DNA-Directed Alkylating Agents. 7. Synthesis, DNA Interaction, and Antitumor Activity of Bis(hydroxymethyl)- and Bis(carbamate)-Substituted Pyrrolizines and Imidazoles

Abstract

A series of bis(hydroxymethyl)-substituted imidazoles, thioimidazoles, and pyrrolizines and related bis(carbamates), linked to either 9-anilinoacridine (intercalating) or 4-(4-quinolinylamino)benzamide (minor groove binding) carriers, were synthesized and evaluated for sequence-specific DNA alkylation and cytotoxicity. The imidazole and thioimidazole analogues were prepared by initial synthesis of [(4-aminophenyl)alkyl]imidazole-, thioimidazole-, or pyrrolizine dicarboxylates, coupling of these with the desired carrier, and reduction to give the required bis(hydroxymethyl) alkylating moiety. The pyrrolizines were the most reactive alkylators, followed by the thioimidazoles, while the imidazoles were unreactive. The pyrrolizines and some of the thioimidazoles cross-linked DNA, as measured by agarose gel electrophoresis. Strand cleavage assays showed that none of the compounds reacted at purine N7 or N3 sites in the gpt region of the plasmid gpt2Eco, but the polymerase stop assay showed patterns of G-alkylation in C-rich regions. The corresponding thioimidazole bis(carbamates) were more selective than the bis(hydroxymethyl) pyrrolizines, with high-intensity bands at 5'-NCCN, 5'-NGCN and 5'-NCGN sequences in the PCR stopping assay ( indicates block sites). The data suggest that these targeted compounds, like the known thioimidazole bis(carbamate) carmethizole, alkylate exclusively at guanine residues via the 2-amino group, with little or no alkylation at N3 and N7 guanine or adenine sites. The cytotoxicities of the compounds correlated broadly with their reactivities, with the bis(hydroxymethyl)imidazoles being the least cytotoxic (IC50s >1 microM; P388 leukemia) and with the intercalator-linked analogues being more cytotoxic than the corresponding minor-groove-targeted ones. This was true also for the more reactive thioimidazole bis(carbamates) (IC50s 0.8 and 11 microM, respectively), but both were more active than the analogous "untargeted" carmethizole (IC50 20 microM). The bis(hydroxymethyl)pyrrolizine analogues were the most cytotoxic, with IC50s as low as 0.03 microM.

Iodine‐Catalyzed C−H Functionalization of Cyclopentenedione with Benzamidine: A Double Dehydrogenative Oxidative Cyclization to Access Fused Imidazoles

“…Similarly, the reaction of 4-chlorobenzamidine hydrochloride with electron-donating groups such as methyl, ethyl, and isopropyl group on the phenyl moiety of 2-benzyl-2-methylcyclopent-4-ene-1,3-dione furnished the corresponding fused imidazole derivatives 3 cb, 3 cc, and 3 cd in 80, 68, and 85% yields, respectively. The reaction of 4-chlorobenzamidine hydrochloride with heliotropin derived substrate, 2-(benzo[d] [1,3]dioxol-5-ylmethyl)-2-methylcyclopent-4-ene-1,3-dione, afforded the corresponding fused imidazole derivative 3 ce in 66% yield. The reaction of 4-chlorobenzamidine hydrochloride with 2-benzyl-2methylcyclopent-4-ene-1,3-dione derivative with an electron-withdrawing moiety such as fluorine on the phenyl ring afforded the corresponding fused imidazole 3 cf in 90% yield.…”

Iodine‐Catalyzed C−H Functionalization of Cyclopentenedione with Benzamidine: A Double Dehydrogenative Oxidative Cyclization to Access Fused Imidazoles

“…Similarly, the reaction of 4-chlorobenzamidine hydrochloride with electron-donating groups such as methyl, ethyl, and isopropyl group on the phenyl moiety of 2-benzyl-2-methylcyclopent-4-ene-1,3-dione furnished the corresponding fused imidazole derivatives 3 cb, 3 cc, and 3 cd in 80, 68, and 85% yields, respectively. The reaction of 4-chlorobenzamidine hydrochloride with heliotropin derived substrate, 2-(benzo[d] [1,3]dioxol-5-ylmethyl)-2-methylcyclopent-4-ene-1,3-dione, afforded the corresponding fused imidazole derivative 3 ce in 66% yield. The reaction of 4-chlorobenzamidine hydrochloride with 2-benzyl-2methylcyclopent-4-ene-1,3-dione derivative with an electron-withdrawing moiety such as fluorine on the phenyl ring afforded the corresponding fused imidazole 3 cf in 90% yield.…”

Cycloaddition Reactions of Alkyl Cyclopropenecarboxylates Generated in situ with Nitrones: Construction of Substituted Pyrroles and 1,2‐Oxazinanes

“…The pyrrolizine skeleton widely exists in pharmaceuticals such as antitumor, [14] antileukemic, [15] analgesic, and anti-inflammatory agents, [16] and therefore this reaction provides a convenient protocol for the preparation of important pyrrolizine derivatives with versatile functional groups. The main product isolated from the reaction mixture was carefully characterized by spectroscopic means and finally identified as the 2,3-dihydro-1H-pyrrolizine derivative 5ia rather than the desired [3+2] cycloaddition product 3ia (Scheme 2).…”

Modular Synthesis of Tetrasubstituted Imidazoles and Trisubstituted Oxazoles by Aldimine Cross‐Coupling

“…Whereas the unsubstituted parent compound serves as a nucleophilic catalyst or corrosion inhibitor, its derivatives exhibit a wide range of biological activities. For example, anti‐inflammatory,6 antibacterial,7 antimycotic,8 as well as cytostatic9, 10 imidazoles have been described. Imidazolium salts can be used as ionic liquids or as precursors of versatile N‐heterocyclic carbenes 11.…”

Iodine‐Catalyzed C−H Functionalization of Cyclopentenedione with Benzamidine: A Double Dehydrogenative Oxidative Cyclization to Access Fused Imidazoles

“…Similarly, the reaction of 4-chlorobenzamidine hydrochloride with electron-donating groups such as methyl, ethyl, and isopropyl group on the phenyl moiety of 2-benzyl-2-methylcyclopent-4-ene-1,3-dione furnished the corresponding fused imidazole derivatives 3 cb, 3 cc, and 3 cd in 80, 68, and 85% yields, respectively. The reaction of 4-chlorobenzamidine hydrochloride with heliotropin derived substrate, 2-(benzo[d] [1,3]dioxol-5-ylmethyl)-2-methylcyclopent-4-ene-1,3-dione, afforded the corresponding fused imidazole derivative 3 ce in 66% yield. The reaction of 4-chlorobenzamidine hydrochloride with 2-benzyl-2methylcyclopent-4-ene-1,3-dione derivative with an electron-withdrawing moiety such as fluorine on the phenyl ring afforded the corresponding fused imidazole 3 cf in 90% yield.…”

Cycloaddition Reactions of Alkyl Cyclopropenecarboxylates Generated in situ with Nitrones: Construction of Substituted Pyrroles and 1,2‐Oxazinanes

“…The pyrrolizine skeleton widely exists in pharmaceuticals such as antitumor, [14] antileukemic, [15] analgesic, and anti-inflammatory agents, [16] and therefore this reaction provides a convenient protocol for the preparation of important pyrrolizine derivatives with versatile functional groups. The main product isolated from the reaction mixture was carefully characterized by spectroscopic means and finally identified as the 2,3-dihydro-1H-pyrrolizine derivative 5ia rather than the desired [3+2] cycloaddition product 3ia (Scheme 2).…”

Modular Synthesis of Tetrasubstituted Imidazoles and Trisubstituted Oxazoles by Aldimine Cross‐Coupling

“…Whereas the unsubstituted parent compound serves as a nucleophilic catalyst or corrosion inhibitor, its derivatives exhibit a wide range of biological activities. For example, anti‐inflammatory,6 antibacterial,7 antimycotic,8 as well as cytostatic9, 10 imidazoles have been described. Imidazolium salts can be used as ionic liquids or as precursors of versatile N‐heterocyclic carbenes 11.…”

Iodine‐Catalyzed C−H Functionalization of Cyclopentenedione with Benzamidine: A Double Dehydrogenative Oxidative Cyclization to Access Fused Imidazoles

“…Similarly, the reaction of 4-chlorobenzamidine hydrochloride with electron-donating groups such as methyl, ethyl, and isopropyl group on the phenyl moiety of 2-benzyl-2-methylcyclopent-4-ene-1,3-dione furnished the corresponding fused imidazole derivatives 3 cb, 3 cc, and 3 cd in 80, 68, and 85% yields, respectively. The reaction of 4-chlorobenzamidine hydrochloride with heliotropin derived substrate, 2-(benzo[d] [1,3]dioxol-5-ylmethyl)-2-methylcyclopent-4-ene-1,3-dione, afforded the corresponding fused imidazole derivative 3 ce in 66% yield. The reaction of 4-chlorobenzamidine hydrochloride with 2-benzyl-2methylcyclopent-4-ene-1,3-dione derivative with an electron-withdrawing moiety such as fluorine on the phenyl ring afforded the corresponding fused imidazole 3 cf in 90% yield.…”

Cycloaddition Reactions of Alkyl Cyclopropenecarboxylates Generated in situ with Nitrones: Construction of Substituted Pyrroles and 1,2‐Oxazinanes

“…The pyrrolizine skeleton widely exists in pharmaceuticals such as antitumor, [14] antileukemic, [15] analgesic, and anti-inflammatory agents, [16] and therefore this reaction provides a convenient protocol for the preparation of important pyrrolizine derivatives with versatile functional groups. The main product isolated from the reaction mixture was carefully characterized by spectroscopic means and finally identified as the 2,3-dihydro-1H-pyrrolizine derivative 5ia rather than the desired [3+2] cycloaddition product 3ia (Scheme 2).…”

Modular Synthesis of Tetrasubstituted Imidazoles and Trisubstituted Oxazoles by Aldimine Cross‐Coupling

“…Whereas the unsubstituted parent compound serves as a nucleophilic catalyst or corrosion inhibitor, its derivatives exhibit a wide range of biological activities. For example, anti‐inflammatory,6 antibacterial,7 antimycotic,8 as well as cytostatic9, 10 imidazoles have been described. Imidazolium salts can be used as ionic liquids or as precursors of versatile N‐heterocyclic carbenes 11.…”