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An improved method for the synthesis of some new dihydropyrimidines from aromatic aldehydes, 1,3-dicarbonyl compounds, and thiourea with significant enhancement in reaction rates, short reaction time (4–6 h), good to excellent yields (70–93%), and ambient temperature using molecular iodine as catalyst is described. The biological evaluation revealed that the newly synthesized compounds and exhibited good antimicrobial activity and moderate antimycobacterial activity against Mycobacterium tuberculosis H37RV.

Heterosubstituted chalcones and oxopyrimidines were synthesized by the reaction of 2-(4-Chlorophenyl)imidazo[1,2-a]pyridine-3-carbaldehyde 1 and different aryl acetophenone in the presence of catalytic amount of 40% alkali to give (2E)-3-(2-(4-chlorophenyl)imidazo[1,2-a]pyridin-3-yl)-1-arylprop-2-en-1-ones 2a–l. Compounds 2a–l on reaction with urea in the presence of basic catalyst such as KOH to give 6-(2-(4-chlorophenyl)imidazo[1,2-a]pyridin-3-yl)-4-aryl pyrimidin-2(1H)-ones 3a–l. Their IR, 1H-NMR, MASS spectral data, and elemental analysis were in accord with assigned structure. All the newly synthesized compounds were screened for their antimicrobial activity. J. Heterocyclic Chem., (2012).

Bisbenzoxazines of bisphenol-C (BCO) and phenolphthalein (PHO) were synthesized by condensing 0.05 mol bisphenol-C/phenolphthalein, 0.2 mol formaldehyde, and 0.1 mol aniline. Both BCO and PHO were thermally polymerized via ring-opening polymerization. The resultant cross-linked polymers (PBCO and PPHO) were characterized by solubility, Infrared (IR), Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). The bisoxazines and their polymers followed two-step degradation. Both BCO and PHO undergo selective ring-opening polymerization over the temperature range 100–150°C and are thermally stable up to about 250°C. The % residue at 550°C is substantially higher for PHO samples (56–67%) than BCO samples (20–25%), indicating the highly thermally stable nature of PHO. A ring transformation reaction is also supported by DSC. New thermosetting materials may be useful for specific applications to be exploited.

The formation of dihydropyrimidines (IV) and (VII) from dicarbonyl compounds, aromatic aldehydes, and thiourea derivatives occurs with significant enhancement with regard to reaction rates, reaction time, and yield by using molecular iodine as the catalyst.

Heterosubstituted chalcones and oxopyrimidines were synthesized by the reaction of 2-(4-Chlorophenyl)imidazo[1,2-a]pyridine-3-carbaldehyde 1 and different aryl acetophenone in the presence of catalytic amount of 40% alkali to give (2E)-3-(2-(4-chlorophenyl)imidazo[1,2-a]pyridin-3-yl)-1-arylprop-2-en-1-ones 2a–l. Compounds 2a–l on reaction with urea in the presence of basic catalyst such as KOH to give 6-(2-(4-chlorophenyl)imidazo[1,2-a]pyridin-3-yl)-4-aryl pyrimidin-2(1H)-ones 3a–l. Their IR, 1H-NMR, MASS spectral data, and elemental analysis were in accord with assigned structure. All the newly synthesized compounds were screened for their antimicrobial activity. J. Heterocyclic Chem., (2012).

All newly synthesized compounds are tested for their antibacterial and antitubercular activity.