Band 70, Heft 11

Gadolinium borate fluoride oxide Gd 4 (BO 2 )O 5 F crystallises in space group Pmmn (no. 59, a = 1574.6(4), b = 381.42(7), c = 660.88(11) pm, 565 refl., 28 parameters, R 1 = 0.039, wR 2 = 0.128, twin refinement) and comprises linear BO 2 − anions between closely packed [GdO] layers formed by OGd 4 tetrahedra and terminated by oxygen and fluorine atoms. The crystal structure’s relationship with the NiAs type is illustrated. The Raman spectrum recorded on a single crystal of Gd 4 (BO 2 )O 5 F comprises a single peak at 1364 cm −1 assigned to the only Raman-active vibrational mode ν s of the linear triatomic O–B–O units besides very weak peaks at 805 and 2083 cm −1 (presumably the respective δ and ν as modes).

The compound 8-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-quinoline was prepared and found to hydrolyze rapidly in air; however, the expected product (quinolin-8-yl)boronic acid was not observed. Instead, the (quinolinium-8-yl)trihydroxyborate zwitterion or an anhydride were observed depending on the conditions of hydrolysis. The two products are related to one another in the degree of hydration, and the two forms could be interconverted. Both hydrolysis products were structurally characterized. Additionally, a commercial sample of ‘8-quinolylboronic acid’ was actually found to be the anhydride. The results call into question whether monomeric (quinolin-8-yl)boronic acid can actually be isolated in the neutral Lewis base-free form.

A series of novel substituted 6′-(4-chlorophenyl)-3,4′-bipyridine-3′-carbonitriles with incorporated pyrazole and/or triazole moieties have been synthesized using 2-(6′-(4-chlorophenyl)-3′-cyano-3,4′-bipyridin-2′-yloxy)acetohydrazide ( 3 ) as starting material. Also, the key intermediate 3 reacted with aromatic aldehydes and tosyl chloride to give the corresponding Schiff bases and tosyl hydrazide derivatives, respectively. The antimicrobial of these newly synthesized compounds was evaluated against Bacillus subtilis as Gram-positive bacteria and Trichoderma viride as a fungus; some of these compounds such as 5 , 6 , 7 , 8 , 10 , 12 , and 14 showed excellent activities as antimicrobial agents. Moreover, the cytotoxic activity of the most active compounds was assessed in vitro against human tumor liver cancer cell line (HEPG2); compounds 8 , 10 , 13a , and 14 showed potent activities relative to Doxorubicin which was used as a reference standard drug in this study.

The Michael addition of enaminoesters to coumarins ( 1 ) does not lead to the formation of simple adducts 3 but to the rearranged 4-aryl-2-pyridone 4a . Now, N -carbamoylation of the 6-amino-2-pyridone 4a with alkyl isocyanates and further transformation of the corresponding novel ureido-2-pyridone derivatives 6a–g into chromeno[3,4- c ]pyridines 5d , g and O -acetyl derivatives 7a–g are reported. All newly synthesized compounds were characterized by means of 1 H/ 13 C NMR, MS, IR spectra and elemental analysis. The structure of the ureide 6f and of the N -cyclohexyl- O -acetyl derivative 7g were additionally confirmed by crystal structure determinations. Acute toxicity after intraperitoneal administration, blood clotting time, analgesic activity and the effects on the hexobarbital sleeping time were tested on laboratory animals (compounds 4a , 6a , 6c , 6d and 6g ).

Ten 1,2,4,5-tetra-substituted imidazole derivatives have been synthesized with a 2-hydroxyethy substituent at the 1-nitrogen atom and potentially electron releasing hydroxy-, methoxy-, dimethylamino- or nitro substituents in various positions on the benzene ring located on the 2-carbon atom. The prototypical derivative with an unsubstituted phenyl ring at the 2-position is also reported. The compounds are obtained in excellent yields (average 86%) via a four-component cyclocondensation reaction of benzil, ethanolamine, and the appropriate aromatic carbaldehyde together with ammonium acetate. The reaction uses a novel ionic liquid catalyst, DEAHS (diethyl ammonium hydrogen sulfate), under solvent-free conditions and a green synthetic protocol. The key advantages of this process are high yield, shorter reaction times and ease of work-up. Furthermore, the products can be purified by a non-chromatographic method and the catalyst is re-usable. All of these newly synthesized compounds have been characterized from spectral data; the X-ray structures of three representative molecules are also detailed.

The ultrasound-assisted preparation of 2-(1 H -tetrazol-5-yl) acrylonitrile derivatives via a one-pot multi-component method is described successfully using ZrP 2 O 7 nanoparticles as a catalyst. Readily available tetrazoles can be transformed into the corresponding 1,5- and 2,5-disubstituted tetrazoles. 2,4′-Dibromoacetophenone gave the corresponding 2,5-disubstituted derivative as the only isomer. Synthesis of tetrazole derivatives with excellent yields in short times, a wide range of products under ultrasound irradiation, environmental benignity and a simple work-up procedure are some of the important features of this protocol.

Two minor taxane glycosides were isolated for the first time from the needles of Taxus canadensis . Their structures were characterized as 2 α ,5 α -diacetoxy-10 β -(6′- O -acetyl- β - d -glucopyranosyl)oxy-14 β -[(2′ R ,3′ S )-3′-hydroxy-2′-methylbutanoyl]oxytaxa-4(20),11-diene ( 1 ) and 2 α ,14 β -diacetoxy-10 β -( β - d -glucopyranosyl)oxytaxa-4(20),11-dien-5 β -ol ( 2 ) on the basis of 1D and 2D NMR data analysis and confirmed by high-resolution fast atom bombardment mass spectrometry.

Two new 24-nor-ursane-type triterpenoids, 2 α ,3 β ,19 α -trihydroxy-24-norurs-4(23),12-dien-28-oic acid ( 1 ) and 3 β -acetoxy-2 α ,19 α -dihydroxy-24-norurs-4(23),12-dien-28-oic acid ( 2 ), along with 15 known compounds were isolated from the methanol extract of the twigs of Mostuea hirsuta . While 2-hydroxymethylbenzamide ( 13 ) was isolated for the first time from the natural source, compounds 3–12 are reported here for the first time from the genus Mostuea . Their structures were elucidated by means of spectroscopic analyses including 1D- and 2D-NMR spectroscopy, high-resolution mass spectrometric data as well as comparison with data from the literature. Compounds 1 , 2 , 4–9 and 13 were tested against bacteria, fungi and plant pathogen oomycetes by the paper disk agar diffusion assay resulting in missing to low activities corresponding with minimum inhibitory concentrations (MICs) > 1 mg mL –1 . However, the respective compounds 1 , 2 , 8 , 9 and 13 exhibited moderate cytotoxic activity against the human Caucasian prostate adenocarcinoma cell line PC-3, with IC 50 10.6–16.5 μ m compared to the standard doxorubicin with IC 50 0.9 μ m .

New reactions of 4,15-diamino[2.2]paracyclophane ( 1 ) are described. When 1 is reacted with acetyl, benzoyl, or phthaloyl chloride, respectively, the amides 2 , 6 , 7 , and 9 are formed; the latter suffers loss of H 2 O to give the product 8 . Bromination of 2 yields the pseudo -geminally substituted derivative 3 exclusively; the formation of its expected regioisomer 4 is not observed. Heating of 2 with POCl 3 in ethanol furnishes the triply-bridged cyclophane 5 . Condensation of 1 with some selected carbonyl compounds (phthalaldehyde, formic acid, cyclohexane-1,3-dione, and terephthalaldehyde) provides the products 17 – 20 . Thiourea and isothiocyanate derivatives 21 and 22 were obtained on heating 1 in CS 2 . The structures of the products were assigned on the basis of their spectroscopic and analytical data. Rationalizations for the formation of 3 , 5 , 6 , and 17 are presented.