Polyimides having pendant hydroxy and acetoxy groups. I. Synthesis of polyimides from pyromellitimide and bisepoxides

Polyimides having pendant hydroxy groups were prepared by addition of pyromellitimide with bisepoxides. Tertiary amines and quaternary ammonium halides were effective as a catalyst. The polyimides were soluble in dichloroacetic acid and had inherent viscosities in the range 0.16–0.19 dl/g. Thermogravimetric analysis showed that a rapid weight loss of the polymers occurred at about 400°C. The pendant hydroxy groups were easily acetylated by treating the polymers with a mixture of acetic anhydride and pyridine. The acetylated polyimides were soluble in dimethylformamide, dimethylacetamide, and dioxane and melted at 120–150°C.     

Synthesis,structure, and acylation of dihydroquinopimaric acid hydroxy derivatives

Reduction conditions of methyl dihydroquinopimarate with sodium borohydride and lithium aluminum hydride were established. As a result of the reduction 14β-hydroxy, 17α-hydroxy, 14β,17α-dihydroxy, and 14β,17α,21α-trihydroxy derivatives were obtained. The structure of methyl esters of 14β-acetoxy- and 17α-hydroxydihydroquinopimaric acid was established by XRD and NMR methods. Mono-, di-, and triacylates were obtained from the diterpene alcohols.     

Polyimides having pendant hydroxy and acetoxy groups. II. Polyimides derived from bisaminoalcohols

Polyamic acids were prepared from bisaminoalcohols and pyromellitic dianhydride. They were converted to polyimides having pendant hydroxy groups by heating them in toluene or xylene (η_inh = 0.22–0.34 dl/g). Treatment of these polyamic acids with a mixture of pyridine and acetic anhydride gave polyimides having pendant acetoxy groups (η_inh = 0.22–1.04 dl/g). These acetoxypolyimides were converted to hydroxypolyimides (η_inh = 0.20–0.81 dl/g) by an ester-exchange reaction. Furthermore, the hydroxypolyimides were easily acetylated to give acetoxypolyimides.     

Synthesis of derivatives of tetrahydrofuran and tetrahydropyran by intramolecular cyclization of unsaturated hydroxy compounds (review)

The literature data on reactions involving electrophilic heterocyclization of , -unsaturated alcohols, 2-allylphenols, oxiranes, aldehydes, and ketones are correlated. The factors that affects the reactivities of the unsaturated compounds (the structure of the substrate, the nature of the electrophile, and the nature of the solvent) in intramolecular cyclization are discussed. The problems of the regioselectivity of the addition and the stereochemistry of the resulting cyclization products are examined, and kinetic data are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1443–1462, November, 1982.     

Molecular compounds of dichloro-p-benzoquinone derivatives with hydroxy aromatic Schiff's bases

The molecular complexes of some hydroxy aromatic Schiff's bases with 2,3-dichloro-5,6-dicyano-p-benzoquinone and chloranilic acid are prepared and investigated using electronic absorption, i.r. and ¹H-NMR spectroscopy. Molecular compounds with the former reagent are formed through charge transfer while those with chloranilic acid are formed through proton and electron transfer.     

Synthesis and cytotoxic activity of isocembrol and its hydroxy derivatives

Russian Chemical Bulletin - The synthesis of 2- and 3-hydroxy derivatives of isocembrol was accomplished by the epoxidation of isocembrol with tert-butyl hydroperoxide in the presence of a...     

Synthesis and antioxidant activity of new hydroxy derivatives of chalcones

New hydroxy derivatives of chalcones obtained via a condensation of 3-acetyl-2H-chromen-2-one with 2,4-dihydroxy- and 4-hydroxy-benzaldehydes and via an aldol crotonic condensation of methyl N-(4-acetylphenyl)carbamate with 4-hydroxy-3,5-di(tert-butyl)benzaldehyde have been isolated and characterized. A wide range of promising biological activity of the synthesized compounds, including the radical scavenging and antioxidant ones, was predicted by the in silico method. The anti- and pro-oxidant activities in model systems of peroxidation of cis-9-octadecenoic (oleic) acid and lipids from the liver homogenate of tilapia were estimated in vitro. The presence of sterically hindered hydroxy groups and a chromene moiety provides the prolonged antioxidant activity of new hydroxy derivatives of chalcones.

     

Synthesis of hydroxy derivatives of 2,5-diaryl-1,3,4-oxadiazoles

A method for the synthesis of hydroxy derivatives of 2, 5-diaryl-1,3,4-oxadiazoles has been developed which consists in the preparation of acetoxy derivatives of oxadiazole with their subsequent saponification by means of an alcoholic solution of sodium hydroxide.     

Synthesis,spectroscopic and antibacterial investigations of new hydroxy ethers and heterocyclic coumarin derivatives

The reactions between oligoethylene glycol diglycidyl ethers 2a‐c with both 7‐hydroxy‐4‐methyl‐2H‐chromen‐2‐one and 4‐hydroxy‐2H‐chromen‐2‐one lead to new hydroxy ethers 3 and 4 containing coumarin moieties in good yield. The synthesis of 3‐(3‐(dimethylamino)acryloyl)‐4‐hydroxy‐2H‐chromen‐2‐one 5 and new heterocyclic compounds 4‐hydroxy‐3‐(1H‐pyrazol‐3‐yl)‐2H‐chromen‐2‐one 6a , 4‐hydroxy‐3‐(1‐phenylpyrazol‐3‐yl)‐2H‐chromen‐2‐one 6b and 4‐hydroxy‐3‐(isoxazol‐3‐yl)‐2H‐chromen‐2‐one 6c is also described. All compounds were characterized by ¹H NMR, ¹³C{¹H} NMR, 2D‐¹H‐¹³C HMBC, 2D‐¹H NOESY NMR, IR, and MS spectroscopy. Additionally, the antibacterial activity of the new products containing coumarin moiety was evaluated. This activity is clearly dependent on the chemical structure of compounds.     

Synthesis of zinc,cadmium, tin,and silicon derivatives of cubane

Metallocubanes are shown to be available by a transmetalation procedure in which amide-activated cubanes are treated with LiTMP and a metal chloride. They are excellent precursors for new subsituted cubanes.     

Synthesis of bridgehead hydroxy bicyclo[2.2.2]octane derivatives

Two independent synthetic routes, starting from 1,3-cyclohexadione, toward the 4-hydroxy bicyclo[2.2.2]octane-2,6-dione derivative 3 are described.     

含硅二烃基锡(Ⅳ)邻菲咯啉配合物的合成及结构表征

1980年,Crowe等人首次报道了六配位有机锡(Ⅳ)配合物R2SnX2L2(R=烷基或苯基;X=F,C l,Br,I或NCS;L为含O或N的有机配体)对P388淋巴白血病细胞有抑制活性[1]。以后人们合成许多二烃基锡配合物,并对基作了广泛的研究[2,3]。结果表明,二烃基锡化合物的抗肿瘤活性主要取决于烃基,混合二烃基锡化合物毒性较高,使它们的应用受到一定的限制。在药物分子中,某个碳原子被硅取代,称为硅药(Sila-drug),其特点是能降低毒性,有时也能提高药效[6]。因此,开展对含硅有机锡化合物进行研究,对于探讨分子中引入硅原子后对有机锡化合物性质的影响有一定的…