Chlorobenzene-driven palladium-catalysed lactonisation of benzoic acids

Herein, we developed a palladium-catalysed C-H cyclisation of benzoic acids in chlorobenzene without additional oxidants. The key to the success of these reactions is the use of chlorobenzene, which serves a dual role as a solvent and an oxidant, thus providing a simple and efficient method for synthesising phthalides.

Gold(I)-Catalyzed Heteroannulation of Salicylic Amides with Alkynes: Synthesis of 1,3-Benzoxazin-4-one Derivatives

Gold(I)-catalyzed heteroannulation affords the efficient and straightforward construction of heterocyclic compounds. Herein, we developed a gold(I)-catalyzed heteroannulation of salicylic amides with alkynes producing a broad range of 1,3-benzoxazin-4-ones. The utility of this protocol was highlighted by synthesizing variously substituted benzoxazinones containing quaternary carbon centers, showing a high functional group tolerance and excellent atom economy of the thus introduced reaction course.

Site-selective iodine atom transfer in fluorinated alkyl iodides via 1,5-hydrogen atom transfer

The direct and selective functionalization of inert C-H bonds via intramolecular hydrogen atom transfer (HAT) is an increasingly powerful tool in organic synthesis. Herein, we designed an efficient and facile iodine atom transfer in fluorinated alkyl iodides via 1,5-HAT. Our process enables site-selective iodination of unreactive C(sp³)-H bonds to afford di- and tri-fluorinated alkyl iodides in good yields. Furthermore, our process shows excellent atom economy and high functional group tolerance, including methyl, methoxy, chloro, cyano, and silyl moieties.

Nitrile Synthesis via Desulfonylative-Smiles Rearrangement

Herein, we designed a simple nitrile synthesis from N-[(2-nitrophenyl)sulfonyl]benzamides via base-promoted intramolecular nucleophilic aromatic substitution. The process features redox-neutral conditions as well as no requirement of toxic cyanide species and transition metals. Our process shows broad scope and various functional group compatibility, affording a variety of (hetero)aromatic nitriles in good to excellent yields.

Determination of Abiraterone and Its Metabolites in Human Serum by LC-ESI-TOF/MS Using Solid-phase Extraction

We developed and validated a liquid chromatography-electrospray ionization-time of flight/mass spectrometry method for the determination of abiraterone (Abi) and its metabolites (Δ⁴-Abi, 3-keto-5α-Abi, 3α-OH-5α-Abi and 3β-OH-5α-Abi) in human serum using Abi-d₄ as the internal standard. As a pretreatment procedure of serum samples, solid-phase extraction based on a silica-gel cartridge was used. The relative recovery of Abi and its metabolites was over the ranges of 84.5 - 109.2% at a concentration of 6.0 ng mL^-1 for Abi and 0.6 ng mL^-1 for its metabolites. The method was free from matrix effects. The calibration curve of Abi was linear over the range of 2.0 - 400 ng mL^-1 and those of its metabolites over the ranges 0.2 - 40 ng mL^-1. The results of the intra- and inter-day accuracy and precision data were within the FDA acceptance criteria. The optimized method was applied for the determination of Abi and its metabolites in human serum after oral administration of Abi acetate.

Retention and molecular-recognition mechanisms of molecularly imprinted polymers for warfarin derivatives and their application for the determination of warfarin in human serum

Monodisperse molecularly imprinted polymers (MIPs) for warfarin (WF), 4'-chlorowarfarin (CWF), 4'-bromowarfarin (BWF), 4'-nitrowarfarin (NWF) and 4'-methylwarfarin (MWF) (MIP_WF, MIP_CWF, MIP_BWF, MIP_NWF and MIP_MWF, respectively) were prepared using 4-vinylpyridine (4-VPY) and ethylene glycol dimethacrylate as a functional monomer and crosslinker, respectively, by multi-step swelling and polymerization. The retention and molecular-recognition properties of those MIPs were evaluated in HILIC, and reversed- and normal-phase modes. According to ¹H NMR studies, one-to-three complex formation of one WF or CWF molecule with three 4-VPY molecules occurred. Via computational approaches, the intermolecular interaction modes and energies between WF derivatives and 4-VPYs were evaluated by semi-empirical quantum chemistry methods and density functional theory calculations. Three major possible hydrogen bonding interaction modes were identified: the interactions between the 4-hydroxy group, α-proton (methylene C-H) and α-proton (methyl C-H) of the WF derivative and the nitrogen atoms of 4-VPYs. In HILIC and normal-phase modes, the interaction energies showed satisfactory correlations with the retention factors of the WF derivatives. In reversed-phase mode, the retention factors of the WF derivatives were described by the hydrophobicity and the acidity of the 4-hydroxy groups of the WF derivatives. These results demonstrate that three hydrogen bonding interactions in HILIC and normal-phase modes, and hydrogen bonding or ionic interactions and hydrophobic interactions in reversed-phase mode play important roles in the retention and molecular-recognition of the WF derivatives on MIPs. Furthermore, MIP_BWF was successfully applied to the determination of WF in human serum by column-switching LC with high accuracy, precision and selectivity and without template-leakage problems.

Palladium-catalyzed dehydrogenative C–H cyclization for isoindolinone synthesis

In this paper Pd-catalyzed intramolecular dehydrogenative C(sp³)–H amidation for the synthesis of isoindolinones is described. This method features the use of a Pd/C catalyst and the addition of a stoichiometric amount of oxidant is not necessary. A mechanistic study suggested the possible formation of H₂ gas during the reaction.

Pd-catalyzed intramolecular dehydrogenative C(sp³)–H amidation for the synthesis of isoindolinones was developed. Use of Pd/C as a catalyst enables the desired cyclization to proceed smoothly without adding any stoichiometric oxidants.

A solvent-dependent chirality-switchable thia-Michael addition to α,β-unsaturated carboxylic acids using a chiral multifunctional thiourea catalyst

An asymmetric thia-Michael addition of arylthiols to α,β-unsaturated carboxylic acids using a thiourea catalyst that bears arylboronic acid and tertiary amine moieties is reported.

An asymmetric thia-Michael addition of arylthiols to α,β-unsaturated carboxylic acids using a thiourea catalyst that bears arylboronic acid and tertiary amine moieties is reported. Both enantiomers of the Michael adducts can be obtained in high enantioselectivity and good yield merely by changing the solvent. The origin of the chirality switch in the products was examined in each solvent via spectroscopic analyses.

Retention and molecular-recognition mechanisms of molecularly imprinted polymers for promazine derivatives

Monodisperse molecularly imprinted polymers (MIPs) for promazine derivatives [promazine (PZ), methylpromazine (MPZ), chlorpromazine (CPZ) and bromopromazine (BPZ)], MIP_PZ, MIP_MPZ, MIP_CPZ and MIP_BPZ, were prepared using methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate as a crosslinker by multi-step swelling and polymerization. The retention and molecular-recognition properties of the obtained MIPs were evaluated using LC in hydrophilic interaction chromatography (HILIC) and reversed-phase modes. In computational approaches, intermolecular interaction modes and energies between PZ derivatives and MAAs were evaluated at the HF/6-311G(d,p) level. The interaction energies of PZ, MPZ, CPZ and BPZ with 4 equivalents of MAAs were calculated. The results indicated that the interaction of the aliphatic amine moiety of a PZ derivative with MAA gave almost similar interaction energies at the HF/6-311G(d,p) level, and that the interaction of the sulfur atom of a phenothiazine scaffold with MAA was also the case. The third interaction of the aromatic amine of a PZ derivative with MAA was in the order of MPZ > PZ > CPZ > BPZ presumably due to the change of basicity by the electron-donating or electron-withdrawing effect of a subsituent. Furthermore, the fourth attractive modes of CPZ and BPZ were suggested to be the interaction of their halogen atoms with MAA through both halogen bonding and hydrogen bonding, while PZ and MPZ were suggested to have the weak C-H ⋅⋅⋅ π interaction with MAA. In HILIC mode, the interaction energies at the HF method had good correlation with the retention factor of a PZ derivative on each MIP, indicating that in addition to the shape recognition, the attractive electrostatic interactions would be more responsible for its retention rather than the dispersion energies. Furthermore, in addition to the shape recognition, ionic and hydrophobic interactions, and halogen bonding and hydrogen bonding (the last interaction seems to be weak) seem to work for the retention and molecular-recognition of PZ derivatives on the MIPs in reversed-phase mode.

Inhibition of angiogenesis and tumor growth by a novel 1,4-naphthoquinone derivative

Hit, Lead & Candidate Discovery Antiangiogenesis therapy is a promising way for treatment of solid cancers, and many angiogenesis inhibitors that target vascular endothelial growth factor (VEGF) or its receptors have been developed. We explored novel antiangiogenic compounds other than anti-VEGF drugs by screening our synthetic compound library and found that 6-thiophen-3-yl-2-methoxy-1,4-naphthoquinone (6-TMNQ) had potential as a novel angiogenesis inhibitor. This paper describes the effects of 6-TMNQ on angiogenesis and tumor growth in vitro and in vivo. 6-TMNQ inhibited serum-, VEGF-, and basic fibroblast growth factor (bFGF)-stimulated proliferation of endothelial cells in a concentration-dependent manner, but had no effect on the proliferation of fibroblasts. VEGF-induced activation of VEGF receptor-2 in endothelial cells was not affected by the compound. 6-TMNQ markedly abrogated both migration and tube formation of endothelial cells. Orally administered 6-TMNQ inhibited angiogenesis in response to VEGF or bFGF in mice in a dose-dependent manner. Furthermore, when tumor-bearing mice were treated with 6-TMNQ, increase in tumor size was significantly prevented due to inhibition of angiogenesis in the tumor tissues. These results demonstrate that 6-TMNQ is an orally available compound that selectively inhibits endothelial cell proliferation and migration, and abrogates angiogenesis, resulting in the prevention of tumor growth. The mechanism of 6-TMNQ action is different from that of conventional anti-VEGF drugs.

Copper-Catalyzed Intramolecular C–H Amination: A New Entry to Substituted Xanthine Derivatives

Catalytic synthesis of xanthines was achieved in the presence of a copper catalyst. The process involves copper-catalyzed intramolecular C–H amination of benzamidines that possess a uracil moiety and produces variously substituted xanthines generally in good to high yields. This work introduces a new, facile approach to polysubstituted xanthine compounds.

Development of hemiacetal esterified levofloxacin to prevent chelation with metal-containing drugs

OBJECTIVES

To avoid the chelate formation between levofloxacin (LVFX) and aluminium hydroxide in gastrointestinal tract, an ethoxycarbonyl 1-ethyl hemiacetal ester of levofloxacin (LVFX-EHE) was synthesised as a prodrug.

METHODS

The effects of aluminium hydroxide on the bioavailability of LVFX following oral administration of LVFX-EHE were investigated in rats. Furthermore, the effects of aluminium hydroxide on small intestinal absorption of LVFX and LVFX-EHE when subjected to a hydrolysis experiment using in situ everted gut sac were investigated, and the minimal inhibitory concentrations (MICs) of LVFX and LVFX-EHE for various intestinal bacteria were measured.

KEY FINDINGS

When LVFX-EHE was co-administered with and without aluminium hydroxide, the AUC_{0-4 h} values of LVFX hydrolysed from LVFX-EHE were similar to that of LVFX alone. In everted gut sac experiments, LVFX-EHE was efficiently absorbed even in the presence of aluminium ions after 1 h of incubation, whereas the absorption of LVFX decreased significantly in the presence of aluminium ions. MIC values of LVFX-EHE were far higher than LVFX.

CONCLUSIONS

This study suggests the benefit of ethoxycarbonyl 1-ethyl hemiacetal esterification of the carboxyl group of new quinolone as a prodrug which is able to avoid chelate formation.

Two new dimeric coumarins isolated from Murraya exotica

Bismurrangatin and murramarin A, two new coumarins, were isolated from the vegetative branches of Murraya exotica. Murramarin A is a rare type of bicoumarin that connects two coumarin moieties by orthoester structure. The structures were elucidated based on spectroscopic methods, especially by 2D-NMR experiments.

Antiproliferative Activity of Rhinacanthus nasutus (L.) KURZ Extracts and the Active Moiety, Rhinacanthin C

Rhinacanthus nasutus (L.) Kurz (Acanthaceae) is a shrub widely distributed in South China and India. In this study, the antiproliferative activity of the ethanol extract of root and aqueous extract of leaves of R. nasutus, and the supposed active moiety rhinacanthin C was assessed in vitro using the human cervical carcinoma cell line HeLa, its MDR1-overexpressing subline Hvr100-6, human prostate carcinoma PC-3 cells and human bladder carcinoma T24 cells. Rhinacanthin C was chemically synthesized and its content in the R. nasutus extracts was determined by HPLC with a photodiode array detector. The antiproliferative activity of the R. nasutus extracts was also assessed in vivo using sarcoma 180-bearing mice. It was suggested that 1) the in vitro antiproliferative activity of rhinacanthin C was comparable with or slightly weaker than that of 5-FU, 2) rhinacanthin C showed antiproliferative activity for MDR1-overexpressing Hvr100-6 cells, similarly to parent HeLa cells, 3) the in vitro antiproliferative activity of the ethanol extract of root R. nasutus was due to rhinacanthin C, whereas that of the aqueous extract of leaves of R. nasutus was due to constituents other than rhinacanthin C, and 4) both of the R. nasutus extracts showed in vivo antiproliferative activity after oral administration once daily for 14 d.

Synthesis of beta-substituted alpha-amino acids with use of iridium-catalyzed asymmetric allylic substitution

The asymmetric synthesis of beta-substituted alpha-amino acids with use of iridium-catalyzed allylic substitution was described. The Ir-catalyzed allylic substitution of diphenylimino glycinate with allylic phosphates proceeded smoothly even at 0 degrees C and gave branch products with high enantioselectivity (up to 97% ee), when chiral bidentate phosphite bearing the 2-ethylthioethyl group was employed. In addition, both diastereomers of the branch products were synthesized stereoselectively by simply switching the base employed. These methods were also applied to the asymmetric synthesis of quaternary alpha-amino acids.

Synthetic study on CP-263,114 (phomoidride B) by SET-mediated fragmentation

Assembly of the highly functionalized carbocyclic core of CP-263,114 has been accomplished by using radical-mediated fragmentation with lithium naphthalenide as a key step.

Novel sparteine-mediated enantio-dichotomic formal synthesis of R-(-)- and S-(+)-curcuphenol

High and opposite enantiodiscriminations were observed between tertiary amides and secondary amides in the sparteine-mediated lateral metalation-allylation of 2-ethyl-m-toluamide derivatives (2a, 2e). The results described above have been applied for the formal synthesis of both enantiomers of curcuphenol. The brief mechanistic studies suggested that stereoinformation was introduced after the deprotonation step.

Association of Alport's syndrome with HLA-DR2 antigen in a group of unrelated patients

A few family studies have evaluated HLA antigens in Alport's syndrome; however, there are no large population studies. In the present report, we studied 40 unrelated white patients with Alport's syndrome seen at the Unit of Renal Transplantation, Faculty of Medicine of Ribeirão Preto, São Paulo, Brazil. HLA-A, -B, -DR and -DQ antigens were typed using a complement-dependent microlymphocytotoxicity assay. A control white population (N = 403) from the same geographical area was also typed for HLA antigens. Although the frequencies of HLA-A and -B antigens of patients were not statistically different from controls, the frequency of HLA-DR2 antigen observed in patients (65%) was significantly increased in relation to controls (26%; P < 0.001). The relative risk and etiologic fraction for HLA-DR2 antigen were 5.2 and 0.525, respectively. Although few immunological abnormalities have been shown in Alport's syndrome, in this report we emphasize the association of HLA molecules and Alport's syndrome. Besides the well-known inherited molecular defects encoded by type IV collagen genes in Alport's syndrome, the major histocompatibility alleles may be in linkage disequilibrium with these defective collagen genes.

Transforming growth factor beta (TGF beta) activity in urine of patients with glomerulonephritis

Several lines of experimental evidence have shown that transforming growth factor beta (TGF beta) may play major role in glomerular diseases, mediating the inflammatory response through glomerulosclerosis. In the present study we evaluated TGF beta activity in occasional urine samples from 7 normal individuals and from 15 patients (10 with focal glomerular sclerosis and 5 with membranous glomerulonephritis) using a CCL-64 mink lung cell growth inhibition assay. Urinary TGF beta activity (reported in relation to urine creatinine concentration, Ucr, mean +/- SD) was higher in patients with focal glomerular sclerosis (mean = 17.32 +/- 15.75/10 micrograms Ucr) and patients with membranous glomerulonephritis (mean = 17.78 +/- 11.53/10 micrograms Ucr) than in normal individuals (mean = 0.8 +/- 0.44/10 micrograms Ucr). We also observed that TGF beta activity in urine from patients with focal glomerular sclerosis correlated with their plasma creatinine levels (r = 0.85), suggesting that TGF beta activity may be correlated with other indices of disease progression. Our data suggest that measurement of urinary TGF beta activity could be a useful noninvasive procedure for the evaluation of renal TGF beta production, which may be useful to assess prognosis and to evaluate therapeutic efficacy in patients with renal disease.