合成路线1

6) The stereoselective cyclization of bis[(-)-menthyl] fumarate (XLVII) with 1,1-bis(methylsulfanyl)ethylene (XX) by means of diisobutylaluminum chloride in hexane gives (1S-trans)-3,3-bis(methylsulfanyl)cyclobutane-1,2-dicarboxylic acid di-(-)-menthyl ester (XLVIII), which is reduced with LiAlH4 in THF yielding (1S-trans)-3,3-bis(methylsulfanyl)cyclobutane-1,2-dimethanol (XXIV). The silylation of (XXIV) with tert-butyldimethylsilyl chloride (TBMS-Cl) and imidazole in DMF affords the bis-silylated diol (II), which is treated with AgNO3 and N-chlorosuccinimide (NCS) in acetonitrile/water to give the cyclobutanone (L). The reaction of (L) with O-methylhydroxylamine in pyridine yields the corresponding O-methyloxime (LI), which is selectively reduced with NaBH4 in THF to the cyclobutylamine (LII). The condensation of (LII) with 4-chloro-6-hydroxy-5-nitropyrimidine-2-amine (LIII) by means of triethylamine in DMF affords the substituted 5-nitro-2,4-diaminopyrimidine (LIV), which is reduced with H2 over Pd/C in formic acid yielding the corresponding triaminopyrimidine (LV). Finally, this compound, without isolation, is cyclized with formic acid at 130 C.