合成路线1

Bromination of 2-amino-5-methylpyrazine (I) with Br2 in CHCl3 affords the bromopyrazine (II). Subsequent bromide displacement in (II) by means of sodium methoxide gives rise to the methoxypyrazine (III). The amino group of (III) is then protected by acylation with isobutyl chloroformate, to produce carbamate (IV). Diazotization of 3-amino-2-chloropyridine (V), followed by treatment with sulfur dioxide in the presence of CuCl furnishes sulfonyl chloride (VI). Carbamate (IV) is then acylated by means of NaH and sulfonyl chloride (VI) in DMF to furnish the N-sulfonyl carbamate (VII). Esterification of 4-carboxyphenylboronic acid (VIII) with H2SO4 in MeOH gives 4-(methoxycarbonyl)phenylboronic acid (IX). Mitsunobu coupling between boronic acid (IX) and chloropyridine (VII) furnishes adduct (X). Methyl ester (X) is converted into hydrazide (XI) by treatment with hydrazine hydrate in refluxing methanol. Then, cyclization of the acyl hydrazide (XI) with boiling triethyl orthoformate gives rise to the target oxadiazole derivative.