Degradation of aliphatic and aliphatic–aromatic co-polyesters by depolymerases from Roseateles depolymerans strain TB-87 and analysis of degradation products by LC-MS

The degradation activities of bacterium, Roseateles depolymerans TB-87 and its depolymerases Est-H and Est-L against aliphatic as well as aliphatic–aromatic co-polyesters, were investigated. Strain TB-87 and its enzymes exhibited an ability to degrade aliphatic and aliphatic–aromatic co-polyesters. Monomers produced as a result of degradation of aliphatic polyesters [poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA)] as well as aliphatic–aromatic co-polyester [poly(butylene succinate/terephthalate/isophthalate)-co-(lactate) (PBSTIL) by depolymerases Est-H and Est-L were investigated by liquid chromatography mass-spectrometry (LC-MS). Some common monomers like succinic acid and 1,4-butanediol were detected besides adipic acid and terephthalic/isophthalic acids as degradation products from PBSA and PBSTIL, respectively, whereas lactic acid was not detected. The succinic acid monomer was detected prior to adipic acid as a result of degradation of PBSA. The enzymes depolymerized PBS also into respective monomers. The analysis of PBSTIL degradation products revealed that enzymes easily degraded aliphatic segments as compared to aromatic segments and resulted in production of succinic acid prior to terephthalic and isophthalic acid. On the basis of these results, we speculate that both the enzymes Est-H and Est-L, attacked succinic acid segments (BS) first instead of adipic acid (BA) and terephthalic/isophthalic acid (BT or BI) segments of PBSA and PBSTIL, respectively. It is concluded from the results that R. depolymerans strain TB-87 can depolymerize aliphatic as well as aliphatic–aromatic co-polyesters; therefore, its enzymes can be applied in the process of biochemical monomer recycling.     

Synthesis and Crystal Structure of Some Novel 2-Aroylimino-3-aryl-4-phenyl-1,3-thiazolines

An efficient synthesis of some novel 2-aroylimino-3-aryl-4-phenyl-1,3-thiazolines was carried out by base-catalyzed cyclization of 1-aroyl-3-arylthioureas with acetophenone in the presence of bromine. The structures were confirmed by spectroscopic data, elemental analyses, and in one case (2t) by single-crystal X-ray diffraction data.     

Green Synthesis of Some New (Substituted Fluorobenzoylimino)-3-aryl-4-methyl-1,3-thiazolines

A series of 2-, 3-, and 4-substituted (fluorobenzoylimino)-3-aryl-4-methyl-1,3-thiazolines (2a–j) were synthesized in good yields by the base-catalyzed cyclization of corresponding 1-(fluorobenzoyl)-3-(fluorophenyl)thioureas (1a–j) with α-bromoacetone in water. Compared to the reactions in conventional nonaqueous solvents under inert anhydrous conditions, the aqueous medium provides a much cleaner, more efficient, and simpler method for synthesis.     

Novel N-(benzo[d]oxazol-2-yl)alkanamides; synthesis and carbonic anhydrase II inhibition studies

Carbonic anhydrase (CA II) inhibitors are very important therapeutic targets in drug design for treatment of neuropathic pain and in eradication of glaucoma, cancer, epilepsy, ulcer and obesity. In this study, some two2-substituted benzoxazoles ( 3a-j ) were developed as a new family of carbonic anhydrase II inhibitors by employing acyl thiourea chemistry via a simple and expedient protocol and evaluated for CA II inhibitor activity and radical scavenging ability. Compounds 3f and 3j were found to be the most potent inhibitors, with IC₅₀ values of 0.00564 and 0.00596 μM, respectively which are several times better than that of the standard, acetazolamide (IC₅₀ value 0.997 ± 0.0586 μM). Docking experiments were carried out against the carbonic anhydrase II crystal structure to better rationalize the inhibitory activities of these new structures. Moreover, the results of a DPPH radical scavenging assay showed that the antioxidant profile of compound 3i is superior to those of other derivatives. The results have revealed that derivatives 3f and 3j behave as CA-II inhibitors significantly better than standard and 3i has good anti-oxidation potential.     

RAFT polymerization of a novel activated ester monomer and conversion to a terpyridine‐containing homopolymer

Developing new materials with unique properties for nanotechnology applications, in general, and supramolecular polymers, in particular, lie at the heart of much ongoing research. In line with these efforts, we have been exploring polymers containing terpyridine (terpy) in the side chain. Here we report a new monomer that effectively undergoes reversible addition fragmentation chain transfer polymerization (RAFT) to yield high‐molecular‐weight (M_n) polymers with narrow polydispersity (PDI). The monomer is an N‐succinimide activated ester of p‐vinyl benzoic acid. Under RAFT conditions, poly(N‐succinimide p‐vinylbenzoate)s were generated, with M_n ranging between 44 and 61 kDa and PDI of 1.03–1.07. One of these homopolymers was reacted with an amine functionalized terpy, creating a new homopolymer containing terpy ligands on every monomer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5618–5625, 2007     

Total synthesis of achlisocoumarins I-II from Achlys triphylla

A concise and efficient total synthesis of achlisocoumarin I-II has been completed featuring a construction of the isocoumarin skeleton in a single step and the geranyl coupling with bromoarene ring at −10 °C exclusive of any chelating ligand.     

Synthesis, characterization and antimicrobial activity of some new 1-(fluorobenzoyl)-3-(fluorophenyl)thioureas

Synthesis of a variety of new 1-(isomeric fluorobenzoyl)-3-(isomeric fluorophenyl)thioureas (1a-t) was accomplished in two steps. The synthetic route involves the reaction of equimolar quantities of isomeric fluorobenzoyl chlorides with potassium thiocyanate in anhydrous acetone to afford the corresponding isothiocyantes in situ, followed by treatment with equimolar quantities of isomeric fluoroanilines. All of the synthesized compounds (1a-t) were screened for their in vitro antibacterial activity using Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aureginosa). The minimum inhibitory concentration (MIC) was also determined for the most active compounds. In vitro antifungal activity was also determined against the five fungal species (Rhizopus oryzae, Aspergillus tereus, Fusarium oxysporum, Aspergillus niger, Aspergillus fumigatus). In general, the antifungal activity of compounds was better than their antibacterial activity.     

Microwave promoted synthesis of some N-（4-methyl-3-tolylthiazol-2（3H）-ylidene） substituted benzamides

N-(4-Methyl-3-tolylthiazol-2(3H)-ylidene) substituted benzamides(2a-o) were synthesized in good to excellent yields by the base-catalyzed direct cyclization of corresponding 1-tolyl-3-aryl thioureas(1a-o) with 2-bromoacetone through microwave irradiation in a solvent-free medium.Compared to traditional thermal heating,microwave irradiation provides a much more cleaner,efficient and faster method for synthesis of the title compounds.     

Synthesis of 6,8-dihydroxy-3-(2'-acetyl-3',5'-dihydroxyphenyl)methylisocoumarin related to feralolide

Base-catalyzed self-condensation of 3,5-dimethoxyhomophthalic acid (2) directly furnished the 6,8-dimethoxy-3-(2'-carboxy-3',5'-dimethoxyphenyl)methylisocoumarin (3) which on successive treatment with oxalyl chloride, diazomethane and hydrolysis afforded the corresponding 2'-acetylisocoumarin (5). Complete demethylation of the latter yielded the 6,8-dihydroxy-3-(2'-acetyl-3',5'-dihydroxyphenyl)methylisocoumarin (6) related to the natural product feralolide (1a).     

C–H Arylation using acyl thiourea ligands: Applications in the synthesis of 3,6-diaryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles

Synthesis of a series of new 3,6-diaryl-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazoles(5a–o) was achieved by phophine free, C–H arylative cross-coupling of 6-aryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles(4a–o)with suitably substituted iodoanilines using 1-(2-naphthoyl)-3-(4-bromophenyl)thiourea as a ligand.The requisite triazolothiadiazoles(4a–o) were obtained by the condensation of 4-amino-1,2,4-triazole-3-thiol(3) with suitably substituted aromatic acids in the presence of phosphoryl chloride.