Facile,one-pot synthesis of new phenanthridine derivatives through 1,4-dipolar cycloaddition of phenantridine,activated acetylenes,and aromatic aldehydes

A facile, one-pot synthesis of new phenanthridine derivatives by a three-component reaction between phenantridine, dialkyl acetylenedicarboxylates（DAADs）, and aromatic aldehydes is described. The reaction is characterized by mild conditions, high selectivity, and tolerance to various functional groups.     

A Garratt-Braverman cyclization route towards the synthesis of phenanthridine derivatives and their DNA-binding studies

Garratt-Braverman cyclization has been employed to synthesize a series of dihydroisofuran fused phenanthridine derivatives. The established protocol proposes a simpler synthetic alternative to have access to these therapeutically relevant cytotoxic scaffolds. Single crystal X-ray data unambiguously confirmed the structures of the synthesized phenanthridine derivatives. UV–Vis absorption titration with calf-thymus DNA followed by fluorescence-based competitive ethidium bromide displacement assay established the synthesized target compounds as potent DNA-intercalating agents with intrinsic binding constant of the range 10³-10⁵. Results obtained from the molecular docking further justified the spectroscopically obtained results.     

Syntheses of phenanthridines and benzophenanthridines by intramolecular ortho-arylation of aryl amide ions with aryl halides via SRN1 reactions

The photostimulated reaction of N-(2-halo-benzyl)aryl amines with t-BuOK in liquid ammonia affords fused azaheterocycles by the S_RN1 mechanism. The starting materials are easily obtained by the reaction of 2-halo-benzyl chloride and aromatic amines to prepare the secondary amines. Through this approach, phenanthridine (90%), 4-phenylphenanthridine (87%), benzo[a]phenanthridine (98%), and benzo[c]phenanthridine (84%) were synthesized.     

Bis-phenanthridinium–adenine conjugates as fluorescent and CD reporters for fine structural differences in ds-DNA/RNA and ss-RNA structures

Two structurally similar bis-phenanthridinium–adenine conjugates (equipped with one or two adenines, respectively), exhibiting strong ds-DNA/RNA groove binding, revealed ratiometric fluorescent recognition of alternating AT-DNA with respect to other ds-DNA/RNA and ss-RNA. Further, CD spectra pattern of adenine–bis-phenanthridinium conjugate/polynucleotide complexes strongly depended on polynucleotide secondary structure. Attached adenine was essential for spectrophotometric recognition response, ds-DNA stabilisation and orientation of compounds regarding chiral DNA helix.     

Novel multicomponent reactions involving isoquinoline or phenanthridine and activated acetylenic ester in the presence of heterocyclic NH or 1,3-dicarbonyl compounds

Multicomponent reactions involving azines (phenanthridine or isoquinoline) and dimethyl acetylenedicarboxylate were undertaken in the presence of heterocyclic NH compounds (indole, 2-methyl indole, 3-methyl indole, carbazole and 3,6-dibromocarbazole) or 1,3-dicarbonyl compounds such as N,N'-dimethylbarbituric acid, 1,3-diethyl-2-thiobarbituric acid, acetylacetone, 1,3-diphenyl-1,3-propandione and cyclopentan-1,3-dione to generate enaminoesters in good yields.     

A single step synthesis of 6-aminophenanthridines from anilines and 2-chlorobenzonitriles

Biologically active 6-aminophenanthridines were prepared in a single step procedure: Metal amides in liquid ammonia promoted the condensation of anilines with 2-chloro-benzonitriles. 6-Aminophenanthridines were isolated in moderate yield.     

Three-component aza-Diels–Alder reactions using Yb(OTf)3 catalyst under conventional/ultrasonic techniques

The Yb(OTf)₃ catalyzed formal aza-Diels–Alder (or Povarov) reaction of cyclopentadiene and 1,3-cyclohexadiene with in situ-generated N-arylimines under conventional/ultrasonic techniques is herein described. This kind of three-component Povarov reaction results in quinoline and phenanthridine derivatives, which are important biological compounds.     

Cooperative C-H…N and C-H…π bonded molecular dimers of 5-aryl-7,8,13,14-tetrahydro-dibenzo[a,i]phenanthridine

As a result of our new high-yielding one-pot reaction procedure, the investigation on a series of heterocyclic 5-aryl-7,8,13,14-tetrahydro-dibenzo[a,i]phenanthridine compounds was possible and reported: 5-(4-ethyl-phenyl)-7,8,13,14-tetrahydro-dibenzo[a,i]phenanthridine, 5-(4-cyano-phenyl)-7,8,13,14-tetrahydro-dibenzo[a,i]phenanthridine, and 5-(2-ethyl-phenyl)-7,8,13,14-tetrahydro-dibenzo[a,i]phenanthridine. Half-chair conformation of alicyclic rings gives rise to a slightly folded structure of central tricyclic phenanthridine. The structure analysis showed the formation of a well-defined dimeric unit in the crystals. Dimeric association essentially involves cooperative C-H…N and C-H…π close contacts between molecules related by a center of inversion. The first two compounds are isomorphous with noticeable differences in steric packing. The first structural elucidation on 5-aryl-7,8,13,14-tetrahydro-dibenzo[a,i]phenanthridine compounds indicates the prominent mode of interactions, which has use in structure-based drug discovery and optoelectronic applications.     

β-Cyclodextrin modified filter paper based solid phase extraction–room temperature phosphorimetry for preconcentration and determination of nitrogen heterocyclic compounds in water samples

A highly selective method for the preconcentration and the determination of nitrogen heterocyclic compounds (NHCs) by solid phase extraction–room temperature phosphorimetry (SPE–RTP) was described. The β-cyclodextrin (β-CD) coated filter paper was synthesized and used as the SPE membrane and the substrate for the measurement of RTP emission of NHCs in water samples. The RTP characteristics of NHCs on the coated filter paper were studied. The conditions for the measurement of RTP intensities of NPAHs were discussed and optimized in detail. Several experimental parameters related to the preconcentration of NHCs on the coated filter paper were also examined. The experimental results showed that the β-CD coated filter paper could selectively extract NHCs containing three benzene rings with a high enrichment efficiency. The limit of detections of carbazole, 7,8-benzoquinoline and phenanthridine were found to be 9.1 × 10⁻¹⁴, 8.3 × 10⁻¹³ and 7.8 × 10⁻¹³ mol mL⁻¹, respectively. The proposed method was applied to the analysis of NHCs in water samples. The recoveries of carbazole, 7,8-benzoquinoline and phenanthridine in water samples was in the range of 86.1–109.3%.     

An expeditious synthesis of 6-aminophenanthridines

A simple synthesis of biologically active 6-aminophenanthridines was achieved by a Suzuki-Miyaura coupling reaction. Condensation of 2-(4,4,5,5-tetramethyl-1,3-dioxaborolan-2-yl)aniline with 2-chlorobenzonitriles afforded 6-aminophenanthridines useful as prions inhibitors in a mild one-step procedure. The intermediate 2-amino-2′cyanobiphenyls could not be isolated.