Overview on the synthetic routes to nicotine nitriles

New 6′-Amino-5′-cyano-2-oxo-1,2-dihydro-1′H-spiro[indole-3,4′-pyridine]-3′-carboxamides: Synthesis, Reactions, Molecular Docking Studies and Biological Activity

The purpose of this work was to prepare new isatin- and monothiomalondiamide-based indole derivatives, as well as to study the properties of the new compounds. The four-component reaction of 5-R-isatins (R = H, CH3), malononitrile, monothiomalonamide (3-amino-3-thioxo- propanamide) and triethylamine in hot EtOH yields a mixture of isomeric triethylammonium 6′-amino-3′-(aminocarbonyl)-5′-cyano-2-oxo-1,2-dihydro-1′H- and 6′-amino-3′-(aminocarbonyl)- 5′-cyano-2-oxo-1,2-dihydro-3′H-spiro[indole-3,4′-pyridine]-2′-thiolates. The reactivity and structure of the products was studied. We found that oxidation of spiro[indole-3,4′-pyridine]-2′-thiolates with DMSO-HCl system produced only acidification products, diastereomeric 6′-amino-5′-cyano-5-methyl-2-oxo-2′-thioxo-1,2,2′,3′-tetrahydro-1′H-spiro-[indole-3,4′-pyridine]- 3′-carboxamides, instead of the expected isothiazolopyridines. The alkylation of the prepared spiro[indole-3,4′-pyridine]-2′-thiolates upon treatment with N-aryl α-chloroacetamides and α-bromoacetophenones proceeds in a regioselective way at the sulfur atom. In the case of α-bromoacetophenones, ring-chain tautomerism was observed for the S-alkylation products. According to NMR data, the compounds consist of a mixture of stereoisomers of 2′-amino-6′-[(2-aryl-2-oxoethyl)thio]-3′-cyano-2-oxo-1′H-spiro[indoline-3,4′-pyridine]-5′-carboxamides and 5′-amino-3′-aryl-6′-cyano-3′-hydroxy-2-oxo-2′,3′-dihydrospiro[indoline-3,7′-thiazolo[3,2-a]pyridine]-8′-carboxamides in various ratios. The structure of the synthesized compounds was confirmed by IR spectroscopy, HRMS, 1H and 13C DEPTQ NMR studies and the results of 2D NMR experiments (1H-13C HSQC, 1H-13C HMBC). Molecular docking studies were performed to investigate suitable binding modes of some new compounds with respect to the transcriptional regulator protein PqsR of Pseudomonas aeruginosa. The docking studies revealed that the compounds have affinity for the bacterial regulator protein PqsR of Pseudomonas aeruginosa with a binding energy in the range of −5.8 to −8.2 kcal/mol. In addition, one of the new compounds, 2′-amino-3′-cyano-5-methyl-2-oxo-6′-{[2-oxo-2-(p-tolylamino)ethyl]thio}-1′H-spiro-[indoline-3,4′-pyridine]-5′-carboxamide, showed in vitro moderate antibacterial effect against Pseudomonas aeruginosa and good antioxidant properties in a test with 1,1-diphenyl-2-picrylhydrazyl radical. Finally, three of the new compounds were recognized as moderately active herbicide safeners with respect to herbicide 2,4-D in the laboratory experiments on sunflower seedlings.

Systematic Engineering of Escherichia coli for Efficient Production of Nicotinamide Mononucleotide From Nicotinamide

Research studies on NAD⁺ have proven its crucial role in aging and disease. Nicotinamide mononucleotide (NMN), as the key intermediate of NAD⁺, plays a significant role in supplying and maintaining NAD⁺ levels. In the present study, a biocatalytic method for the efficient synthesis of NMN was established. First, Escherichia coli was systematically modified to make it more conducive to the biosynthesis and accumulation of NMN. Next, the performance of nicotinamide phosphoribosyltransferase from Vibrio bacteriophage KVP40 (VpNadV) was determined, which has the best catalytic activity to produce NMN from nicotinamide. The accumulation of extracellular NMN was further increased after the introduction of an NMN transporter. Fine-tuning of gene expression and copy number led to the synthesis of NMN at the yield of 2.6 g/L at the shake flask level. The introduction of a nicotinamide transporter, BcniaP, could not obviously increase the production of NMN at the shake flask level, but it decreased the production of NMN at the bioreactor level. Finally, the titer of NMN reached 16.2 g/L with a conversion ratio of 97.0% from nicotinamide, both of which are highest according to currently available reports. The fed-batch fermentation with direct supplementation of nicotinamide could facilitate the industrial-scale production of NMN compared to that achieved by the whole-cell catalysis process. These results also represent the highest reported yield of NMN synthesized from nicotinamide in E. coli.

Synthesis and Some Properties of New 5-Hydroxy-2-[(hetarylthio)methyl]-4H-pyran-4-ones

Abstract

The reaction of 2-thioxoazines with chlorokojic acid in the presence of KOH in DMF led to the formation of new hybrid molecules containing fragments of kojic acid and azaheterocycle linked by the SCH2 spacer. In silico prediction of bioavailability parameters was carried out, possible protein targets were predicted by the protein ligand docking method.

Rh(III)-Catalyzed [5 + 1] Annulation of Indole-enaminones with Diazo Compounds To Form Highly Functionalized Carbazoles

A novel Rh(III)-catalyzed C-H activation/annulation cascade of indole-enaminones with diazo compounds was reported to construct diversely functionalized carbazole frameworks. The most notable characteristic is that this transformation could smoothly furnish a novel [5 + 1] cyclization product with good to excellent yields (up to 95%), accompanied by the thorough removal of acetyl and N,N-dimethyl groups of two substrates from the target products, rather than the normally expected [4 + 2] cyclization products.