Band 17, Heft 1-2

No abstract available

The C9′-C15′ fragment of enacyloxins, a series of antibiotics isolated from Frateuria sp. W-315, was synthesized from diethyl d -tartrate.

The C16′-C23′ fragments of enacyloxins, a series of antibiotics isolated from Frateuria sp. W-315, were synthesized from d -arabinose.

The synthesis of six new benzyloxycyanoboronic esters: 2-benzyloxy-6-cyanophenyl-4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane ( 4a ), 4-benzyloxy-2-cyanophenyl-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane ( 4b ), 4-benzyloxy-3-cyanophenyl-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane ( 8a ), 2-benzyloxy-5-cyanophenyl-4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane ( 8b ), 3-benzyloxy-4-cyanophenyl-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane ( 12a) , and 2-benzyloxy-5-cyanophenyl-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane ( 12b ) is reported.

Reaction of 4-piperidone with alkyl bromides gave the corresponding N -alkyl-4-piperidones, and treatment of these with hydrazoic acid resulted in the Schmidt reaction to give the corresponding N 1 -alkyl-1,4-diazepin-5-ones in good overall yields.

Efficient synthetic routes to the title compounds 2-amino-5-chloro-3-pyridinecarboxaldehyde (1a) and 5-amino-2-chloro-4-pyridinecarboxaldehyde (1b) are reported. Both compounds are important substrates in the synthesis of naphthyridine derivatives.

The condensation reaction of 2-aminoprop-1-ene-1,1,3-tricarbonitrile ( 1 ) with 2-acetyl-furan ( 2 ) afforded 2-amino-4-(furan-2-yl)penta-1,3-diene-1,1,3-tricarbonitrile ( 3 ). The latter compound underwent a series of heterocyclization reactions to give quinoline, furan, pyrazole and thiophene derivatives. The antitumor evaluation of the newly synthesized products against three cancer cell lines, namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) were recorded. Three of the synthesized compounds, namely 4 , 5d and 12 showed high inhibitory effects.

A series of 1,3,5-triazine derivatives that contain aniline, 4-hydroxy- N -methylquinolone and different piperazine and piperidine moieties as substituents on the carbon atoms of the triazine ring has been synthesized by a simple and efficient synthetic protocol. Comparative studies were performed on the compounds, which were synthesized with conventional and microwave heating methods. The microwave method was observed to be more beneficial as it provides an increase in yield and 90%–95% reduction time. The antimicrobial activity of the compounds was tested against seven bacteria ( Staphylococcus aureus , Bacillus cereus , Escherichia coli , Pseudomonas aeruginosa , Klebsiella pneumonia , Salmonella typhi , Proteus vulgaris ) and two fungi ( Aspergillus niger , Candida albicans ). The results indicate that some of the novel s -triazines have noteworthy activity in MIC and agar diffusion tests.

The reaction of 4-amino-5-bromo-2-chloro-6-methylpyrimidine ( 1 ) with carbon disulfide in the presence of KOH in DMF quantitatively gave 5-chloro-7-methylthiazolo[4,5- d ] pyrimidine-2 (3 H )-thione ( 2 ) which was then alkylated at the sulfur atom with various alkyl halides in the presence of Et 3 N in acetonitrile to give alkylthio derivatives 3 . The substitution of the chlorine atom in 3 with morpholine was also investigated. The synthesized compounds were subjected to antibacterial evaluations.

New derivatives of pyrimido[4,5- e ][1,3,4]oxadiazine were prepared and their antibacterial evaluations were performed on four different Gram-negative and Gram-positive bacteria.

The title compound, (R) -(-)- N -dichloroacetyl-3-ethyl-1-oxa-4-aza-spiro-4.5-decane 3 was synthesized by a sequential procedure involving condensation of (R) -2-amino-butanol with cyclohexanone and acylation of the resultant intermediate spiro compound with dichloroacetyl chloride. The X-ray structure determination confirmed the structure and the product was further characterized by IR, 1 H-NMR, and 13 C-NMR spectroscopy, mass spectrometry, and elemental analysis.

A facile synthetic route was developed to N -dichloroacetyl-2,3-dihydrobenzoxazole derivatives 3 by cycloaddition of 2-amino-phenol ( 1 ) with dichloromethane and acylation of the resultant intermediate 2,3-dihydrobenzoxazole 2 with dichloroacetyl chloride. The structures of the compounds were characterized by IR, 1 H NMR, and 13 C NMR spectroscopy and elemental analysis. The preliminary biological tests showed that products 3 could protect maize against injury caused by acetochlor to some extent.

Five novel acetyl derivatives of 2-pyrazoline 6–10 were synthesized by the reaction of chalcones 1–5 with hydrazine hydrate and chloroacetic acid in ethanol. The products were purified by silica gel chromatography and characterized by ESI-MS, FT-IR, UV, 1 H NMR, 13 C NMR and microanalysis.

The reaction of arylisothiocyanate derivatives with sodium methyl cyanoacetate in tetrahydrofuran gave the corresponding thioxo-propanoates, the reaction of which with hydroxylamine in ethanol and ammonium acetate under reflux conditions provided a synthetically useful method for the synthesis of methyl 5-amino-3-arylaminoisoxazole-4-carboxylates in good yields.

1,4-Bis(6-aryl-1,2,4-triazolo[3,4- b ]-[1,3,4]thiadiazol-3-yl)­benzenes ( 3 ) were synthesized in high yields by reaction of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)benzene ( 1 ) with carboxylic acids 2 in the presence of POCl 3 and tetrabutylammonium iodide as catalyst. The MTT assay indicated that compounds 3a–i possess inhibitory activity against the proliferation of HepG-2 (liver cancer), A549-1 (lung cancer) and 231-2 (breast cancer).

A series of 1-(substituted phenyl)-3-[α-(alkyloxyimino)-benzylidene]pyrrolidine-2,4-dione derivatives as a mixture of two geometrical isomers of Z -configuration and E -configu­ration were synthesized by the reaction of the corresponding α-hydroxybenzylidene analogs with alkyloxyamine hydrochlorides. The target compounds were confirmed by IR, 1 H NMR, MS and elemental analysis. The title compounds exhibit inhibitory activity against Echinochloa crusgalli and Brassica campestris .

A novel, acid catalyzed multicomponent one-pot synthesis of 2-aryl-1 H -phenanthro[9,10- d ]imidazole compounds derived from aromatic aldehydes, 9,10-phenanthrenequinone and ammonium acetate under ultrasonic irradiation is reported. A wide range of aromatic aldehydes readily undergo condensation with 9,10-phenanthrenequinone and ammonium acetate under optimized conditions to afford the desired imidazoles of good purity in excellent yields.

Bis-bromine-1,4-diazabicyclo[2.2.2]octane (Br 2 -DABCO) is an efficient, readily available, and reusable catalyst for the synthesis of 14-aryl-14 H -dibenzo[ a,j ]xanthenes 3 by condensation of β-naphthol 2 and aldehydes 1 . This reaction under solvent-free conditions is very simple, affording good to excellent yields of products.

A new taxane peroxide, 4α,10β,13α-acetoxy-2α-benzoyloxy-7β,9α-epidioxy-5β,20-epoxytax-11-en-1β-ol ( 1 ), was isolated and characterized for the first time in rooted cuttings of the Canadian yew, Taxus canadensis .