Synthesis of bioreductive esters from fungal compounds

Four new bioreductive esters (7-10) have been synthesized. Their structures composed of trimethyl lock containing quinone propionic acid with an ester linkage to the fungal cytotoxic compounds; preussomerin G (1), preussomerin I (2), phaseolinone (3) and phomenone (4). The synthesized esters are aimed to act via reductive activation specifically at the cancer cells, resulting from hypoxia and overexpression of reductases. Hence, the toxicity will be lessened during distribution across the normal cells. The anticancer activity was determined in cancer cell lines with reported reductase i.e., BC-1 cells and NCI-H187 as well as in non-reductase containing cancer cells; KB cells. When considering each cell lines, result showed that structure modification giving to 7-10 led to less cytotoxicity than their parent compounds (1-4). Both 7 and 8 were strongly cytotoxic (IC50 < or = 5 microg/ml) to NCI-H187, whereas 9 and 10 were moderately cytotoxic (IC50 = 6-10 microg/ml) to BC-1 cells. Additional study of stability of represented phenolic ester (8) and an alcoholic ester (9) were performed. Result illustrated that both 8 and 9 were stable in the presence of esterase. Therefore, the cytotoxicity of the synthesized compounds (8-10) might be due to partial bioreductive activation in the cancer cells.     

Preparation of 2-aryl and 2-aryloxymethyl imidazo[1,2-a]pyridines and related compounds

A series of substituted 2-aryl imidazo[1,2-a]pyridines has been prepared in which a variety of substituents are introduced on the 4′-position of the phenyl ring and on the 3, 5 , 6 or 7 position of the heterocyclic ring. Most examples have acetamido, bromo, cyano, or formyl substituents at the 4′-position. Analogous imidazo-[2,1-b]fhiazoles and imidazo[1,2-a]pyrimidines have also been prepared. Another series of compounds consisting of 4′-formylphenoxymethyl derivatives of imidazole, the three positional isomers of pyridine, thiazole, benzimidazole and ring-substituted imidazo[1,2-a]pyridines has been prepared. 2-(4′-Formylphenylethenyl) derivatives of imidazole and imidazo[1,2-a]pyridine were also prepared.     

Preparation of unsymmetrical dialkyl acetylenedicarboxylates and related esters by enzymatic transesterification

An unexpected highly selective mono-transesterification of symmetrical acetylenedicarboxylates with various alcohols occurred in the presence of Candida rugosa lipase. This reaction allows an efficient preparation of unsymmetrical acetylenedicarboxylates and related α,β-acetylenic esters.     

Fluoroacrylic esters and related monomers: Preparation and use as synthons

Preparations of acrylic compounds substituted by fluorine atoms or trifluoromethyl groups at the a or β positions are reviewed. Their use in Michael additions, annelation reactions and Diels-Alder condensations leads to more complex molecules, such as fluorinated analogues of natural products.     

Preparation and some reactions of organogermylmercuryplatinum complexes and related compounds

A single-crystal X-ray diffraction study of tetracarbonyl-ferra-3-cyclopentene-2,5-dione has been made. Formally the compound can be derived from maleic anhydride by substitution of the bridging oxygen by Fe(CO)₄. Accordingly the bonding character is similar to that of maleic anhydride. The ironcarbon distances in the ring indicate partial double bonds. The octahedrally coordinated iron atom is linked to four terminal carbon monoxide ligands, with a longer bond distance to the equatorial than to the axial ones (FeC_ax 1.809 Å, FeC_eq 1.854 Å). The axial CO groups are strongly inclined towards the ring (C_axFeC_ax 164°). The latter effect is explained by electronic repulsion of the CO groups.IR, ¹H NMR, and ¹³C NMR data are reported. Crystal data: space groupPnama:α  12.708(10),b  10.058(7),c  7.527(5) Å;Z  4. With 625 reflections [F_o > 3o(F_o)] the structure has been refined anisotropically (hydrogen isotropically) to R0.022.     

Pyrroles and related compounds—XXXIV : Acrylic esters in the porphyrin series

Treatment of imidazolylporphyrins (12) with sodium borohydride in methanol affords high yields of the corresponding hydroxymethylporphyrins (14) which can be oxidised with chromium trioxide in pyridine to give high yields of formylporphyrins (11). When heated with methyl hydrogen malonate in pyridine, good yields of porphyrin trans-acrylic esters (15) are produced; a milder method involving reaction of the formylporphyrin (11a) with a phosphonium ylid (20) or better, a phosphonate ester (21), gives good yields of the porphyrin trans-acrylic ester (16a).Porphyrin β-keto-esters (e.g. 8b) are reduced with sodium borohydride in methanol, to give the 6-hydroxypropionate ester (17b); prolonged treatment with borohydride results in over-reduction at the 7-propionate side-chain. The hydroxypropionate porphyrin (17b) is readily dehydrated to give a high yield of the porphyrin trans-acrylic ester (15b). Methods for the magnesiation and preparation of β-keto-ester and trans-acrylic ester porphyrin 7-propionic acids are described; hydrolysis of porphyrin β-keto-esters (e.g. 8b) can be controlled such that only the propionic function is hydrolysed. However, prolonged alkaline hydrolysis and re-esterification furnishes a mixture of 2-vinylrhodoporphyrin-XV dimethyl ester (9b) and the 2-vinyl-6-acetylporphyrin (18b). The latter porphyrin can also be prepared by treatment of the acid chloride (10b) from 2-vinylrhodoporphyrin-7-methyl ester with sodio di-t-butyl malonate, followed by treatment with trifluoroacetic acid.     

13C Nuclear magnetic resonance spectroscopy of biliverdin IX dimethyl esters and related compounds

The ¹³C NMR spectra of differently substituted or conformationally restrained biliverdins have been recorded. Certain characteristics are found for these tetrapyrrolic systems, i.e. the chemical shifts of the methine bridge carbons, the vinyl groups and the bis-lactam form. This study, in conjunction with other spectroscopic data, may be used to assign the structures of biliverdins IX αβγλ, phorcabilin, isophorcabilin and neobiliverdin IXλ.     

Preparation of trialkylborines by the action of organometallic compounds on metaboric esters

Summary Metaboric esters were alkylated to trialkylborines with trialkylaluminums, dialkylzincs, and also alkylmagnesium halides.     

Derivatives of 2-oxo-3(2H)-benzothiazolineacetonitrile and related compounds. II. Synthesis of 2-oxo-alkyl esters of 3(2H)-benzothiazolineacetimidic acids and related products

The reaction of the appropriate 2-benzothiazolinone or 2-benzoxazolinone under basic conditions with (1) 2-chloropropionitrile, (2) acrylonitrile, (3) 4-chlorobutyronitrile or (4) chloroacetonitrile afforded the nitriles 1–8 . The reaction of various nitriles with alcoholic-hydrogen chloride solutions at low temperatures afforded the hydrogen chloride salts of the imino-ester which upon neutralization with potassium carbonate yielded the titled compounds.     

Preparation and properties of nitrogen-substituted thiosulfinyl compounds and related new heterocycles

The reaction of dilithiated N,N′-dimethyl-1,2-diphenylethylenediamine with disulfur dichloride (S₂Cl₂) gave a thiosulfinyl compound (R₂N)₂SS, 2,5-dimethyl-3,4-diphenyl-1,2,5-thiadiazolidine 1-sulfide, whereas the treatment of dilithiated N,N′-bis(p-toluenesulfonyl)-1,2-diphenylethylenediamine with S₂Cl₂ furnished a new heterocycle, 3,6-bis(p-toluenesulfonyl)-4,5-diphenyl-4H,5H-1,2,3,6-dithiadiazine.     

Structural organization of ethyl esters based on hexafluoropropene oxide oligomers: Inverse gas chromatography study

Samples of ethyl esters of perfluorinated acids based on hexafluoropropene oxide oligomers with molecular masses of 2000, 3100, and 4500 are used as stationary phases, and their interactions with low-molecular-mass compounds (sorbates) of different natures are studied by inverse gas chromatography. The linear dependence of the specific retention volumes for alkanes, cyclohexane, aromatic hydrocarbons, tetrachloromethane, and trifluorotrichloroethane (CFC-113) on inverse molecular masses of the oligomer samples is ascribed to the quasi-biphasic structure of the liquid oligomers. The experimental dependences of specific retention volumes on inverse molecular masses of oligomer samples make it possible to estimate the main thermodynamic characteristics of sorbate interaction with individual quasi-phases and their solubility parameters directly related to the cohesion-energy density.     

The use of hexafluoropropene oxide in substitutive fluorination of SbV and BiV oxygen-containing compounds

Reactions of hexafluoropropene oxide with Sb^V and Bi^V oxygen-containing compounds were studied. The E=O (E−O) groups were found to be transformed into the EF₂ (E−F) (E=Sb or Bi) groups. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1652–1653, August, 1998.     

Preparation of complex bridged bicyclic ring systems from 3,3-diacetoxy-2-phenylsulfonylpropene and beta-keto esters

The reaction of beta-keto esters with 3,3-diacetoxy-2-phenylsulfonylpropene affords bicyclic keto esters in good yields.     

Preparation of alkyl esters of benzimidazol-2-ylcarbamic acid

Alkyl esters of benzimidazol-2-ylcarbamic acid have been synthesized by the saponification of cyanamidobenzimidazole with various alcohols in the presence of concentrated hydrochloric acid.Institute of The Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 704–706, September–October, 1979.     

Preparation of alkyl esters of benzimidazol-2-ylcarbamic acid

Alkyl esters of benzimidazol-2-ylcarbamic acid have been synthesized by the saponification of cyanamidobenzimidazole with various alcohols in the presence of concentrated hydrochloric acid.     

Acid dissociation of 2-mercaptohistamine and its related compounds

The acid dissociation constants of 2-mercaptohistamine hydrochloride (2-MH) and its related compounds ergothioneine (Erg), 2-mercaptoimidazole (MI), N-methyl-2-mercaptoimidazole (MMI) and histamine dihydrochloride were determined by potentiometry at 15 degrees , 25 degrees and 35 degrees and mu = 0.1 (NaClO(4)). The values of DeltaH and DeltaS for the ionization equilibria were calculated. The magnitude of DeltaH (9.5 kcal/mole) for pk(a1) of 2-MH is similar to the value DeltaH = 9-10 kcal/mole found for the ionization of a number of amino groups. The value DeltaH = 7.4 kcal/mole for pk(a2) of 2-MH is similar to the values for the ionization of a variety of thiols (DeltaH = 5-7 kcal/mole). Such values were not obtained for Erg, MI and MMI, which suggests that 2-MH exists mainly in the thiol form, whereas Erg, MI and MMI are in the thione form.     

Polymers derived from 2,5-diamino-p-benzoquinone-diimide and related compounds

A number of new polymeric materials have been prepared by the self-condensation of 2,5-diamino-p-benzoquinonediimide and by its condensation with 2,5-diamino-p-benzoquinone, 2,5-dihydroxy-p-benzoquinone, and 2,5-dichloro-p-benzoquinone. Ladder polymers were expected, but in every case polymers with some open rings were obtained. 2,5-Diaminohydroquinone was condensed with 2,5-diamino-p-benzoquinonediimide and with 2,5-diamino-p-benzoquinone to produce heat stable polymers but the expected ladder structures were not obtained. Thermogravimetric analyses of the polymers in nitrogen all showed a weight loss at 100–150°C of 3–14% which was presumably due to loss of either chemically combined or absorbed water on the polymer and then only a 5% weight loss up to about 600°C with a final weight loss of 19% at 900°C.     

Preparation of 5-substituted 3-aminofuran-2-carboxylate esters

[reaction: see text] An efficient method for the preparation of 3-aminofuran-2-carboxylate esters has been developed. This method is based on the reaction of an alpha-cyanoketone with ethyl glyoxylate under Mitsunobu conditions to produce a vinyl ether in good yield. Subsequent treatment of the vinyl ether with sodium hydride afforded the 3-aminofuran. It was also found that a one-pot procedure using the Mitsunobu reaction followed by cyclization afforded the 3-aminofuran in comparable yield. Currently, this method is limited to the synthesis of 5-alkyl-, 5-aryl-, and 4,5-fused bicyclic furans.     

Synthesis of 2-amino-2-deoxo-5-deazaflavins and related compounds

10-Alkyl-2-amino-2-deoxo-5-deazaflavins were prepared by the condensation of 2-amino-6-chloro-5-formylpyrimidin-4(3H)-one with the corresponding N-alkylanilines. 2-Amino-10-p-tolyl-2-deoxo-5-deazaflavin was prepared by the condensation of 2-amino-6-p-toluidinopyrimidin-4(3H)-one with o-chlorobenzaldehyde. Some reactivities of 2-aminopyrimidin-4(3H)-ones are described.     

Preparation of quinolines from resin-bound esters using titanium reagents

ortho-Amino homobenzylic thioacetals are prepared from ortho-nitrobenzaldehydes via homologation using an alpha-methoxy Wittig reagent. Titanium reagents are generated from the 1,3-dithianes using a low valent titanium reagent and are then used to alkylidenate resin-bound esters. An N-silylated Boc group protects the ortho-amino functionality. Traceless SPS of quinolines is completed by treating the resulting resin-bound enol ethers with TFA and then oxidizing with manganese dioxide to give 2-substituted quinolines in high purity without the need for chromatography.