Oxoazabenzo[de]anthracenes Conjugated to Amino Acids: Synthesis and Evaluation as DNA-Binding Antitumor Agents

Electrochemical oxidative cyclization of N-allylamides for the synthesis of CF3-containing benzoxazines and oxazolines

The introduction of trifluoromethyl (-CF3) groups into compounds is a common synthetic strategy in organic chemistry. Commonly used methods for introducing trifluoromethyl groups are limited by harsh reaction conditions, low regioselectivity, or the need for excess reagents. In this study, a facile electrochemical oxidative and radical cascade cyclization of N-(2-vinylphenyl)amides for the synthesis of CF3-containing benzoxazines and oxazolines was obtained. This sustainable protocol features inexpensive and durable electrodes, a wide range of substrates, diverse functional group compatibility under transition-metal-free, external-oxidant-free, and additive-free conditions, and can be applied in an open environment.

Conjugation as a Tool in Therapeutics: Role of Amino Acids/Peptides-Bioactive (Including Heterocycles) Hybrid Molecules in Treating Infectious Diseases

Peptide-based drugs are gaining significant momentum in the modern drug discovery, which is witnessed by the approval of new drugs by the FDA in recent years. On the other hand, small molecules-based drugs are an integral part of drug development since the past several decades. Peptide-containing drugs are placed between small molecules and the biologics. Both the peptides as well as the small molecules (mainly heterocycles) pose several drawbacks as therapeutics despite their success in curing many diseases. This gap may be bridged by utilising the so called 'conjugation chemistry', in which both the partners are linked to one another through a stable chemical bond, and the resulting conjugates are found to possess attracting benefits, thus eliminating the stigma associated with the individual partners. Over the past decades, the field of molecular hybridisation has emerged to afford us new and efficient molecular architectures that have shown high promise in medicinal chemistry. Taking advantage of this and also considering our experience in this field, we present herein a review concerning the molecules obtained by the conjugation of peptides (amino acids) to small molecules (heterocycles as well as bioactive compounds). More than 125 examples of the conjugates citing nearly 100 references published during the period 2000 to 2022 having therapeutic applications in curing infectious diseases have been covered.

Transition-metal-free synthesis of trifluoromethylated benzoxazines via a visible-light-promoted tandem difunctionalization of o-vinylanilides with trifluoromethylsulfinate

A Umemoto's reagent-free and cost-effective method for synthesis of trifluoromethylated benzoxazines by 9,10-phenanthrenedione visible-light photocatalysis is described in this article.

Catalyst- and Additive-Free Approach to Constructing Benzo-oxazine, Benzo-oxazepine, and Benzo-oxazocine: O Atom Transfer and C═O, C-N, and C-O Bond Formation at Room Temperature

An exclusive synthesis of benzo-oxazine, benzo-oxazepine, and benzo-oxazocine from aryl propanal and 2-(hydroxyamino)phenyl alcohol under metal-free conditions is described. O atom transfer and formation of new C═O, C-N, and C-O bonds occur at room temperature to form six-, seven-, and eight-membered heterocycles under one-pot reaction conditions without using an external oxidant and base. The photophysical properties are studied using ultraviolet-visible absorption and photoluminescence. The mechanistic elucidation is well supported by control experiment and literature precedents.

Persulfate-activated charcoal mixture: an efficient oxidant for the synthesis of sulfonated benzo[d][1,3]oxazines from N-(2-vinylphenyl)amides and thiols in aqueous solution

A series of 2,4-aryl-4-((arylsulfonyl)methyl)-4H-benzo[d][1,3]oxazines in good to excellent yields have directly been obtained from N-(2-vinylphenyl)amides and thiols by employing a mixture of K₂S₂O₈-activated charcoal in aqueous acetonitrile solution at 50 °C. A plausible mechanism for the reaction is reported. It reveals that the reaction follows a radical pathway and the persulfate has been the oxygen source for formation of the sulfone group in the products. It is worth mentioning that this protocol utilizes an easily accessible K₂S₂O₈-activated charcoal mixture and thiols, respectively, as an oxidant and sulfonylating precursors for the first time.

Efficient Synthesis of Substituted 2-(4H-1,3-benzoxazin-2-yl)Phenols via a Pseudo Three-Component Reaction

An efficient pseudo three-component reaction between substituted 2-hydroxybenzaldehydes and ammonium acetate for the preparation of substituted 2-(4 H-1,3-benzoxazin-2-yl)phenols in moderate to good yields (70-80%) was developed. The structure of a typical product was confirmed by X-ray crystallography.

A distal vinyl shift (DVS) through quadruple domino reaction: synthesis of N-vinyl benzoheterocyclic scaffolds

An unprecedented Distal Vinyl Shift (DVS) through quadruple domino reaction has been disclosed via the synthesis of N-vinyl benzoheterocyclic scaffolds.

Base-mediated [2 + 4] cycloadditions of in situ formed azaoxyallyl cations with N-(2-chloromethyl)aryl amides

A base-mediated [2 + 4] annulation of in situ formed azaoxyallyl cations with in situ generated aza-oQMs has been realized.

Amino acids/peptides conjugated heterocycles: A tool for the recent development of novel therapeutic agents

Amino acids/peptide conjugated heterocycles represent an important class of therapeutical agents. Biologically active heterocycles are conjugated with amino acids or peptides to increase the drug resistance. Furthermore, the amino acid/peptide based drugs have low toxicity, ample bioavailability and permeability, modest potency and good metabolic and pharmacokinetic properties. Synthetic amino acid/peptides based heterocyclic conjugates constitute a promising choice for the development of new, less toxic and safer conventional pharmaceutical drugs in the near future. In this review, we discuss and highlight the recent findings of the structural features that encourage biological applications of amino acid/peptides based conjugates.

Synthesis and Fungicidal Activity of 1-(Carbamoylmethyl)-2-aryl-3,1-benzoxazines

A series of new 1-(carbamoylmethyl)-2-aryl-3,1-benzoxazines were prepared in moderate to good yields by BF₃·OEt₂-catalyzed reactions of aromatic aldehydes with 2-(N-substituted carbamoylmethylamino)benzyl alcohols. The structures of the target compounds were confirmed by IR, ¹H-NMR, ¹³C-NMR, and elemental analyses. The fungicidal activities of the target compounds against plant fungi were preliminarily evaluated, and some of them exhibited good activity.

Preparing Mn(iii) salen-type Schiff base complexes using 1,3-oxazines obtained by Mannich condensation: towards removing ortho-hydroxyaldehydes

Synthesis of Mn(iii)-salen type Schiff base complexes from 1,3-oxazines obtained from Mannich condensation. This method eliminates the restrictions on the use ofortho-hydroxyaldehydes.

Synthesis of benzo[1,3]oxazines via copper(i)-catalyzed cascade annulation of nitriles, aldehydes and diaryliodonium salts

A copper(i)-catalyzed one-pot [2 + 2 + 2] cascade annulation reaction of diaryliodoniums, nitriles, and aldehydes has been developed for the efficient synthesis of 2,4-substituted benzoxazine derivatives.

Visible-light-induced photocatalytic oxytrifluoromethylation of N-allylamides for the synthesis of CF3-containing oxazolines and benzoxazines

A visible-light-induced photocatalytic oxytrifluoromethylation reaction of N-allylamides has been developed for the efficient synthesis of CF3-containing oxazolines and benzoxazines under mild reaction conditions.

Copper-catalysed cross-coupling affected by the Smiles rearrangement: a new chapter on diversifying the synthesis of chiral fluorinated 1,4-benzoxazine derivatives

Synthesis of novel derivatives of fluorinated benzoxazines was achieved through the Smiles rearrangement. The gauche conformation of selected precursors enabled the reaction to occur at room temperature at yields of 90%.

Palladium-catalyzed highly regioselective 6-exo-dig cyclization and alkenylation of ortho-ethynylanilides: the synthesis of polyene-substituted benzo[d][1,3]oxazines

A Pd-catalyzed highly regioselective 6-exo-dig cyclization/alkenylation reaction of ortho-ethynylanilides has been developed.

Copper-catalyzed trifluoromethylation of alkenes: synthesis of trifluoromethylated benzoxazines

A ligand and base free copper catalyzed method has been developed for the construction of trifluoromethylated benzoxazines by using Umemoto's reagent.

Intramolecular C–O/C–S bond insertion of α-diazoesters for the synthesis of 2-aryl-4H-benzo[d][1,3]oxazine and 2-aryl-4H-benzo[d][1,3]thiazine derivatives

An intramolecular C–O/C–S insertion of 2-(2-arylamidophenyl)-2-diazoacetate/2-diazo-2-(2-arylthioamidophenyl)acetate is achieved using 10 mol% Cu(OTf)₂ to generate benzoxazines/benzothiazines.

Synthesis and evaluation as antitumor agents of 1,4-naphthohydroquinone derivatives conjugated with amino acids and purines

We report on the synthesis of two series of 1,4-naphthohydroquinone derivatives conjugated with amino acids (Gly, Ala, Phe, and Glu) and with substituted purines linked by an aliphatic chain. The compounds were obtained through Diels-Alder cycloaddition between myrcene and 1,4-benzoquinone and evaluated in vitro for their cytotoxicity (GI50 ) against cultured human cancer cells of A-549 lung carcinoma, HT-29 colon adenocarcinoma, and MCF-7 breast carcinoma. The GI50 values found for some hydroquinone-amino acid and hydroquinone-purine hybrids against MCF-7 are in an activity range comparable to that of the reference drug doxorubicin.

Synthesis, cytotoxicity and DNA binding of oxoazabenzo[de]anthracenes derivatives in colon cancer Caco-2 cells

New oxoazabenzo[de]anthracenes derivatives were synthesised and characterised. Their interactions with calf thymus DNA were studied by UV spectrophotometric analysis and a competitive ethidium bromide displacement assay. Cytotoxicity was determined by MTT assay, against colon adenocarcinoma (Caco-2 cells). Among all the oxoazabenzo[de]anthracenes derivatives reported herein only the piperidino derivative exhibited strong DNA binding properties and cytotoxic activity with IC₅₀ values in the range of 16 ± 1.5 μM (72-h treatment). In addition, the piperidino derivative did not directly inhibit topoisomerase I and topoisomerase II enzymes. The results confirm that the presence of the oxoazabenzo[de]anthracenes together with the piperidino functionality is crucial in exerting DNA binding and cytotoxic properties, hence demonstrating promise as a chemical scaffold for further development of new anticancer agents.

CuCl/DABCO/4-HO-TEMPO-catalyzed aerobic oxidative synthesis of 2-substituted quinazolines and 4H-3,1-benzoxazines

The Cu/N-ligand/TEMPO catalytic system was first applied to the aerobic oxidative synthesis of heterocycles. As demonstrated, 2-substituted quinazolines and 4H-3,1-benzoxazines were synthesized efficiently from the one-pot reaction of aldehydes with 2-aminobenzylamines and 2-aminobenzyl alcohols, respectively, by employing CuCl/DABCO/4-HO-TEMPO as the catalysts and oxygen as the terminal oxidant.

Anthracene based base-discriminating fluorescent oligonucleotide probes for SNPs typing: Synthesis and photophysical properties

2- and 9-Anthracenecarboxamide labeled 2'-deoxyuridines were synthesized and their photophysical properties were examined. These oligonucleonucleotide probes are capable of detecting adenine base on a target DNA sequence. It was also found that 2-anthracene based oligonucleotide probe is more efficient than the corresponding 9-anthracene based oligonucleotide in the application for DNA chip based SNP detection, due to its longer emission wavelength and high fluorescence intensity.

DNA binding properties and evaluation of cytotoxic activity of 9,10-bis-N-substituted (aminomethyl)anthracenes

The results of DNA binding properties for four selected N-substituted 9,10-bis(aminomethyl)anthracenes are presented. DNA binding affinities were studied using UV-vis and fluorescence spectrophotometric titrations, CD spectroscopy, denaturation transition temperature (Tm) measurements and AM1 quantum chemical calculations. The results obtained indicate that the anthracene products intercalate into the stacked base pairs of DNA with binding constants, K, in the range 1.3-10.9 x 10(5)M(-1) and the binding site size in DNA-base pairs, n, extending over the range 2.4-4.6. Tm values increased in the presence of the anthryl probes, thereby reflecting an increased stability of the calf-thymus (CT) DNA double helix and rendering agreement with the spectrometric titration results. The synthesized compounds were tested against L1210 and HeLa tumor cell lines wherein the HeLa cells appeared to be more sensitive than the L1210 cells. 9,10-Bis{[2-(piperazin-1-yl)ethyl]aminomethyl}anthracene exhibited the highest activity of the tested compounds. Our findings were compared with those of a control drug bisantrene.