Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

A series of mononuclear metal complexes of Co(III), Ni(II) and Cu(II) with 2‐(2,4‐dichlorobenzamido)‐N′‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide ( LH ₃ ) have been synthesized and characterized using various physico‐chemical, spectroscopic and single crystal X‐ray diffraction techniques. Structural studies of [Co( LH )( LH ₂ )]·H₂O ( 4 ) revealed the presence of both amido and imidol tautomeric forms of LH ₃ , resulting in a distorted octahedral geometry around the Co(III) ion. [Ni( LH )(H₂O)]·H₂O ( 5 ) and [Cu( LH )(H₂O)]·H₂O ( 6 ) are isomorphous structures and crystallize in the monoclinic P2₁/c space group. The crystal structures of 4 , 5 and 6 are stabilized by hydrogen bonds formed by the enclathrated water molecules, C‐H···π and π···π interactions. Complexes along with the ligand ( LH ₃ ) were screened for their in vivo anti‐inflammatory activity (carrageenan‐induced rat paw edema method) and in vitro antioxidant activity (DPPH free radical scavenging assay). Metal complexes have shown significant anti‐inflammatory and antioxidant potential.     

Design,Synthesis and Biological Evaluation of Novel N‐(4‐([2,2′:5′,2′′‐Terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) Benzamide Derivatives

On the basis of the principle of combination of active groups, a series of novel N‐(4‐([2,2′:5′,2′′‐terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) benzamide derivatives were designed, synthesized and systematically evaluated for their antiviral activity against tobacco mosaic virus (TMV). The bioassay results showed that most of these compounds displayed good anti‐TMV activity, and some of them exhibited higher antiviral activity than commercial Ningnanmycin. Especially, compound 8e with excellent anti‐TMV activity (inactivation activity, 92.3%/500 µg·mL^?1; curative activity, 85.7%/500 µg·mL^?1 and protection activity, 64.7%/500 µg·mL^?1) emerged as a potential inhibitor of plant virus TMV. Quantitative structure‐activity relationship studies proved that the van der Waals volume (V) and electronic parameter (∑(∑σ_o+σ_p) and ∑σ_m) for the substituent R¹ were very important for antiviral activities in this class of compounds.     

Synthesis,crystal structures and anti‐inflammatory activity of four 3,5‐bis(arylidene)‐N‐benzenesulfonyl‐4‐piperidone derivatives

3,5‐Bis(arylidene)‐4‐piperidone (BAP) derivatives display good antitumour and anti‐inflammatory activities because of their double α,β‐unsaturated ketone structural characteristics. If N‐benzenesulfonyl substituents are introduced into BAPs, the configuration of the BAPs would change significantly and their anti‐inflammatory activities should improve. Four N‐benzenesulfonyl BAPs, namely (3E,5E)‐1‐(4‐methylbenzenesulfonyl)‐3,5‐bis[4‐(trifluoromethyl)benzylidene]piperidin‐4‐one dichloromethane monosolvate, C₂₈H₂₁F₆NO₃S·CH₂Cl₂, ( 4 ), (3E,5E)‐1‐(4‐fluorobenzenesulfonyl)‐3,5‐bis[4‐(trifluoromethyl)benzylidene]piperidin‐4‐one, C₂₇H₁₈F₇NO₃S, ( 5 ), (3E,5E)‐1‐(4‐nitrobenzenesulfonyl)‐3,5‐bis[4‐(trifluoromethyl)benzylidene]piperidin‐4‐one, C₂₇H₁₈F₆N₂O₅S, ( 6 ), and (3E,5E)‐1‐(4‐cyanobenzenesulfonyl)‐3,5‐bis[4‐(trifluoromethyl)benzylidene]piperidin‐4‐one dichloromethane monosolvate, C₂₈H₁₈F₆N₂O₃S·CH₂Cl₂, ( 7 ), were prepared by Claisen–Schmidt condensation and N‐sulfonylation. They were characterized by NMR, FT–IR and HRMS (high resolution mass spectrometry). Single‐crystal structure analysis reveals that the two 4‐(trifluoromethyl)phenyl rings on both sides of the piperidone ring in ( 4 )–( 7 ) adopt an E stereochemistry of the olefinic double bonds. Molecules of both ( 4 ) and ( 6 ) are connected by hydrogen bonds into one‐dimensional chains. In ( 5 ) and ( 7 ), pairs of adjacent molecules embrace through intermolecular hydrogen bonds to form a bimolecular combination, which are further extended into a two‐dimensional sheet. The anti‐inflammatory activity data reveal that ( 4 )–( 7 ) significantly inhibit LPS‐induced interleukin (IL‐6) and tumour necrosis factor (TNF‐α) secretion. Most importantly, ( 6 ) and ( 7 ), with strong electron‐withdrawing substituents, display more potential inhibitory effects than ( 4 ) and ( 5 ).     

Synthesis,Characterization, and Biological Evaluation of Novel 3‐(4‐Chlorophenyl)‐2‐(substituted)quinazolin‐4(3H)‐one Derivatives as Multi‐target Anti‐inflammatory Agents

A novel class of 3‐(4‐chlorophenyl)‐2‐(substituted)quinazolin‐4(3H)‐one derivatives were synthesized, and the structure of synthesized compounds was characterized by IR, ¹H NMR, and mass spectroscopy. The newly synthesized compounds ( 4a–g and 6a–g ) were tested for their in vitro cyclooxygenase (COX) inhibition activity. The compounds have inhibitory profile against both COX‐1 and COX‐2, and some of the compounds are found to be selective against COX‐2. The compound 6g showed distinct inhibitory activity on COXs. The synthesized compounds were evaluated for their potential anti‐inflammatory activity as inhibitors of the proinflammatory cytokines IL‐6. Compounds 4d – g showed the highest level of inhibition among all the tested compounds. Thus, our data suggested that these compounds may represent a new class of potent anti‐inflammatory agents.     

A series of substituted (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐phenylprop‐2‐en‐1‐ones

In the molecular structures of a series of substituted chalcones, namely (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐phenylprop‐2‐en‐1‐one, C₂₁H₁₅FO₂, (I), (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐(4‐fluorophenyl)prop‐2‐en‐1‐one, C₂₁H₁₄F₂O₂, (II), (2E)‐1‐(4‐chlorophenyl)‐3‐(2‐fluoro‐4‐phenoxyphenyl)prop‐2‐en‐1‐one, C₂₁H₁₄ClFO₂, (III), (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐(4‐methylphenyl)prop‐2‐en‐1‐one, C₂₂H₁₇FO₂, (IV), and (2E)‐3‐(2‐fluoro‐4‐phenoxyphenyl)‐1‐(4‐methoxyphenyl)prop‐2‐en‐1‐one, C₂₂H₁₇FO₃, (V), the configuration of the keto group with respect to the olefinic double bond is s‐cis. The molecules pack utilizing weak C—H...O and C—H...π intermolecular contacts. Identical packing motifs involving C—H...O interactions, forming both chains and dimers, along with C—H...π dimers and π–π aromatic interactions are observed in the fluoro, chloro and methyl derivatives.     

Conformational study of (Z)‐5‐(4‐chlorobenzylidene)‐2‐[4‐(2‐hydroxyethyl)piperazin‐1‐yl]‐3H‐imidazol‐4(5H)‐one in different environments: insight into the structural properties of bacterial efflux pump inhibitors

The 2‐amine derivatives of 5‐arylidene‐3H‐imidazol‐4(5H )‐one are a new class of bacterial efflux pump inhibitors, the chemical compounds that are able to restore antibiotic efficacy against multidrug resistant bacteria. 5‐Arylidene‐3H‐imidazol‐4(5H )‐ones with a piperazine ring at position 2 reverse the mechanisms of multidrug resistance (MDR) of the particularly dangerous Gram‐negative bacteria E. coli by inhibition of the efflux pump AcrA/AcrB/TolC (a main multidrug resistance mechanism in Gram‐negative bacteria, consisting of a membrane fusion protein, AcrA, a Resistant‐Nodulation‐Division protein, AcrB, and an outer membrane factor, TolC). In order to study the influence of the environment on the conformation of (Z )‐5‐(4‐chlorobenzylidene)‐2‐[4‐(2‐hydroxyethyl)piperazin‐1‐yl]‐3H‐imidazol‐4(5H )‐one, ( 3 ), two different salts were prepared, namely with picolinic acid {systematic name: 4‐[(Z )‐4‐(4‐chlorobenzylidene)‐5‐oxo‐3,4‐dihydro‐1H‐imidazol‐2‐yl]‐1‐(2‐hydroxyethyl)piperazin‐1‐ium pyridine‐2‐carboxylate, C₁₆H₂₀ClN₄O₂⁺·C₆H₄NO₂⁻, ( 3 a )} and 4‐nitrophenylacetic acid {systematic name: 4‐[(Z )‐4‐(4‐chlorobenzylidene)‐5‐oxo‐3,4‐dihydro‐1H‐imidazol‐2‐yl]‐1‐(2‐hydroxyethyl)piperazin‐1‐ium 2‐(4‐nitrophenyl)acetate, C₁₆H₂₀ClN₄O₂⁺·C₈H₆NO₄⁻, ( 3 b )}. The crystal structures of the new salts were determined by X‐ray diffraction. In both crystal structures, the molecule of ( 3 ) is protonated at an N atom of the piperazine ring by proton transfer from the corresponding acid. The carboxylate group of picolinate engages in hydrogen bonds with three molecules of the cation of ( 3 ), whereas the carboxylate group of 4‐nitrophenylacetate engages in hydrogen bonds with only two molecules of ( 3 ). As a consequence of these interactions, different orientations of the hydroxyethyl group of ( 3 ) are observed. The crystal structures are additionally stabilized by both C—H…N [in ( 3 a )] and C—H…O [in ( 3 a ) and ( 3 b )] intermolecular interactions. The geometry of the imidazolone fragment was compared with other crystal structures possessing this moiety. The tautomer observed in the crystal structures presented here, namely 3H‐imidazol‐4(5H )‐one [systematic name: 1H‐imidazol‐5(4H )‐one], is also that most frequently observed in other structures containing this heterocycle.     

Synthesis,Antiproliferative, and Antiplatelet Activities of Oxime‐Containing 3,4‐Dihydroquinolin‐2(1H)‐One Derivatives

Some oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were synthesized and evaluated for their antiplatelet and antiproliferative activities. These compounds were synthesized via alkylation of hydroxyl precursors followed by the reaction with NH₂OH. The preliminary assays indicated that (Z)‐7‐[2‐(4‐fluorophenyl)‐2‐(hydroxyimino)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13c) is the most active against U46619 induced platelet aggregation with an IC₅₀ value of 3.51 μM. For the inhibition of AA‐induced aggregation, (E)‐6‐[2‐(hydroxyimino)propoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (15 ) is the most potent with an IC₅₀ value of 1.85 μM. These oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive against thrombin induced platelet aggregation with an IC₅₀ value of greater than 26.78 μM. For the antiproliferative activity, most of these oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive while (Z)‐7‐[2‐(hydroxyimino)‐2‐(naphthalen‐2‐yl)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13a) exhibited only marginal activities with GI₅₀ value of 7.63, 7.34 and 6.36 μM against the growth of NPC‐TW01, NCI‐H661, and Jurkat respectively.     

Green Synthesis of 1‐(1,2,4‐Triazol‐4‐yl)spiro[azetidine‐2,3′‐(3H)indole]‐2′,4′(1′H)‐diones as Potential Insecticidal Agents

One pot green synthesis of 1‐(1,2,4‐triazol‐4‐yl)spiro[azetidine‐2,3′‐(3H)‐indole]‐2′,4′(1′H)‐diones was carried out by the reaction of indole‐2,3‐diones,4‐amino‐4H‐1,2,4‐triazole and acetyl chloride/chloroacetyl chloride in ionic liquid [bmim]PF₆ with/without using a catalyst. It was also prepared by conventional method via Schiff's bases, 3‐[4H‐1,2,4‐triazol‐4‐yl]imino‐indol‐2‐one. Further, the corresponding phenoxy derivatives were obtained by the reaction of chloro group attached to azetidine ring with phenols. The synthesized compounds were characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR, and FAB mass) data. Evaluation for insecticidal activity against Periplaneta americana exhibited promising results.     

Synthesis of 4‐Aryl‐4,6‐dihydropyrimido[4,5‐d]pyridazine‐2,5(1H,3H)‐diones from Biginelli Compounds

Biginelli compounds 1 were first brominated at Me? C(6) with 2,4,4,6‐tetrabromocyclohex‐2,5‐dien‐1‐one to give Br₂CH? C(6) derivatives 2 . The hydrolysis of the 6‐(dibromomethyl) group of 2c to give the 6‐formyl derivative 3c in the presence of an expensive Ag salt followed by reaction with N₂H₄?H₂O yielded tetrahydropyrimido[4,5‐d]pyridazine‐2,5(1H,3H)‐dione ( 4c ; Scheme 1). However, treatment of the 6‐(dibromomethyl) derivatives 2 directly with N₂H₄?H₂O led to the fused heterocycles 4 in better overall yield (Schemes 1 and 2; Table).     

One‐Pot Synthesis of Novel Pyrrolo[1,2‐a]quinoxaline‐4(5H)‐ones Using Benzene‐1,2‐diamine,Acetylenedicarboxylates, and β‐Nitrostyrene Derivatives

The reaction between a variety of o‐phenylenediamines (=benzene‐1,2‐diamines), dialkyl acetylenedicarboxylates, and derivatives of nitrostyrene (=(E)‐(2‐nitroethenyl)benzene) in the presence of sulfamic acid (SA; H₃NSO₃) as catalyst led to the corresponding pyrrolo[1,2‐a]quinoxaline‐4(5H)‐one derivatives in high yields.     

Synthesis of 4-(4-Methylsulfonylphenyl)-3-phenyl-2(3H)-thiazole Thione Derivatives as New Potential COX-2 Inhibitors

Synthesis of novel 4-（4-methylsulfonylphenyl）-3-phenyl-2（3H）-thiazole thione derivatives with functionalized diarylheterocycle pharmacophore as potential COX-2 inhibitors was described. The title compounds were synthesized by cyclocondensation of corresponding dithiocarbamate and 2-bromo-1-（4-methylsulfonylphenyl）ethanone, followed by dehydration with H2SO4. All of the target compounds were characterized by ^1H NMR, IR and mass spectral data.     

Synthesis and Antibacterial Activity of Novel (4‐Fluorophenyl)(4‐(naphthalen‐2‐yl)‐6‐aryl‐2‐thioxo‐2,3‐dihydropyrimidin‐1(6H)‐yl)methanone Derivatives

A novel series of (4‐fluorophenyl)(4‐(naphthalen‐2‐yl)‐6‐aryl‐2‐thioxo‐2,3‐dihydropyrimidin‐1(6H)‐yl)methanone derivatives were synthesized from reaction of 6‐(naphthalen‐2‐yl)‐4‐aryl‐3,4‐dihydropyrimidine‐2(1H)‐thiones with 4‐fluorobenzoylchloride in dichloromethane in the presence of triethylamine. The synthesized compounds were screened for antibacterial activity against Gram positive bacteria, namely, Staphylococcus aureus ATCC25923 and Listeria monocytogenes MTCC657, and Gram negative bacteria, namely, Escherichia coli ATCC25922 and Klebsiella pneumoniae ATCC700603, respectively. Some of the tested compounds showed significant antimicrobial activity.     

Synthesis of 4‐(2‐hydroxyphenyl)‐1‐phenyl‐1,2,4‐triazolidine‐3,5‐dione derivatives through cyclic transformations of 3‐(2‐phenylcarbazoyl)‐2(3H)‐benzoxazolone derivatives

Four 3‐(3‐benzylidene‐2‐phenylcarbazoyl)‐2(3H)‐benzoxazolone derivatives 3 have been synthesized from benzoxazolone derivatives 1 and benzaldehyde N‐chloroformylphenylhydrazone 2. By acid hydrolysis, these compounds yielded 3‐(2‐phenylcarbazoyl)‐2(3H)benzoxazolone derivatives 4 which were not isolated and were transformed via an intramolecular reaction into 4‐(2‐hydroxyphenyl)‐1‐phenyl‐1,2,4‐triazolidine‐3,5‐dione derivatives 5 in a good yield. Attempts to cyclize these compounds by intramolecular elimination of water into tricyclic compounds 6 with various dehydrating agents were unsuccessful.     

Synthesis and anti‐HIV activity of n‐(3‐amino‐3,4‐dihydro‐4‐oxopyrimidin‐2‐yl)‐4‐chloro‐2‐mercapto‐5‐methylbenzenesulfonamide derivatives

A series of N‐(3‐amino‐3,4‐dihydro‐4‐oxopyrimidin‐2‐yl)‐4‐chloro‐2‐mercapto‐5‐methylbenzenesulfonamide derivatives 10‐17 have been synthesized as potential anti‐HIV agents. The in vitro anti‐HIV‐1 activity of these compounds has been tested at the national Cancer Institute (Bethesda, MD), and the structure‐activity relationships are discussed. The selected N‐[3‐amino‐3,4‐dihydro‐6‐(tert‐butyl)‐4‐oxothieno[2,3‐e]pyrimidin‐2‐yl]‐4‐chloro‐2‐metcapto‐5‐methylbenzenesulfonamide ( 14 ) showed good anti‐HIV‐1 activity with 50% effective concentration (EC₅₀) value of 15 μM and weak cytotoxic effect (IC₅₀ = 106 μM).     

Seven 3‐methylidene‐1H‐indol‐2(3H)‐ones related to the multiple‐receptor tyrosine kinase inhibitor sunitinib

The solid‐state structures of a series of seven substituted 3‐methylidene‐1H‐indol‐2(3H)‐one derivatives have been determined by single‐crystal X‐ray diffraction and are compared in detail. Six of the structures {(3Z)‐3‐(1H‐pyrrol‐2‐ylmethylidene)‐1H‐indol‐2(3H)‐one, C₁₃H₁₀N₂O, (2a); (3Z)‐3‐(2‐thienylmethylidene)‐1H‐indol‐2(3H)‐one, C₁₃H₉NOS, (2b); (3E)‐3‐(2‐furylmethylidene)‐1H‐indol‐2(3H)‐one monohydrate, C₁₃H₉NO₂·H₂O, (3a); 3‐(1‐methylethylidene)‐1H‐indol‐2(3H)‐one, C₁₁H₁₁NO, (4a); 3‐cyclohexylidene‐1H‐indol‐2(3H)‐one, C₁₄H₁₅NO, (4c); and spiro[1,3‐dioxane‐2,3′‐indolin]‐2′‐one, C₁₁H₁₁NO₃, (5)} display, as expected, intermolecular hydrogen bonding (N—H...O=C) between the 1H‐indol‐2(3H)‐one units. However, methyl 3‐(1‐methylethylidene)‐2‐oxo‐2,3‐dihydro‐1H‐indole‐1‐carboxylate, C₁₃H₁₃NO₃, (4b), a carbamate analogue of (4a) lacking an N—H bond, displays no intermolecular hydrogen bonding. The structure of (4a) contains three molecules in the asymmetric unit, while (4b) and (4c) both contain two independent molecules.     

Comparison of the structure of (E)‐2‐(2‐benzylidenehydrazinylidene)quinoxaline with those of its chloro‐ and bromobenzylidene analogues

(E)‐2‐(2‐Benzylidenehydrazinylidene)quinoxaline, C₁₅H₁₂N₄, crystallized with two molecules in the asymmetric unit. The structures of six halogen derivatives of this compound were also investigated: (E)‐2‐[2‐(2‐chlorobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁ClN₄; (E)‐2‐[2‐(3‐chlorobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁ClN₄; (E)‐2‐[2‐(4‐chlorobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁ClN₄; (E)‐2‐[2‐(2‐bromobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁BrN₄; (E)‐2‐[2‐(3‐bromobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁BrN₄; (E)‐2‐[2‐(4‐bromobenzylidene)hydrazinylidene]quinoxaline, C₁₅H₁₁BrN₄. The 3‐Cl and 3‐Br compounds are isomorphous, as are the 4‐Cl and 4‐Br compounds. In all of these compounds, it was found that the supramolecular structures are governed by similar predominant patterns, viz. strong intermolecular N—H...N(pyrazine) hydrogen bonds supplemented by weak C—H...N(pyrazine) hydrogen‐bond interactions in the 2‐ and 3‐halo compounds and by C—H...Cl/Br interactions in the 4‐halo compounds. In all compounds, there are π–π stacking interactions.     

2‐Amino‐5‐(2‐pyridyl)‐thiadiazole as Bidentate Ligand

The amino substituted bidentate chelating ligand 2‐amino‐5‐(2‐pyridyl)‐1,3,4‐thiadiazole (H₂ L ) was used to prepare 3:1‐type coordination compounds of iron(II), cobalt(II) and nickel(II). In the iron(II) perchlorate complex [Fe^II(H₂ L )₃](ClO₄)₂·0.6MeOH·0.9H₂O a 1:1 mixture of mer and fac isomers is present whereas [Fe^II(H₂ L )₃](BF₄)₂·MeOH·H₂O, [Co^II(H₂ L )₃](ClO₄)₂·2H₂O and [Ni^II(H₂ L )₃](ClO₄)₂·MeOH·H₂O feature merely mer derivatives. Moessbauer spectroscopy and variable temperature magnetic measurements revealed the [Fe^II(H₂ L )₃]²⁺ complex core to exist in the low‐spin state, whereas the [Co^II(H₂ L )₃]²⁺ complex core resides in its high‐spin state, even at very low temperatures.     

Synthesis and Antiplatelet‐Activity Evaluation of α‐Methylidene‐γ‐butyrolactones Bearing 3,4‐Dihydroquinolin‐2(1H)‐one Moieties

In continuation of our search for potent antiplatelet agents, we have synthesized and evaluated several α‐methylidene‐γ‐butyrolactones bearing 3,4‐dihydroquinolin‐2(1H)‐one moieties. O‐Alkylation of 3,4‐dihydro‐8‐hydroxyquinolin‐2(1H)‐one ( 1 ) with chloroacetone under basic conditions afforded 3,4‐dihydro‐8‐(2‐oxopropoxy)quinolin‐2(1H)‐one ( 2a ) and tricyclic 2,3,6,7‐tetrahydro‐3‐hydroxy‐3‐methyl‐5H‐pyrido[1,2,3‐de][1,4]benzoxazin‐5‐one ( 3a ) in a ratio of 1 : 2.84. Their Reformatsky‐type condensation with ethyl 2‐(bromomethyl)prop‐2‐enoate furnished 3,4‐dihydro‐8‐[(2,3,4,5‐tetrahydro‐2‐methyl‐4‐methylidene‐5‐oxofuran‐2‐yl)methoxy]quinolin‐2(1H)‐one ( 4a ), which shows antiplatelet activity, in 70% yield. Its 2′‐Ph derivatives, and 6‐ and 7‐substituted analogs were also obtained from the corresponding 3,4‐dihydroquinolin‐2(1H)‐ones via alkylation and the Reformatsky‐type condensation. Of these compounds, 3,4‐dihydro‐7‐[(2,3,4,5‐tetrahydro‐4‐methylidene‐5‐oxo‐2‐phenylfuran‐2‐yl)methoxy]quinolin‐2(1H)‐one ( 10b ) was the most active against arachidonic acid (AA) induced platelet aggregation with an IC₅₀ of 0.23 μM . For the inhibition of platelet‐activating factor (PAF) induced aggregation, 6‐{[2‐(4‐fluorophenyl)‐2,3,4,5‐tetrahydro‐4‐methylidene‐5‐oxofuran‐2‐yl]methoxy}‐3,4‐dihydroquinolin‐2(1H)‐one ( 9c ) was the most potent with an IC₅₀ value of 1.83 μM .     

N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide

N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide, C₁₉H₁₉BrN₂O₂, (I), and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide, C₂₀H₂₁BrN₂O₂, (II), are an homologous pair of 1,8‐naphthalimide derivatives. The naphthalimide units are planar and each piperidine substituent adopts a chair conformation. This study emphasizes the importance of π‐stacking interactions, often augmented by other contacts, in determining the crystal structures of 1,8‐naphthalimide derivatives.     

Metabolism of Deuterated Isomeric 6,7‐Dihydroxydodecanoic Acids in Saccharomyces cerevisiae – Diastereo‐ and Enantioselective Formation and Characterization of 5‐Hydroxydecano‐4‐lactone (=4,5‐Dihydro‐5‐(1‐hydroxyhexyl)furan‐2(3H)‐one) Isomers

The chemical synthesis of deuterated isomeric 6,7‐dihydroxydodecanoic acid methyl esters 1 and the subsequent metabolism of esters 1 and the corresponding acids 1a in liquid cultures of the yeast Saccharomyces cerevisiae was investigated. Incubation experiments with (6R,7R)‐ or (6S,7S)‐6,7‐dihydroxy(6,7‐²H₂)dodecanoic acid methyl ester ((6R,7R)‐ or (6S,7S)‐(6,7‐²H₂)‐ 1 , resp.) and (±)‐threo‐ or (±)‐erythro‐6,7‐dihydroxy(6,7‐²H₂)dodecanoic acid ((±)‐threo‐ or (±)‐erythro‐(6,7‐²H₂)‐ 1a , resp.) elucidated their metabolic pathway in yeast (Tables 1–3). The main products were isomeric ²H‐labeled 5‐hydroxydecano‐4‐lactones 2 . The absolute configuration of the four isomeric lactones 2 was assigned by chemical synthesis via Sharpless asymmetric dihydroxylation and chiral gas chromatography (Lipodex ^® E). The enantiomers of threo‐ 2 were separated without derivatization on Lipodex ^® E; in contrast, the enantiomers of erythro‐ 2 could be separated only after transformation to their 5‐O‐(trifluoroacetyl) derivatives. Biotransformation of the methyl ester (6R,7R)‐(6,7‐²H₂)‐ 1 led to (4R,5R)‐ and (4S,5R)‐(2,5‐²H₂)‐ 2 (ratio ca. 4 : 1; Table 2). Estimation of the label content and position of (4S,5R)‐(2,5‐²H₂)‐ 2 showed 95% label at C(5), 68% label at C(2), and no ²H at C(4) (Table 2). Therefore, oxidation and subsequent reduction with inversion at C(4) of 4,5‐dihydroxydecanoic acid and transfer of ²H from C(4) to C(2) is postulated. The 5‐hydroxydecano‐4‐lactones 2 are of biochemical importance: during the fermentation of Streptomyces griseus, (4S,5R)‐ 2 , known as L‐factor, occurs temporarily before the antibiotic production, and (?)‐muricatacin (=(4R,5R)‐5‐hydroxy‐heptadecano‐4‐lactone), a homologue of (4R,5R)‐ 2 , is an anticancer agent.