An Improved Procedure for the Large Scale Preparation of 2-Chloro-4,6-dimethoxy-1,3,5-triazine

Pd(0)/Xantphos-Catalyzed Benzylic C(sp3)-O Arylation of Benzyl Heteroaryl Ethers: Reduction of Pd(II) to Pd(0) by Xantphos

Herein, we report the synthesis of 1,1-diarylmethanes via palladium-catalyzed benzylic C(sp3)-O arylation of benzyl alcohol derivatives. An efficient, straightforward approach to synthesizing Pd(0)(xantphos)2 was developed through in situ reduction of Pd(II) to Pd(0) with the bidentate tertiary phosphine xantphos, which proved to be a highly active precatalyst in the Suzuki-Miyaura cross-coupling reaction of benzyl heteroaryl ethers.

Polymer Coated Oncolytic Adenovirus to Selectively Target Hepatocellular Carcinoma Cells

Despite significant advances in chemotherapy, the overall prognosis of hepatocellular carcinoma (HCC) remains extremely poor. HCC targeting strategies were combined with the tumor cell cytotoxicity of oncolytic viruses (OVs) to develop a more efficient and selective therapeutic system. OVs were coated with a polygalactosyl-b-agmatyl diblock copolymer (Gal₃₂-b-Agm₂₉), with high affinity for the asialoglycoprotein receptor (ASGPR) expressed on the liver cell surface, exploiting the electrostatic interaction of the positively charged agmatine block with the negatively charged adenoviral capsid surface. The polymer coating altered the viral particle diameter (from 192 to 287 nm) and zeta-potential (from -24.7 to 23.3 mV) while hiding the peculiar icosahedral symmetrical OV structure, as observed by TEM. Coated OVs showed high potential therapeutic value on the human hepatoma cell line HepG2 (cytotoxicity of 72.4% ± 4.96), expressing a high level of ASGPRs, while a lower effect was attained with ASPGR-negative A549 cell line (cytotoxicity of 54.4% ± 1.59). Conversely, naked OVs showed very similar effects in both tested cell lines. Gal₃₂-b-Agm₂₉ OV coating enhanced the infectivity and immunogenic cell death program in HepG2 cells as compared to the naked OV. This strategy provides a rationale for future studies utilizing oncolytic viruses complexed with polymers toward effective treatment of hepatocellular carcinoma.

Facile Synthetic Protocols for the preparation of New Impurities in Pemetrexed Disodium Heptahydrate as an Anti-Cancer Drug

A facile synthetic protocols were employed to prepare process-related impurities associated with the synthesis of pemetrexed disodium heptahydrate, Alimta. The research work is described for the development of the novel synthetic methods and their structure elucidation of Pemetrexed glutamide, N-methyl pemetrexed, and N-methyl pemetrexed glutamide impurities. The listed impurities were deduced through spectral analysis such as 1H-NMR, 13CNMR, and HRMS. The target compounds can be used as the reference substances for the quality control.

Role of linkers in tertiary amines that mediate or catalyze 1,3,5-triazine-based amide-forming reactions

We studied 1,3,5-triazine-based amide-forming reactions that are mediated or catalyzed by various tert-amines. The representative tert-amine was trimethylamine, which has amido, 1,2,3-triazolyl, aryl, and alkyl linkers. It was found that electron-deficient aryl and heteroaryl linkers, particularly 1,2,3-triazolyl linkers, are superior. On the basis of our findings, we synthesized ligand catalysts, including a 1,2,3-triazolyl linker that connects a protein ligand to a trimethylamine moiety, and found that fluorescent-labeling of a targeting protein using the ligand catalysts proceeded in good yields.

Nickel-catalyzed Suzuki-Miyaura coupling of heteroaryl ethers with arylboronic acids

Nickel-catalyzed Suzuki-Miyaura coupling of heteroaryl ethers with arylboronic acids was described. Selective activation of the phenol C-O bonds was achieved by converting them into the corresponding aryl 2,4-dimethoxy-1,3,5-triazine-6-yl ethers, in which aryl C-O bond could be selectively cleaved with inexpensive, air-stable NiCl2(dppf) as a catalyst. Coupling of these readily accessible heteroaryl ethers proved tolerant of extensive functional groups.

Study on 1,3,5-triazine chemistry in dehydrocondensation: gauche effect on the generation of active triazinylammonium species

The reaction of 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) with various nitrogen-containing compounds, particularly tertiary amines (tert-amines), has been studied for the preparation of 2-(4,6-dimethoxy-1,3,5-triazinyl)trialkylammonium salts [DMT-Am(s)]. DMT-Ams derived from aliphatic tert-amines exhibited activity for the dehydrocondensation between a carboxylic acid and an amine to form an amide in a model reaction. Based on a conformational analysis of DMT-Ams and tert-amines by NMR and X-ray diffraction methods, we concluded that a β-alkyl group maintained in a gauche relationship with the nitrogen lone pair of tert-amines significantly hinders the approach of CDMT to the nitrogen. Thus, trimethylamine and quinuclidine without such alkyl groups readily react with CDMT whereas triethylamine, possessing two or three such gauche β-alkyl groups in the stable conformations, does not react at all. The theory of "gauche β-alkyl group effect" proposed here provides useful guidelines for the preparation of DMT-Ams possessing various tertiary amine moieties. An investigation of the dehydrocondensation activity of tert-amines in a CDMT/tert-amine system that involves in situ generation of DMT-Am, showed that the gauche effect of the β-alkyl group becomes quite pronounced; the yield of the amide decreases significantly with tert-amines possessing an unavoidable gauche β-alkyl group. Thus, the tert-amine/CDMT systems are useful for judging whether tert-amines can readily react with CDMT without isolation of DMT-Ams.

Helical Porous Protein Mimics Self-Assembled from Amphiphilic Dendritic Dipeptides

This manuscript reports the synthesis and the self-assembly of (4-3,4,5-3,5)nG2-CH2-Boc-l-Tyr-l-Ala-OMe dendritic dipeptides (n = 12, 16). These dendritic dipeptides self-assemble both in solution and in solid states into helical porous supramolecular columns that mimic porous transmembrane proteins. These supramolecular assemblies provide also a new class of tubular supramolecular polymers.

Development of a Simple System for Dehydrocondensation Using Solid-Phase Adsorption of a Water-Soluble Dehydrocondensing Reagent (DMT-MM)

It has been indicated that hydrophilic solid powder to which aqueous solution of a novel dehydrocondensing reagent DMT-MM is adsorbed becomes a simple solid-phase dehydrocondensing reagent of low cost. Reaction in a liquid--liquid biphasic system on the surface of a solid phase with a large area was accelerated by suspending this powder in a dichloromethane solution of a carboxylic acid and an amine to be condensed. The reaction was rapid with a high yield despite the heterogeneity of the system. Like general solid-phase reagents, a hydrophobic carboxamide alone could be isolated at a relatively high purity only by filtration of the resulting suspension of reaction mixture.

Emission color tuning in AlQ3 complexes with extended conjugated chromophores

[reaction: see text] A new method for the synthesis of 5-arylethynyl-8-hydroxyquinoline ligands using Sonogashira-Hagihara coupling was developed. The electronic nature of arylethynyl substituents affects the emission color and quantum yield of the resulting Al(III) complex. Photophysical properties of the metallocomplexes correspond to the electron-withdrawing/-donating character of the arylethynyl substituents. Optical properties of such Al(III) complexes correlate with the Hammett constant values of the respective substituents. This strategy offers a powerful tool for the preparation of electroluminophores with predictable photophysical properties.

A novel generation of coupling reagents. Enantiodifferentiating coupling reagents prepared in situ from 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and chiral tertiary amines

Coupling of racemic N-protected amino acids with amino components by means of 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) in the presence of chiral tertiary amines such as strychnine, brucine, and sparteine proceeds enantioselectively, affording appropriate amides or dipeptides in 69-85% yield. The configuration of the preferred enantiomer and enantiomeric enrichment depend on the structures of the amine and carboxylic acid. Calculated Kagan enantioselectivity parameters (s) are in the range 1.6-195. Chiral triazinylammonium chlorides formed in situ from CDMT and chiral tertiary amines are postulated as reactive intermediates involved in the process of enantioselective activation of N-protected amino acids.

Triazine-based condensing reagents

The synthesis, properties, and application of condensing reagents derived from 1,3,5-triazines are described. The mechanism of activation of carboxylic function, structure of reactive intermediates, and mechanism of acylation of nucleophiles are presented. The synthetic versatility of mono- and bifunctional reagents for syntheses in solution, triazine-based immobilized reagents, chiral triazines for enantiodifferentiating syntheses, are discussed. The scope and limitation of the synthetic utility of triazine reagents in the preparation of heterocyclic compounds, amides, esters, oligopeptides-including large-scale syntheses and use in the combinatorial chemistry-is demonstrated.