Preparation of 4,6-diaminopyrazolo[3,4-d] pyrimidines with variations in substitution at the 1- and 3-positions

A number of new derivatives of 4,6-diaminopyrazolo[3,4-d]pyrimidines substituted in the 1- and/or 3-positions have been obtained from reactions of guanidine carbonate with 1- and/or 3-substituted-5-amino-4-cyanopyrazoles. Use of triethanolamine as a reaction medium permitted preparation of certain derivatives which could not be obtained from the previously described fusion procedure. Some derivatives of 4-aminopyrazolo[3,4-d]pyrimidine with substitution at the 1 - and/or 3-positions were also obtained from reactions of formamide with the same 5-amino-4-cyanopyrazoles. The new compounds were screened for in vivo antimalarial activity, but were found inactive.     

The synthesis of 6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidines. II. 4-Hydroxy, 4-mercapto, 2-amino-4-hydroxy and 2,4-dihydroxy derivatives

Several new types of compounds in the 6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidine series have been prepared. Included are a 6-acyl derivative unsubstituted in the pyrimidine ring, as well as 4-hydroxy, 4-mercapto, 2-amino-4-hydroxy and 2,4-dihydroxy derivatives. These products were derived directly or indirectly from 4-cyano- or 4-carbethoxy-1-acyl-3-amino-3-pyrroline intermediates. 3-Hydroxy, 3-amino, and 3-thioformylamino-1-acyl-3-pyrroline-4-thiocarboxamides have been obtained and the 3-thioformylamino derivatives shown to undergo base-catalyzed cyclization to close a 4-mercaptopyrimidine ring.     

Compounds in the pyrrolo[3′,4′:4,5] pyrrolo[3,4-b]indole series

Compounds in the new pyrrolo[3′,4′:4,5]pyrrolo[3,4-b]indole series have been produced by an imide cyclization of appropriate derivatives of pyrrolo[3,4-b]indole.     

Thiocarbamoyl derivatives of N-acylpiperazines

1-(p-Chlorobenzoyl)piperazine failed to yield a thiocarbamoyl derivative when treated with ammonium thiocyanate; only a thiocyanate salt was formed. However, it reacted readily with benzoylisothiocyanate to form the expected 1-(N-benzoylthiocarbamoyl)-4-(p-chlorobenzoyl)piperazine. Benzoylisothiocyanate also produced an N-benzoylthiocarbamoyl derivative of 1-formylpiperazine.     

The long and short of it: the influence of N-carboxyethyl versusN-carboxymethyl pendant arms on in vitro and in vivo behavior of copper complexes of cross-bridged tetraamine macrocycles

A cross-bridged cyclam ligand bearing two N-carboxymethyl pendant arms (1) has been found to form a copper(II) complex that exhibits significantly improved biological behavior in recent research towards (64)Cu-based radiopharmaceuticals. Both the kinetic inertness and resistance to reduction of Cu-1 are believed to be relevant to its enhanced performance. To explore the influence of pendant arm length on these properties, new cross-bridged cyclam and cyclen ligands with longer N-carboxyethyl pendant arms, 2 and 4, and their respective copper(II) complexes have been synthesized. Both mono- as well as di-O-protonated forms of Cu-2 have also been isolated and structurally characterized. The spectral and structural properties of Cu-2 and Cu-4, their kinetic inertness in 5 M HCl, and electrochemical behavior have been obtained and compared to those of their N-carboxymethyl-armed homologs, Cu-1 and Cu-3. Only the cyclam-based Cu-1 and Cu-2 showed unusually high kinetic inertness towards acid decomplexation. While both of these complexes also exhibited quasi-reversible Cu(II)/Cu(I) reductions, Cu-2 is easier to reduce by a substantial margin of +400 mV, bringing it within the realm of physiological reductants. Similarly, of the cyclen-based complexes, Cu-4 is also easier to reduce than Cu-3 though both reductions are irreversible. Biodistribution studies of (64)Cu-labeled 2 and 4 were performed in Sprague Dawley rats. Despite comparable acid inertness to their shorter-armed congeners, both longer-armed ligand complexes have poorer bio-clearance properties. This inferior in vivo behavior may be a consequence of their higher reduction potentials.     

Recovery of atrazine, bromacil, chlorpyrifos, and metolachlor from water samples after concentration on solid-phase extraction disks: interlaboratory study

An interlaboratory comparison was conducted in 1997 and 1998 to examine the feasibility of using C18 solid-phase extraction disks (Empore) to simultaneously determine the herbicides atrazine, bromacil, and metolachlor and the insecticide chlorpyrifos in water samples. A common fortification source and sample processing procedure were used to minimize variation in initial concentrations and operator inconsistencies. The protocol consisted of paired laboratories in different locations coordinating their activities and shipping fortified water samples (deionized or local surface water) or Empore disks on which the pesticides had been retained and then quantitating the analytes by a variety of gas chromatographic methods. Average recoveries from all laboratories were >80% for atrazine, bromacil, and metolachlor, and >70% for chlorpyrifos. Detection of bromacil was unachievable at some locations because of chromatographic problems. Shipping samples between cooperating laboratories did not affect the recovery of atrazine, chlorpyrifos, or metolachlor in either matrix. Recoveries tended to be higher from disks shipped to cooperating laboratories compared with those from fortified water. Shipping disks eliminated many problems associated with the shipment of water samples, such as bottle breakage, higher shipping cost, and possible pesticide degradation. Recoveries of bromacil and metolachlor were lower from fortified surface water samples than from fortified deionized water samples. This collaborative research demonstrated that pesticides in water samples can be concentrated on solid-phase extraction disks at one location and quantitated under diverse analytical conditions at another location. The extraction efficiencies of the disks were comparable with or better than the recoveries obtained from the shipped water samples, and the problems associated with shipping water samples were eliminated by using the disks.     

The polarographic reduction of some dinitroaniline herbicides

Polarography of 2,6-dinitroaniline herbicides in aqueous ethanol revealed a marked pH dependence of the reduction potentials. The study included the herbicides trifluralin (I), benefin (II), isopropalin (III), dinitramine (IV), nitralin (V), and oryzalin (VI), for which E_{$\text{1}\text{2}$} values (mV vs. SCE) for the first polarographic wave, at pH 1.5, 5.1, 7.4, and 9.2, respectively, were (I) ?190, ?430, ?540, ?640; (II) ?190, ?430, ?540, ?640; (III) ?170, ?360, ?560, ?650; (IV) ?230, ?510, ?720, ?810; (V) ?160, ?330, ?540, ?650; (VI) ?160, ?370, ?540, ?680.     

2-Amino-4-aryl-6-(ω-carboxyalkyl)-5H-pyrrolo[3,4-d]pyrimidin-7-(6H)ones. Preparation via a one-pot synthesis of 1-(ω-carboxyalkyl)-4-carbethoxy-2,3-dioxopyrrolidines

1-(ω-Carboxyalkyl)-4-carboethoxy-2,3-dioxopyrrolidines were prepared by a one-pot synthesis from β-alanine or γ-aminobutyric acid, ethyl acrylate and diethyl oxalate. In a second one-pot process these products were hydrolyzed, decarboxylated and condensed with aromatic aldehydes under the influence of hydrochloric acid to yield 1-(ω-carboxyalkyl)-4-arylidene-2,3-dioxo-pyrolidines, which yielded 2-amino-4-aryl-6-(ω-carboxyalkyl)-5H-pyrrolo[3,4-d]pyrimidin-7-(6H)-ones upon treatment with guanidine. It was shown that 3,4-dihydro derivatives of certain 2-amino-4-aryl-5H-pyrrolo[3,4-d]pyrimidin-7-(6H)ones, formed initially in the guanidine reaction, readily undergo conversion to 5H-pyrrolo[3,4-d]pyrimidin-7-(6H)ones.