合成路线1

Friedel-Crafts condensation of indoline (I) with benzonitrile (II) in the presence of BCl3 and AlCl3 produced ketone (III), which was subsequently cyclized to (V) by treatment with ethyl glycinate (IV) in refluxing pyridine. The primary amino group was then introduced by conversion of (V) into oxime (VI) with isoamyl nitrite and potassium tert-butoxide, followed by catalytic hydrogenation over Ru/C to produce amine (VII) (1). The racemic amine was resolved by recrystallization as the corresponding salt with N-acetyl-L-phenylalanine to yield the desired (R)-isomer (VIII). Nitration of (VIII) with KNO3 in H2SO4 gave (IX), which was reduced to the diamino derivative (X) using stannous chloride. Finally, regioselective coupling of (X) at the aliphatic amino group with nicotinic acid (XI) by means of O-[(ethoxycarbonyl)cyanomethyleneamino]-N,N,N',N'-tetramethyluronium tetrafluoroborate (TOTU) provided the target amide.