One-pot synthesis of N-benzyl-2-aminobenzoic acid, via ring opening of isatoic anhydride derivative, and its antibacterial screening

2-(N-Benzyl) amino benzoic acid is a bifunctional molecule that could be produced from the reaction between isatoic anhydride and aryl halide. Analogues and derivatives of isatoic anhydride have wide application in pharmaceuticalsincluding antibacterial activity. The aim of this study is to synthesize, characterize and screen N-benzyl isatoic anhydride and 2-(N-benzyl) amino benzoic acid for antibacterial activity. The reaction of isatoic anhydride and benzyl bromide in the presence of potassium carbonate in DMSO at room temperature yielded N-benzyl isatoic anhydride, which under hydrolysis yielded 2-(N-benzyl) amino benzoic acid in which the anhydride ring is opened up. This compound was screened against Gram positive and negative bacteria. Moderate yield of 2-(N-benzyl) amino benzoic acid, a yellow crystal (melting point of 160-162oC, percentage yield 65 %, Rf 0.19) formed by ring opening of N-benzyl isatoic anhydride. The compound showed no antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas pyocyanea, Salmonella typhimurium, Klebsiella aeruginosa and Bacillus subtilis. 2-(N-benzyl)amino benzoic was synthesized, characterized and showed no activity against bacteria.

Synthesis and plant growth activity of 2-(4-oxochromen-3-yl)benzothiazolium and -benzoxazolium bromides

A facile synthesis of novel 2-(4-oxochromen-3-yl) benzothiazolium bromides 4 and benzoxazolium bromide 5 using the one-pot condensation of substituted 4-oxochromene-3-carboxaldehydes 1 with 2-methylbenzothiazole (2a) or 2-methylbenzoxazole (2b) and benzyl bromide is described. The effects of benzothiazolium bromides 4 on the growth stimulation of the cucumber and retardant activity on corn seedlings were investigated. They inhibited growth of cucumber (root and hypocotyl) and shoots of corn at the range of 10 – 100 ppm and stimulated at 0.1 – 1 ppm concentrations.

Synthesis of heterocyclic ring (1,2,4-triazole) as polystyrene photo stabilizer

New heterocyclic compounds contain triazole ring (play very important role in photostabilization as UV absorber) synthesized by reaction between the di Schiff base (compound 3) with aromatic alkyl halide (Benzyl bromide) and shows there activity as photostabilizer for polystyrene through exposure to the UV-Light (300 hours). Finally Infrared spectroscopy, 1H-NMR, 13C-NMR and instrumental methods were used to characterize products and their structures.

Effective End-Group Modification of Star-Shaped PNVCL from Xanthate to Trithiocarbonate Avoiding Chemical Crosslinking

In this study, six-arm star-shaped poly(N-vinylcaprolactam) (PNVCL) polymers prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization were subjected to aminolysis reaction using hexylamine. Chemically crosslinked gels or highly end-functionalized star polymers can be obtained depending mainly on the type of solvent used during the transformation of the RAFT functional group. An increase in the viscosity of the solution was observed when the aminolysis was carried out in THF. In contrast, when the reaction was conducted in dichloromethane, chain-end thiol (PNVCL)6 star polymers could be obtained. Moreover, when purified (PNVCL-SH)6 star polymers are in contact with THF, the gelation occurs in just a few minutes, with an obvious increase in viscosity, to form physical gels that become chemically crosslinked gels after 12 h. Interestingly, when purified (PNVCL-SH)6 star polymers were stirred in distilled water, even at high aqueous solution concentration (40 mg/mL), there was no increase in the viscosity or gelation, and no evident gels were observed. The analysis of the hydrodynamic diameter (Dh) by dynamic light scattering (DLS) did not detect quantifiable change even after 4 days of stirring in water. On the other hand, the thiol groups in the (PNVCL-SH)6 star polymers were easily transformed into trithiocarbonate groups by addition of CS2 followed by benzyl bromide as demonstrated by UV-Vis spectroscopical analysis and GPC. After the modification, the (PNVCL)6 star polymers exhibit an intense yellow color typical of the absorption band of trithiocarbonate group at 308 nm. To further demonstrate the highly effective new trithiocarbonate end-functionality, the PNVCL polymers were successfully chain extended with N-isopropylacrylamide (NIPAM) to form six-arm star-shaped PNIPAM-b-PNVCL block copolymers. Moreover, the terminal thiol end-functionality in the (PNVCL-SH)6 star polymers was linked via disulfide bond formation to l-cysteine to further demonstrate its reactivity. Zeta potential analysis shows the pH-responsive behavior of these star polymers due to l-cysteine end-functionalization. By this using methodology and properly selecting the solvent, various environment-sensitive star polymers with different end-groups could be easily accessible.

Photoredox Catalyzed Ring-Opening Addition Reaction Between Benzyl Bromides and Cyclic Ethers

A novel nucleophilic reaction between cyclic ethers and benzyl bromides is achieved under photoredox catalysis. The reaction proceeds through a single electron transfer (SET) pathway rather than a common SN2 mechanism. By two steps of reduction and oxidation, a benzyl bromide heterolyzes to give a carbocation and bromide ion under mild conditions, and then a cyclic ether captures both the carbocation and bromide ion to afford the addition product.

Atom Transfer Radical Polymerization of Styrene and Acrylates: Effects of Catalyst, Ligand, Solvent, and Initiator

Well-defined polystyrenes were successfully prepared by the CuX/(dN)bpy or CuX/ PMDETA catalyzed atom transfer radical polymerization of styrene using 1-phenylethyl bromide (1-PEBr) or benzyl bromide (BnBr) as initiators. We found that the CuX/PMDETA catalyzed ATRP of styrene proceeded faster than CuX/(dN)bpy catalyzed counterpart in bulk, diphenyl ether (DPE) and anisole. Using CuX/(dN)bpy catalyst, well-defined polystyrenes were obtained with good chain-end functionalities and low polydispersity (Mw/Mn <1.5) compared to CuX/PMDETA catalyst. The CuBr/PMDETA catalyzed ATRP of n-butyl acrylate (nBA), n-butyl methacrylate (nBMA), and tert-butyl methacrylate (tBMA) were also proceeded in a controlled manner. The molecular structure and molecular weight of polymers were determined by proton nuclear magnetic resonance (1H NMR) spectroscopy and size exclusion chromatography (SEC), respectively.

Bioinspired Total Synthesis of Marine Anti-Cancer Meroterpenoids Dysideanone B and Dysiherbol A and Structure Revision of Dysiherbol A

Our recent progress on the total synthesis of marine anti-cancer sesquiterpene quinone/hydroquinone dysideanone B and dysiherbol A was briefly highlighted. This success relied on some key transformations. The union of the terpene and quinone/hydroquinone moieties was realized through a site and stereoselective α-position alkylation of Wieland–Miescher ketone derivative with a bulky benzyl bromide. The 6/6/6/6-tetracycle of dysideanone B was constructed using an intramolecular radical cyclization and the 6/6/5/6-fused core structure of dysiherbol A was forged by an intramolecular Heck reaction, respectively. The possible origin of ethoxy group in dysideanone B was revealed by mimicking the isolation conditions at a late-stage. The structure of dysiherbol A was revised through the total synthesis of this natural product. Schmalz’s synthesis of dysiherbol A was also included.

Experimental and Computational Studies on N-alkylation Reaction of N-Benzoyl 5-(Aminomethyl)Tetrazole

The N-alkylation reaction of N-benzoyl 5-(aminomethyl)tetrazole (5-AMT) with benzyl bromide was carried out in the presence of K2CO3 as a base. Two separable regioisomers were obtained, thus their purification led to determine the proportion of each of them, and their structures were attributed essentially based on 1H and 13C NMR spectroscopy in addition to the elemental analysis and MS data. In order to confirm the results obtained at the synthesis level, a computational study was carried out by application of density functional theory (DFT) using the Becke three-parameter hybrid exchange functional and the Lee-Yang-Parr correlation functional (B3LYP).

The Catalytic Activity of Carbon-Supported Cu(I)-Phosphine Complexes for the Microwave-Assisted Synthesis of 1,2,3-Triazoles

A set of Cu(I) complexes with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo-[3.3.1]nonane (DAPTA) phosphine ligands viz. [CuX(κP-DAPTA)3] (1: X = Br; 2: X = I) and [Cu(μ-X)(κP-DAPTA)2]2 (3: X = Br; 4: X = I) were immobilized on activated carbon (AC) and multi-walled carbon nanotubes (CNT), as well as on these materials after surface functionalization. The immobilized copper(I) complexes have shown favorable catalytic activity for the one-pot, microwave-assisted synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition reaction (CuAAC). The heterogenized systems with a copper loading of only 1.5–1.6% (w/w relative to carbon), established quantitative conversions after 15 min, at 80 °C, using 0.5 mol% of catalyst loading (relative to benzyl bromide). The most efficient supports concerning heterogenization were CNT treated with nitric acid and NaOH, and involving complexes 2 and 4 (in the same order, 2_CNT-ox-Na and 4_CNT-ox-Na). The immobilized catalysts can be recovered and recycled by simple workup and reused up to four consecutive cycles although with loss of activity.