized with aqueous glyoxal (VIII) to furnish the target tricyclic compound.
The cyclization of 1-(2-fluorobenzyl)pyrazolo[3,4-b]pyridine-3-carboxamidine (I) (see scheme no. 28591301a, intermediate (IX)) with ethyl 2-(ethoxymethylene)cyanacetate (II) in refluxing toluene gives the pyrimidine-5-carboxylate derivative (III), which is cyclized to the target 1-hydroxycyclopropyl derivation by reaction with CH2I2 and SmI2 in hot THF.