Pyrazolo[3,4-c]pyridazines as novel and selective inhibitors of cyclin-dependent kinases.

Pyrazolopyridazine 1a was identified in a high-throughput screening carried out by BASF Bioresearch Corp. (Worcester, MA) as a potent inhibitor of CDK1/cyclin B and shown to have selectivity for the CDK family. Analogues of the lead compound have been synthesized and their antitumor activities have been tested. A molecular model of the complex between the lead compound and the CDK2 ATP binding site has been built using a combination of conformational search and automated docking techniques. The stability of the resulting complex has been assessed by molecular dynamics simulations and the experimental results obtained for the synthesized analogues have been rationalized on the basis of the proposed binding mode for compound 1a. As a result of the SAR study, monofuryl 1o has been synthesized and is one of the most active compounds against CDK1 of this series.

A novel series of complexones with bis- or biazole structure as mixed ligands of paramagnetic contrast agents for MRI.

We describe the syntheses, physicochemical properties and biological evaluation of a novel series of complexones containing bis- or biazoles moieties and two iminodiacetic acid units as novel ligands for paramagnetic lanthanides. The complexones were prepared by reaction of the corresponding 1,1'-bishaloethylbi- or bispyrazoles with methyl iminodiacetate and subsequent NaOH hydrolysis. 1,1'-Bisbromoethyl precursors were obtained by direct alkylation with an excess of 1,2-dibromoethane, or by heating the corresponding alcohol in HCl. Sigmoidal binding isotherms and MO calculations supported as most stable structures in solution, those containing two Gd(III) atoms bound per molecule of complexone with half saturation values S(0.5) (M(-1), 22 degrees C, pH 7.2) in the range 6.5 10(-6)