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Part-IIImpact of Microwave…Nie et al., 51 reported microwave-assisted reaction of 2’-hydroxychalcones with amidinesor guanidines to synthesize 2,4,6-trisubstitutedpyrimidines 55 (100 compounds).R 2R 1OOH+ArHNR 2 NH 2MWI, 190 o C, 30 minR 1NOH55NArR 1 = H, F, Cl, BrR 2 = Ph, 4-CH 3 Ph, 4-ClPh, cyclopropyl, NH 2An efficient and rapid microwave-assisted solution-phase method for the synthesis of 2-amino-4-arylpyrimidine 5-carboxylic acid derivatives has been developed. The five-steplinear protocol involves an initial Biginelli multicomponent reaction leading todihydropyrimidine-2-thiones 56 which are subsequently S-alkylated with methyl iodide.The resulting 2-methylthiodihydropyrimidines 57 are sequentially oxidized first withmanganese dioxide and then with oxone to provide 2-methylsulfonyl-pyrimidines 58which serve as excellent precursors for the generation of a variety of 2-substitutedpyrimidines 59 via displacement of the reactive sulfonyl group with nitrogen, oxygen,sulfur, and carbon nucleophiles. The use of high-temperature sealed-vessel microwaveirradiation allows the preparation of the desired target structures in high yields andcomparatively short reaction times. 52OPhOPhOPhEtOO+OH 2 NHNH 2TMSClMeCN, DMFEtONHMWI, 120 o C,10 min NHS56MeI, MeCN,MWI, 100 o C, 5 minSNaOH (1M)EtONHNSMeMnO 2 ,MWI, 100 o C20 minOPhOPhOPhEtON59N nucleophile, baseEtOMWI, 70-230 o C, 10 minNuNu= pyrrolidine, piperidine,ethanolamine, amonia, phenol etcN58NOSOxone, H 2 O, MeOHEtOMWI, 100 o C, 20 minON57NSMe299