合成路线1

Pyridine (III) was prepared by condensation of malononitrile (I) with triethyl orthoformate (II) in refluxing pyridine, followed by treatment with concentrated HCl. Dechlorination of (III) was effected by hydrogenolysis in the presence of Pd on BaCO3. The dechlorinated pyridine dinitrile (IV) was cyclized with guanidine (V), yielding the pyridopyrimidine (VI). Reduction of the nitrile function of (VI) to aldehyde (VII) was carried out using formic acid and Raney-Ni. This was further reduced to alcohol (VIII) with NaBH4. Bromination of the alcohol (VIII) by means of HBr resulted in bromide (IX). Nucleophilic displacement of the bromide group of (IX) with the sodium salt of 1-naphthalenethiol (X) afforded the target sulfide.