Search

The synthesis of ethyl or methyl 4-substituted or unsubstituted 2-(dimethylamino)-5-pyrimidinecarboxylates 10-20, which is mainly carried out by reaction of ethyl or methyl 2-[(dimethylamino)methylene]-3-oxoalkanoates with 1,1-dimethylguanidine, is described. The above esters were hydrolyzed to the relative carboxylic acids 21-30, which were decarboxylated to the corresponding 2,4-disubstituted pyrimidines 31-40. All the new synthesized pyrimidines were evaluated in spontaneously beating and electrically driven atria from reserpine-treated guinea pigs. Their effects were compared to those induced by milrinone in both atria preparations. Compound 28 (4-benzyl-2-(dimethylamino)-5-pyrimidinecarboxylic acid) was the most effective positive inotropic agent, while the corresponding methyl ester 17 reduced both the contractile force and the frequency of guinea pig atria. An antagonism toward the negative influence exerted by endogenous adenosine on the heart seems to be involved in the contractile activity of compound 28. By contrast, compound 17 might be partial agonist at the purinergic inhibitory (A1) receptor. X-ray analysis carried out on 17 and 28 and molecular modeling investigations extended also to related derivatives allowed a possible rationalization between structure and inotropic activity for this series of compounds.

The compound bis[η-(1,3,3,5,5-pentamethylcyclohexyl)-cyclopentadienyl] zirconium dichloride has been prepared and the crystal structure determined. The compound together with the cocatalyst methylaluminoxane will catalyse the polymerisation of the ethene and propene.

The Schiff-base condensation of 2,6-diacetylpyridine and 1,2-diaminobenzene in the presence of uranyl salts produced complexes of the general formula (UP{sub 2}(C{sub 30}H{sub 26}N{sub 6}))X{sub 2}, with X = ClO{sub 4}{sup {minus}}, NO{sub 3}{sup {minus}}, and CH{sub 3}COO{sup {minus}}. A related complex, (Pr(NO{sub 3}){sub 2}(CH{sub 3}OH)(C{sub 30}H{sub 26}N{sub 6}))(ClO{sub 4}){center dot}0.5CH{sub 3}OH{center dot}0.5H{sub 2}O, was obtained from a similar metal-templated reaction followed by partial anion metathesis. The Pr(III) complex crystallized in the monoclinic space group P2{sub 1}/c with Z = 4 in a cell having a = 20.198 (3) {angstrom}, b = 14.208 (2) {angstrom}, c = 12.727 (2) {angstrom}, and {beta} = 104.25 (4){degree}. In this complex the Pr(III) ion was 11-coordinated, being linked to the six nitrogen atoms of an 18-membered macrocyclic ligand, to two bidentate nitrates situated on opposite sides of the macrocycle, and to one molecule of methanol. A noncoordinated ClO{sub 4}{sup {minus}} ion balanced the cationic charge of the complex cation; clathrated water and methanol were also present. The macrocyclic cations existing in these uranyl and praseodynium(III) complexes retained their identity in solution and were moderately inert to metal release in the present of acids or bases. 15 refs., 3 figs., 5 tabs.