合成路线1

The intermediates indolyloxy pyrrolotriazines (I) and (VII) can be prepared as follows. Cyclization of 2-oxobutyric acid (IX) with formamidine hydrochloride and hydrazine hydrate in the presence of AcOH in refluxing EtOH yields 6-ethyl-1,2,4-triazin-5-one (X). Subsequent condensation of triazinone (X) with 3-bromopyruvic acid (XI) in aqueous solution at 90 °C gives the pyrrolotriazine carboxylic acid (XII), which is esterified with refluxing EtOH/HCl to furnish ester (XIII) . Chlorination of hydroxypyrrolotriazine (XIII) with POCl3, optionally in the presence of DIEA, in refluxing toluene affords the 4-chloro derivative (XIV) , which is condensed with 4-fluoro-5-hydroxy-2-methylindole (XV) by means of K2CO3 in DMF to yield the indolyloxypyrrolotriazine adduct (VII) . Alternatively, displacement of chlorine in compound (XIV) with ethanolic NaOEt yields the 4-ethoxy derivative (XVI). Then, addition of methylmagnesium bromide to the ester group of (XVI) in THF leads to the tertiary alcohol (XVII), which undergoes oxidative cleavage to 4-ethoxy-6-hydroxy-5-methylpyrrolo[2,1-f]-1,2,4-triazine (XVIII) by treatment with H2O2 and BF3·Et2O in CH2Cl2. After protection of the hydroxyl group of (XVIII) with benzyl bromide and K2CO3 in DMF, selective cleavage of the O-ethyl group in the resulting diether (XIXa) by means of HCl in hot ethanol provides 6-benzyloxy-4-hydroxy-5-methylpyrrolo[2,1-f]-1,2,4-triazine (XXI) . Similarly, the 4-phenoxy analogue (XX) is protected as the corresponding benzyl ether (XIXb), which undergoes O-phenyl group cleavage to (XXI) upon heating with HCl . Reaction of alcohol (XXI) with POCl3 in refluxing toluene provides the 4-chloro derivative (XXII), which is then coupled with 4-fluoro-5-hydroxy-2-methylindole (XV) by means of NaH in DMF to provide intermediate (I) .