Solid-phase library synthesis of triazolopyridazines via [4+2] cycloadditions

An Efficient and Convenient Approach for the Synthesis of Novel Pyrazolo[1,2-a]triazole-triones and Evaluation of their Antimicrobial Activities

A new protocol for the efficient synthesis of novel pyrazolo[1,2-a]triazole-1,3,5-triones has been developed. The synthesis was achieved by reaction of aromatic aldehydes, Meldrum’s acid, and 4-phenylurazole in the presence of a catalytic amount of glacial AcOH at 80°C. The structural assignment has been unambiguously confirmed by X-ray analysis. The present finding provides an environmentally benign, efficient, and promising synthetic strategy for the synthesis of libraries with diversity. These compounds were tested in vitro for their antibacterial activity against four strains, namely Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa and antifungal activity against two fungal strains, namely Aspergillus niger and Aspergillus flavus.

Stereoselective Aza Diels−Alder Reaction on Solid Phase: A Facile Synthesis of Hexahydrocinnoline Derivatives

As part of our continuing studies of polymer-supported pericyclic reactions for preparing biologically interesting heterocyclic compounds, we have introduced a traceless solid-phase synthesis of hexahydrocinnolines. We developed a method in which mild reaction conditions can be used for the hetero-Diels-Alder reactions on a polymeric support. The dienoic 3-vinyl-2-cyclohexenol attached to a Wang resin through an ether linkage undergoes [4 + 2] cycloaddition reaction with several azadienophiles. The highly stereoselective Diels-Alder reaction showed preferential formation of a single cycloadduct resulting from an anti attack of the dienophile on the polymer-bound diene. Trifluoroacetic acid-mediated cleavage of the polymer-bound cycloadducts yields fused nonaromatic hexahydrocinnolines in moderate yields in three steps.

Discovery of a Potent and Novel Motilin Agonist

A novel series of dihydro- and tetrahydrotriazolopyridazine-1,3-dione-based amino acid derivatives were identified as very potent motilin receptor agonists. Incorporating one additional phenylethyl glycinamide subunit to 1 (EC(50) = 660 nM) was found to improve in vitro potency approximately 3000-fold, resulting in compound 10 (EC(50) = 0.22 nM). The more potent enantiomer 11A has an EC(50) of 0.047 nM in the motilin receptor functional assay and a K(i) of 0.7 nM in the binding assay. In addition, compound 11A was shown to have a significantly reduced tendency to cause receptor desensitization as compared with the motilin receptor agonist ABT-229.

Vibrational frequencies and structural determinations of urazole

The vibrational frequencies and corresponding normal mode assignments of urazole are examined theoretically using the Gaussian98 set of quantum chemistry codes. All normal modes were successfully assigned to one of eight types of motion (N--H stretch, C=O stretch, C--N stretch, N--N stretch, N--H bend, C=O bend, N--C--N bend, ring torsion) utilizing the C2 symmetry of the molecule. The molecular orbitals of urazole are examined. The simultaneous double inversion of the amine groups in urazole is also examined.