Syntheses of 2- or 6-Substituted Chromones and Chromone Ring-opening Reaction in Polyphosphoric Acid

In an attempt to find new antitumor agents,a novel class of chromone compounds with a benzimidazole or a benzoxazole ring in positions 2 or 6 were synthesized via condensation in polyphosphoric acid(PPA) by using chromone acids as the starting materials. During the preparation process,it was found that PPA could cleave the chromone ring to produce a ring-opening compound(6). The molar ratio of the chromone compound(5) to the ring-opening compound(6) varied with the change of reaction temperature and time. Based on MTT protocol,the antitumor activity of each of the compounds obtained was evaluated against three human cancer cell lines: KB(oral epidermal),A2780(ovary) and Bel7402(liver). The IC_ 50 varied from 54.7 μmol/L to more than 180 μmol/L.

The Structure Development of Cellulose Dissolved in the Phosphoric Acid/Polyphosphoric Acid Solvent

Cellulose,being as the most abundant nature polymer material and the most promising oil substitute,attracts more and more interests.A new cellulose dissolution system,phosphoric acid(PA)/polyphosphoric acid(PPA) solvent,was investigated in this study.It had been found that a larger cellulose solid content could be dissolved quickly in a hypothermic situation.By evaluating the stability of regenerated cellulose film and the formation of anisotropic solution,the dissolution behavior of cellulose was investigated.Wide-angle X-ray diffraction(WAXD) and Fourier transform infrared spectroscopy(FT-IR) were employed to characterize the crystalline structure and morphology of regenerated cellulose.The measurement results revealed a transition from cellulose-Ⅰ of raw cellulose to cellulose-Ⅱ of regenerated cellulose and a decrease of crystallinity of cellulose after dissolved.This was attributed to the interaction between cellulose and acid solvent,which leaded to the breakage of cellulose intra-and inter-molecule hydrogen bonds and the conformation change of cellulose C6-OH.Moreover,the formation process of cellulose liquid crystal solution was illustrated by polarized light microscope(PLM).That may be induced by the rearranging movement of the cellulose macromolecular chains.

Cyclization of 2-methoxy-6-(substituted benzyloxy)acetophenone hydrazones in the presence of polyphosphoric acid(PPA)

Cyclization of 2-methoxy-6-benzyloxy acetophenone hydrazone gave 3-methyl-4-meth- oxy indazole and 3-methyl-4-methoxy-7-benzyl indazole in the presence of polyphosphoric acid (PPA).The hydrazone was probably converted to 2-hydroxy-6-methoxy acetophenone hydra- zone and 2-hydroxy-3-benzyl-6-methoxy acetophenone hydrazone followed by cyclization to the corresponding indazoles in acidic conditions.Cyelization of 2-methoxy-6-(halo or alkyl or aryl benzyloxy)acetophenone hydrazones gave similar products.Cyclization of 2-methoxy-6- (p-nitrobenzyloxy)acetophenone hydrazone gave 2-(p-nitrophenyl)-3-methyl-4-methoxy benzo- furan and 3-methyl-4-methoxy indazole while 2-methoxy-6-(m-nitrobenzyloxy)acetophenone hydrazone gave 3-methyl-4-methoxy indazole,3-methyl-4-methoxy-7-(m-nitrophenyl)indazole and 3-methyl-4-(m-nitrobenzyloxy)indazole.

Synthesis of 6-chloro and 6-fluoro-4-hydroxyl-2-quinolone and their azo disperse dyes

In this study,6-chloro-4-hydroxy-2-quinolone and 6-flouro-4-hydroxy-2-quinolone were synthesized from corresponding dianilides.These compounds were coupled with some diazotized aromatic amines to give the corresponding azo disperse dyes.The structures of the quinolone derivatives and new azo dyes were confirmed by UV-vis,FT-IR,;H NMR and elemental analysis.

Synthesis and Cyclization of 8-Formyl-2-（phenoxymethyl）- quinoline-3-carboxylic Acids

A facile synthesis of a series of new quinoline-8-carbaldehyde compounds, namely 8-formyl-2- （phenoxymethyl）quinoline-3-carboxylic acids （4a--4h） and 13-oxo-6,13-dihydro[1]benzoxepino[3,4-b]quinoline- 8-carbaldehyde （5a--5g） is described, involving the one-pot synthesis reaction of ethyl 2-（chloromethyl）-8- formylquinoline-3-carboxylate （3） with substituted phenols followed by the intramolecular cyclization reaction via the treatment with polyphosphoric acid （PPA）. Quinoline-8-carbaldehydes 4a--4h and 5a--5g are novel and their structures were supported by IR, IH NMR, 13C NMR, MS and elemental analysis.

PPA-SiO_2 catalyzed efficient synthesis of polyhydroquinoline derivatives through Hantzsch multicomponent condensation under solvent-free conditions

Silica gel-supported polyphosphoric acid （PPA-SiO2） was found to be an efficient catalyst for the one-pot four-component Hantzsch condensation reaction of aryl aldehydes, dimedone, ethyl acetoacetate and ammonium acetate to afford the corresponding polyhydroquinoline derivatives in high yields. The main advantages of the present approach are short reaction times, clean reaction profiles, simple experimental and workup procedures.