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Novel pyrimidoquinolone derivatives (VI),(XI),(XII), and (XIII), substituted at positions 2 and 3, are synthesized by using three synthetic routes and evaluated for their antiproliferative activities against a panel of six human cancer cell lines.

Fifteen novel pyrazolo[3,4-b]-pyrido[4,3-d]-pyrimidine-4-ones (7a–o) were designed and have been successfully synthesized via tandem aza-Wittig and annulation reactions of the corresponding iminophosphorances 5, phenylisocyanate, and substituted phenols in 60–77% isolated yields. Their structures were clearly verified by infrared (IR), 1H NMR, electron impact–mass spectrometry (EI-MS), and elemental analysis. The results of a preliminary bioassay indicated that some compounds possess inhibition activities against the root of Brassica napus (rape) and Echinochloa crusgalli (barnyard grass) at a dosage of 100 mg/L and 10 mg/L.

The carbodiimides 4, obtained from aza-Wittig reactions of iminophosphorane 3 with aromatic isocyanates, reacted with amines in the presence of a catalytic amount of RO−Na+ to give the 1,2,9-trisubstituted 1,9-dihydro-6H-purin-6-ones 6 in good yields. Compound 6 exhibited cytotoxicity against various cancer cells. For example, compounds 6b showed the best inhibition activities against KB, HepG2 and OVCAR3 with IC50 9.5, 20.4 and 10.0 μM.

Thirteen novel pyrazolo[3",4":2,3]pyrido[4,5-d]pyrimidin-4-ones 7a-m were synthesised via tandem aza-Wittig and annulation reactions of the corresponding iminophosphoranes 5, phenylisocyanate, and substituted amine in 56-86% yields. Their structures were verified by IR, 1 H NMR, El-MS spectroscopy and elemental analysis. Preliminary bioassay indicated that some compounds possess inhibition activity against Brassica napus (rape) and Echinochloa crusgalli (barnyard grass).

The carbodiimides 2, obtained from aza-Wittig reactions of iminophosphorane I with aromatic isocyanates, reacted with secondary amines or ROH to give 5-dialkylamino or 5-alkoxy 7H-1,2,3-triazolo[4,5-d]pyrimidin-7-ones 4 in the presence of a catalytic amount of EtONa in a mixed solvent (CH 2 Cl 2 -ROH). Reactions of 2 with phenols in presence of catalytic potassium carbonate in MeCN gave 5-aryloxy-7H-1,2,3-triazolo[4,5-d]pyrimidin-7-ones 4 in satisfactory yields.

The carbodiimides 2, obtained from aza-Wittig reactions of iminophosphorane 1 with aromatic isocyanates, reacted with primary amine RNH2 (R ≠ H, Me) to produce isolable guanidine intermediates 3, w...