Two isomeric 2‐[4‐chloro‐2‐fluoro‐5‐(prop‐2‐ynyloxy)phenyl]hexahydro­isoindole‐1,3‐dione compounds

The molecular structures of 2‐[4‐chloro‐2‐fluoro‐5‐(prop‐2‐ynyloxy)phenyl]‐1,3,4,5,6,7‐hexahydro­isoindole‐1,3‐dione, C₁₇H₁₃ClFNO₃, (I), and the isomeric compound 2‐[4‐chloro‐2‐fluoro‐5‐(prop‐2‐ynyloxy)phenyl]‐cis‐1,3,3a,4,7,7a‐hexahydro­isoindole‐1,3‐dione, (II), are, as anticipated, significantly different in their conformations and in the distances between the farthest two atoms. The six‐membered ring of the 1,3,4,5,6,7‐hexahydro­isoindole‐1,3‐dione moiety in (I) adopts a half‐chair conformation. The dihedral angle between the five‐membered dione ring of (I) and the benzene ring is 50.96 (7)°. The six‐membered ring of the cis‐1,3,3a,4,7,7a‐hexahydro­isoindole‐1,3‐dione moiety in (II) adopts a boat conformation. The dihedral angle in (II) between the five‐membered dione ring and the benzene ring is 61.03 (13)°. In the crystal structures, the molecules are linked by C—H⋯O hydrogen bonds and weak π–π interactions. Compound (I) is a much more potent herbicide than (II). The Cl⋯H distances between the farthest two atoms in (I) and (II) are 11.37 and 9.97 Å, respectively.     

Isoindolones from Lasiosphaera fenzlii Reich. and Their Bioactivities

Two new, 1 and 2 , along with one known isoindolone, 3 , were isolated from the AcOEt extract of Lasiosphaera fenzlii Reich . The structures of these compounds were determined as 4,6‐dihydroxy‐1H‐isoindole‐1,3(2H)‐dione ( 1 ), 4,6‐dihydroxy‐2,3‐dihydro‐1H‐isoindol‐1‐one ( 2 ), and clitocybin A ( 3 ) on the basis of chemical and spectroscopic evidences. The bioactivity assays revealed that all of them were devoid of significant cytotoxicities against tumor cells, whereas 1 exhibited potent antiangiogenic activity by inhibiting the secretion of vascular endothelial growth factor (VEGF) in A549 cells.     

Structural and theoretical study of four novel norcantharidine derivatives: two new cases of conditional isomorphism

Structural and theoretical studies of four novel 5,6‐dehydronorcantharidine ( DNCA )/norcantharidine ( NCA ) derivatives, namely (3aR,4S,7R,7aS)‐2‐phenyl‐3a,4,7,7a‐tetrahydro‐4,7‐epoxy‐1H‐isoindole‐1,3(2H)‐dione, C₁₄H₁₁NO₃ ( DNCA‐A ), (3aR,4S,7R,7aS)‐2‐(4‐nitrophenyl)‐3a,4,7,7a‐tetrahydro‐4,7‐epoxy‐1H‐isoindole‐1,3(2H)‐dione, C₁₄H₁₀N₂O₅ ( DNCA‐NA ), (3aR,4S,7R,7aS)‐2‐(4‐nitrophenyl)‐3a,4,5,6,7,7a‐hexahydro‐1H‐4,7‐epoxyisoindole‐1,3(2H)‐dione, C₁₄H₁₂N₂O₅ ( NCA‐NA ), and (3aR,4S,7R,7aS)‐2‐(2‐hydroxyethyl)‐3a,4,5,6,7,7a‐hexahydro‐1H‐4,7‐epoxyisoindole‐1,3(2H)‐dione, C₁₀H₁₃NO₄ ( NCA‐AE ), are reported. The supramolecular interactions and single‐crystal structural characteristics of these molecules, together with the crystal structures of four other similar molecules, i.e. NCA‐A (the 4‐phenyl derivative of NCA‐NA ), DNCA‐AE (the 5,6‐unsaturated derivative of NCA‐AE ), DNCA and NCA , were analysed. Surprisingly, DNCA‐A and NCA‐A , as well as DNCA–NA and NCA‐NA , proved to be isomorphic, while DNCA‐AE and NCA‐AE , as well as DNCA and NCA , have very different crystal structures. These are very rare isostructural examples between unsaturated and saturated oxanorbornene/oxanorbornane derivatives. To further explore how noncovalent interactions (NCIs) affect the degree of isomorphism in this particular series of rigid molecules where there is a fairly limited conformational degree of freedom, all four pairs of crystal structures were analyzed in parallel. The differentiation in NCIs which entails the packing mode of similar molecules is supported by energy calculations based on real or exchanged crystal structures. Our results show that minor structural differences may result in very different supramolecular interactions, and so lead to altered packing modes in the crystalline solids. Even if isostructurality sometimes occurs, the possibility of various molecular packing types cannot be ruled out. On the other hand, isomorphism may just be the result of kinetic possibilities instead of relative thermodynamic stabilities. Though crystal structure prediction is formidable, the comparison method based on existing crystal structures and quantum calculations can be used to predict the probability of isomorphism. This understanding will help us to design new norbornene derivatives with specified structures.     

Synthesis of 1H‐quinazoline‐2,4‐diones from 2‐aminobenzonitriles by fixation of carbon dioxide with amidine moiety supported polymer at atmospheric pressure

1H‐Quinazoline‐2,4‐diones, which are key intermediates in the synthesis of medicines, were successfully synthesized from 2‐aminobenzonitriles by the fixation of CO₂ in the presence of a polystyrene derivative bearing amidine moiety [poly(amidine)]. A model reaction, that is, the reaction of 2‐aminobenzonitrile ( 1a ) with CO₂ in the presence of N‐methyltetrahydropyrimidine ( MTHP ) revealed that a catalytic amount of MTHP afforded 1H‐quinazoline‐2,4‐dione ( 2a ) quantitatively at atmospheric pressure. Several 1H‐quinazoline‐2,4‐diones ( 2a ‐ 2c ) were successfully synthesized from the corresponding 2‐aminobenzonitriles ( 1a ‐ 1c ) in the presence of poly(amidine). The poly(amidine) could easily be separated from the reaction mixture by filtration and reused in subsequent reactions owing to the heterogeneous system. These demonstrated that poly(amidine) is a useful heterogeneous polymer‐supported reagent for the synthesis of 1H‐quinazoline‐2,4‐diones from CO₂. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 653–657, 2009     

Reaction of 2,3‐Dichloro‐1,4‐Naphthoquinone with 1‐Phenylbiguanide and 2‐Guanidinebenzimidazole

When 2,3‐dichloro‐1,4‐naphthoquinone (DCHNQ) ( 1 ) is allowed to react with 1‐phenylbiguanide (PBG) ( 2 ), 4‐chloro‐2,5‐dihydro‐2,5‐dioxonaphtho[1,2‐d]imidazole‐3‐carboxylic acid phenyl amide ( 4 ), 6‐chloro‐8‐phenylamino‐9H‐7,9,11‐triaza‐cyclohepta[a]naphthalene‐5,10‐dione ( 5 ) and 4‐dimethyl‐amino‐5,10‐dioxo‐2‐phenylimino‐5,10‐dihydro‐2H‐benzo[g]quinazoline‐1‐carboxylic acid amide ( 6 ) were obtained. While on reacting 1 with 2‐guanidinebenzimidazole (GBI) ( 3 ) the products are 3‐(1H‐benzoimidazol‐2‐yl)‐4‐chloro‐3H‐naphtho[1,2‐d]imidazole‐2,5‐dione ( 7 ) and 3‐[3‐(1H‐benzoimidazol‐2‐yl)‐ureido]‐1,4‐dioxo‐1,4‐dihydronaphthalene‐2‐carboxylic acid dimethylamide ( 8 ).     

A New and Convenient Synthesis of Amino‐phthalimide (1H‐Isoindole‐1,3(2H)‐dione) Derivatives and Their Photoluminescent Properties

A new and convenient synthesis for amino‐phthalimide (1H‐isoindole‐1,3(2H)‐dione) derivatives has been developed starting from an α,β‐unsaturated ketone. The ketones were reacted with amines to give aromatic amine products. This is the first time that substituted amine groups have been incorporated in aromatic rings. The mechanism of the product formation is rationalized by the 1,2‐addition of amines to ketones. All aromatic compounds exhibited high fluorescence properties at the blue‐green region.     

New Long‐Chain Esters and Adenine Analogs from the Leaves of Formosan Bridelia balansae

Six new compounds, including the two long‐chain esters balansenate I (=6,8,11‐trimethyldodecanoic acid (2E)‐3‐methylhexadec‐2‐enyl ester; 1 ) and balansenate II (=10,12,15‐trimethylhexadedecanoic acid (2E)‐3‐methylhexadec‐2‐enyl ester; 2 ), the eburicane‐like triterpenoid bridelone (=hexadecahydro‐4,4,10,13,14‐pentamethyl‐17‐(5‐methyl‐1,4‐dimethylenehexyl)‐3H‐cyclopenta[a]phenanthren‐3‐one; 3 ), the ‘deimino‐xanthine', bridelonine (=5‐(3‐methylbut‐2‐enyl)pyrrolo[3,4‐d]imidazole‐4,6(1H,5H)‐dione; 6 ), and the two adenine analogs 9‐(3‐methylbut‐2‐enyl)adenine ( 7 ) and 1‐(3‐methylbut‐2‐enyl)adenine ( 8 ), besides three known compounds, i.e., N⁶‐(3‐methylbut‐2‐enyl)adenine ( 4 ), 3‐(3‐methylbut‐2‐enyl)adenine ( 5 ), and adenine ( 9 ), were isolated from the leaves of Formosan Bridelia balansae. The novel skeleton of 6 consists of a fused pyrrolidine‐2,5‐dione and imidazole moiety. The already known adenines 7 and 8 were isolated for the first time from a plant. The structures of the isolated compounds were elucidated by spectroscopic analyses.     

New synthesis and reactivity of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with binucleophilic amines

3‐(Bromoacetyl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one was synthesized by the reaction of dehydroacetic acid (DHAA) with bromine in glacial acetic acid. Novel heterocyclic products were synthesized from the reaction of bromo‐DHAA with alkanediamines, phenylhydrazines, ortho‐phenylenediamines, and ortho‐aminobenzenethiol. The obtained new products 3‐(2‐N‐substituted‐acetyl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐ones, 4‐hydroxy‐3‐[1‐hydroxy‐2‐(2‐phenylhydrazinyl)vinyl]‐6‐methyl‐2H‐pyran‐2‐one, 1‐(2,4‐dinitrophenyl)‐7‐methyl‐2,3‐dihydro‐1H‐pyrano[4,3‐c]pyridazine‐4,5‐dione, 3‐(3,4‐dihydroquinoxalin‐2‐yl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one/3‐(3,4‐dihydroquinoxalin‐2‐yl)‐6‐methyl‐2H‐pyran‐2,4(3H)‐dione, 6‐methyl‐3‐(3,4‐dihydroquinoxalin‐2‐yl)‐2H‐pyran‐2,4(3H)‐dione, and (E)‐3‐(2H‐benzo[b][1,4]thiazin‐3(4H)‐ylidene)‐6‐methyl‐2H‐pyran‐2,4(3H)‐dione were fully characterized by IR, ¹H and ¹³C NMR, and mass spectra. J. Heterocyclic Chem., 2011.     

Two 2D Metal‐organic Networks Based on a Rigid Imidazolate/Sulfonate Functionalized Ligand – Effect of the Coordination Modes of the Ligand on Crystal Structures

A rigid imidazolate/sulfonate functionalized ligand, 6‐(4‐sulfonatopheny)imidazo[4, 5‐f]isoindole‐5, 7‐dione (SPID) was designed and used for assembling reactions with Mn²⁺ and Cu²⁺ ions. Two 2D frameworks compounds, [Mn(H_‐1SPID)₂(DMAC)₂] ( 1 ) and [Cu(H_‐2SPID)(H₂O)₂] · 0.7DMAC · 0.3H₂O ( 2 ) (DMAC = N,N‐dimethylacetamide) were obtained. Single crystal X‐ray analyses show that 1 has a 2D (4, 4)‐net based on 4‐connected Mn²⁺ nodes and μ₂‐coordinated H_‐1SPID spacers, whereas compound 2 has a 2D (6, 3)‐net built of 3‐connected Cu²⁺ nodes and μ₃‐coordinated H_‐2SPID spacers. Additionally, the thermal behavior of 1 and 2 is presented.     

Synthesis and Properties of Brominated 6,6'-Dimethyl-[2,2'-bi-1H-indene]-3,3'-diethyl-3,3'-dihydroxy-1,1 '-diones

Photochromic 6‐bromomethyl‐6′‐methyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 2 ), 6,6′‐ bis(bromomethyl)‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 3 ) and 6,6′‐bis(dibromomethyl)‐[2,2′‐ bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 4 ) have been synthesized from 6,6′‐dimethyl‐[2,2′‐bi‐1H‐ indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 1 ). The single crystal of 4 was obtained and its crystal structure was analyzed. The results indicate that in crystal 4 , molecular arrangement is defective tightness compared with its precursor 1 . Besides, UV‐Vis absorption spectra in CH₂Cl₂ solution, photochromic and photomagnetic properties in solid state of 2 , 3 and 4 were also investigated. The results demonstrate that when the hydrogen atoms in the methyl group on the benzene rings of biindenylidenedione were substituted by bromines, its properties could be affected considerably.     

Further Prenylated Bi‐ and Tricyclic Phloroglucinol Derivatives from Hypericum papuanum

From the petroleum‐ether extract of the dried aerial parts of Hypericum papuanum, three new prenylated tricyclic and four new bicyclic acylphloroglucinol derivatives were isolated by bioactivity‐guided fractionation. The structures of the bicyclic compounds enaimeone A, B, and C ( 1 / 1a , 2 / 2a , and 3 / 3a , resp.) were elucidated as rel‐(1R,5R,6S)‐4‐hydroxy‐6‐(1‐hydroxy‐1‐methylethyl)‐5‐methyl‐1‐(3‐methylbut‐2‐enyl)‐3‐(2‐methylpropanoyl)‐bicyclo[3.2.1]oct‐3‐ene‐2,8‐dione ( 1 / 1a ), rel‐(1R,5R,6R)‐4‐hydroxy‐6‐(1‐hydroxy‐1‐methylethyl)‐5‐methyl‐1‐(3‐methylbut‐2‐enyl)‐3‐(2‐methylpropanoyl)bicyclo[3.2.1]oct‐3‐ene‐2,8‐dione ( 2 / 2a ), rel‐(1R,5R,6R)‐4‐hydroxy‐6‐(1‐hydroxy‐1‐methylethyl)‐5‐methyl‐3‐(2‐methylbutanoyl)‐1‐(3‐methylbut‐2‐enyl)bicyclo[3.2.1]oct‐3‐ene‐2,8‐dione ( 3 / 3a ). The tricyclic isolates 8‐hydroxy‐3β‐(1‐hydroxy‐1‐methylethyl)‐4,4,7‐trimethyl‐9‐(2‐methylpropanoyl)‐5βH‐tricyclo[5.3.1.0^1,5]undec‐8‐ene‐10,11‐dione ( 4 ), 8‐hydroxy‐3α‐(1‐hydroxy‐1‐methylethyl)‐4,4,7‐trimethyl‐9‐(2‐methylpropanoyl)‐5βH‐tricyclo[5.3.1.0^1,5]undec‐8‐ene‐10,11‐dione ( 5 ), and 8‐hydroxy‐3α‐(1‐hydroxy‐1‐methylethyl)‐4,4,7‐trimethyl‐9‐(2‐methylbutanoyl)‐5βH‐tricyclo[5.3.1.0^1,5]undec‐8‐ene‐10,11‐dione ( 6 ), and their corresponding tautomers 4a , 5a , and 6a , were named 1′‐hydroxyialibinones A, B, and D, respectively. Oxidative decomposition of furonewguinone A (=2,3,3a,5‐tetrahydro‐3a‐hydroxy‐2‐(1‐hydroxy‐1‐methylethyl)‐5‐methyl‐5‐(3‐methylbut‐2‐enyl)‐7‐(2‐methylpropanoyl)‐benzofuran‐4,6‐dione; 7 ) led to furonewguinone B (=3,3a,7,7a‐tetrahydro‐3a,6,7a‐trihydroxy‐2‐(1‐hydroxy‐1‐methylethyl)‐7‐methyl‐7‐(3‐methylbut‐2‐enyl)‐5‐(2‐methylpropanoyl)benzofuran‐4(2H)‐one; 8 / 8a ). Structure elucidation was based on extensive 1D and 2D NMR studies, as well as on data derived from mass spectrometry. Furthermore, the cytotoxicity towards KB nasopharyngeal carcinoma cells and the antibacterial activity were determined.     

Four 7‐aryl‐substituted pyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐diones: similar molecular structures but different crystal structures

Molecules of 1,3‐dimethyl‐7‐(4‐methylphenyl)pyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione, C₁₆H₁₅N₃O₂, (I), are linked by paired C—H...O hydrogen bonds to form centrosymmetric R₂²(10) dimers, which are linked into chains by a single π–π stacking interaction. A single C—H...O hydrogen bond links the molecules of 7‐(biphenyl‐4‐yl)‐1,3‐dimethylpyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione, C₂₁H₁₇N₃O₂, (II), into C(10) chains, which are weakly linked into sheets by a π–π stacking interaction. In 7‐(4‐fluorophenyl)‐3‐methylpyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione, C₁₄H₁₀FN₃O₂, (III), an N—H...O hydrogen bond links the molecules into C(6) chains, which are linked into sheets by a π–π stacking interaction. The molecules of 7‐(4‐methoxyphenyl)‐3‐methylpyrido[2,3‐d]pyrimidine‐2,4(1H,3H)‐dione, C₁₅H₁₃N₃O₃, (IV), are also linked into C(6) chains by an N—H...O hydrogen bond, but here the chains are linked into sheets by a combination of two independent C—H...π(arene) hydrogen bonds.     

Cyclic imides and an open‐chain amide carboxylic acid from the facile reaction of cis‐cyclohexane‐1,2‐carboxylic anhydride with the isomeric monofluoroanilines

The structures of the cyclic imides cis‐2‐(2‐fluorophenyl)‐3a,4,5,6,7,7a‐hexahydroisoindole‐1,3‐dione, C₁₄H₁₄FNO₂, (I), and cis‐2‐(4‐fluorophenyl)‐3a,4,5,6,7,7a‐hexahydroisoindoline‐1,3‐dione, C₁₄H₁₄FNO₂, (III), and the open‐chain amide acid rac‐cis‐2‐[(3‐fluorophenyl)carbamoyl]cyclohexane‐1‐carboxylic acid, C₁₄H₁₆FNO₃, (II), are reported. Cyclic imides (I) and (III) are conformationally similar, with comparable ring rotations about the imide N—C_ar bond [the dihedral angles between the benzene ring and the five‐membered isoindole ring are 55.40 (8)° for (I) and 51.83 (7)° for (III)]. There are no formal intermolecular hydrogen bonds involved in the crystal packing of either (I) or (III). With the acid (II), in which the meta‐related F‐atom substituent is rotationally disordered (0.784:0.216), the amide group lies slightly out of the benzene plane [the interplanar dihedral angle is 39.7 (1)°]. Intermolecular amide–carboxyl N—H...O hydrogen‐bonding interactions between centrosymmetrically related molecules form stacks extending down b, and these are linked across c by carboxyl–amide O—H...O hydrogen bonds, giving two‐dimensional layered structures which lie in the (011) plane. The structures reported here represent examples of compounds analogous to the phthalimides or phthalanilic acids and have little precedence in the crystallographic literature.     

Study of the reactions of 3‐acetoacetyl‐7‐methyl‐2H,5H‐pyrano[4,3‐b]pyran‐2,5‐dione with aromatic amines

The reactions of 3‐acetoacetyl‐7‐methyl‐2H,5H‐pyrano[4,3‐b]pyran‐2,5‐dione with aromatic amines afforded 3‐(arylaminomethylene)‐6‐methylpyran‐2,4‐dione. Our results allowed the correction of the structures reported in the literature for the products of these reactions.     

Practical Synthesis of New β‐Diketone‐Connected Bipyridine and Its Conversion to Pyrazole‐Centered Bipyridine Ligand

Two new polydentate ligands, 1‐(6‐hydroxymethyl‐2‐pyridyl)‐3‐(2‐pyridyl)‐propane‐1,3‐dione (6) and 1,3‐bis(6‐hydroxymethyl‐2‐pyridyl)‐propane‐1, 3‐dione (8), have been synthesized starting from 2,6‐pyridinedicarboxylic acid by conventional esterification, reduction, and condensation reactions. They were further converted to two new polydentate ligands, 3‐(6‐hydroxymethyl‐2‐pyridyl)‐5‐(2‐pyridyl)‐1H‐pyrazole (7) and 3,5‐bis(6‐hydroxymethyl‐2‐pyridyl)‐1H‐pyrazole (9), by reaction with hydrazine hydrate. These four compounds were characterized by proton nuclear magnetic resonance (¹H NMR), electrospray ionization‐mass spectrum (ESI‐MS), infrared spectrum (IR), and elemental analyses. The structure of 9 was also determined by X‐ray diffraction.     

Synthesis and reactions of 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]‐quinazolin‐9‐one and 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one

The reaction of 3‐N‐(2‐mercapto‐4‐oxo‐4H‐quinazolin‐3‐yl)acetamide ( 1 ) with hydrazine hydrate yielded 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 2 ). The reaction of 2 with o‐chlorobenzaldehyde and 2‐hydroxy‐naphthaldehyde gave the corresponding 3‐arylidene amino derivatives 3 and 4 , respectively. Condensation of 2 with 1‐nitroso‐2‐naphthol afforded the corresponding 3‐(2‐hydroxy‐naphthalen‐1‐yl‐diazenyl)‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 5 ), which on subsequent reduction by SnCl₂ and HCl gave the hydrazino derivative 6. Reaction of 2 with phenyl isothiocyanate in refluxing ethanol yielded thiourea derivative 7. Ring closure of 7 subsequently cyclized on refluxing with phencyl bromide, oxalyl dichloride and chloroacetic acid afforded the corresponding thiazolidine derivatives 8, 9 and 10 , respectively. Reaction of 2‐mercapto‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 11 ) with hydrazine hydrate afforded 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 12 ). The reactivity 12 towards carbon disulphide, acetyl acetone and ethyl acetoacetate gave 13, 14 and 15 , respectively. Condensation of 12 with isatin afforded 2‐[N‐(2‐oxo‐1,2‐dihydroindol‐3‐ylidene)hydrazino]‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 16 ). 2‐(4‐Oxo‐3‐phenylamino‐3,4‐dihydroquinazolin‐2‐ylamino)isoindole‐1,3‐dione ( 17 ) was synthesized by the reaction of 12 with phthalic anhydride. All isolated products were confirmed by their ir, ¹H nmr, ¹³C nmr and mass spectra.     

Synthesis of Indeno[1,2‐d]pyrimidin‐5‐Ones and Their Fluorescence in Solid State

New fluorescent compounds, 2‐substituted indeno[1,2‐d]pyrimidin‐5‐ones ( 3a , 3b , 3c , 3d ) were synthesized in good yield by the reaction of 2‐[bis(methylsulfanyl)methylene]indan‐1,3‐dione ( 1 ) with the respective amidine derivatives [guanidine carbonate ( 2a ), acetamidine hydrochloride ( 2b ), S‐methylisothiourea sulfate ( 2c ), and S‐benzylisothiourea sulfate ( 2d )]. 4‐Substituted amino‐2‐aminoindeno[1,2‐d]pyrimidin‐5‐ones ( 7b , 7c , 7d ) were synthesized by a one‐pot reaction of 1 , 2a and the respective amine compounds ( 4b , 4c , 4d ) in pyridine. These fused pyrimidine derivatives showed fluorescence in the solid state.     

Pakistolides A and B,Novel Enzyme Inhibitory and Antioxidant Dimeric 4‐(Glucosyloxy)Benzoates from Berchemia pakistanica

Pakistolides A and B, novel dimeric β‐(glucosyloxy)benzoates were isolated from Berchemia pakistanica and assigned structures 1 and 2 on the basis of extensive NMR studies. In addition, the known compounds 7,5′‐dimethoxy‐3,5,2′‐trihydroxyflavone (=3,5‐dihydroxy‐2‐(2‐hydroxy‐5‐methoxyphenyl)‐7‐methoxy‐4H‐1‐benzopyran‐4‐one), 4′,5‐dihydroxy‐3,6,7‐trimethoxyflavone (=5‐hydroxy‐2‐(4‐hydroxyphenyl)‐3,6,7‐trimethoxy‐4H‐1‐benzopyran‐4‐one), 5,6‐dihydroxy‐4,7‐dimethoxy‐2‐methylanthracene‐9,10‐dione, and 1,3,4‐trihydroxy‐6,7,8‐trimethoxy‐2‐methylanthracene‐9,10‐dione were reported for the first time from the genus Berchemia. Both 1 and 2 showed significant α‐glucosidase and lipoxygenase inhibitory activities, while 2 also showed antioxidant potential.     

Diels‐alder reactions of 2‐(2‐nitroethenyl)‐1H‐pyrroles and their oxygen and sulfur analogs with quinones

Diels‐Alder reaction of 2‐(E‐2‐nitroethenyl)‐1H‐pyrrole ( 2a ) with 1,4‐benzoquinone gave the desired benzo[e]indole‐6, 9(3H)‐dione ( 4a ) in 10% yield versus a 26% yield (lit. 86% [5]) of the known N‐methyl compound ( 4b ) from the N‐(or 1)‐methyl compound ( 2b ). Protection of the nitrogen of 2a with a phenylsul‐fonyl group ( 2c ) gave a 9% yield of the corresponding N‐(or 3)‐phenylsulfonyl compound ( 4c ). The reaction of 2b with 1,4‐naphthoquinone gave in 6% yield (lit. 64% [5]) the known 3‐methylnaphtho[2,3‐e]‐indole‐6, 9(3H)‐dione ( 6 ). The reaction of 2‐(E‐2‐nitroethenyl)furan ( 8a ) gave a small yield of the desired naphtho[2,1‐b]furan‐6, 9‐dione ( 9a ), recognized by comparing its NMR spectrum with that of 4b. The corresponding reaction of 2‐(E‐2‐nitroethenyl)thiophene ( 8b ) gave a 4% yield of naphtho[2,1‐ b ]thiophene‐6,9‐dione ( 9b ), previously prepared in 24% yield [12] in a three‐step procedure involving 2‐ethenylthiophene. Introducing an electron‐releasing 2‐methyl substituent into 8a and 8b gave 12a and 12b , which, upon reaction with 1,4‐benzoquinone, gave 2‐methylnaphtho[2,1‐b]furan‐6, 9‐dione ( 13a ) and its sulfur analog ( 13b ) in yields of 4 and 8%, respectively.     

Intermolecular C—H...O and C—H...X interactions in substituted spiroacenaphthylene structures

In the three spiroacenaphthylene structures 5′′‐[(E)‐2,3‐dichlorobenzylidene]‐7′‐(2,3‐dichlorophenyl)‐1′′‐methyldispiro[acenaphthylene‐1,5′‐pyrrolo[1,2‐c][1,3]thiazole‐6′,3′′‐piperidine]‐2,4′′‐dione, C₃₅H₂₆Cl₄N₂O₂S, (I), 5′′‐[(E)‐4‐fluorobenzylidene]‐7′‐(4‐fluorophenyl)‐1′′‐methyldispiro[acenaphthylene‐1,5′‐pyrrolo[1,2‐c][1,3]thiazole‐6′,3′′‐piperidine]‐2,4′′‐dione, C₃₅H₂₈F₂N₂O₂S, (II), and 5′′‐[(E)‐4‐bromobenzylidene]‐7′‐(4‐bromophenyl)‐1′′‐methyldispiro[acenaphthylene‐1,5′‐pyrrolo[1,2‐c][1,3]thiazole‐6′,3′′‐piperidine]‐2,4′′‐dione, C₃₅H₂₈Br₂N₂O₂S, (III), the substituted aryl groups are 2,3‐dichloro‐, 4‐fluoro‐ and 4‐bromophenyl, respectively. The six‐membered piperidine ring in all three structures adopts a half‐chair conformation, the thiazolidine ring adopts a slightly twisted envelope and the pyrrolidine ring an envelope conformation; in each case, the C atom linking the rings is the flap atom. In all three structures, weak intramolecular C—H...O interactions are present. The crystal packing is stabilized through a number of intermolecular C—H...O and C—H...X interactions, where X = Cl in (I) and F or S in (II), and C—H...O interactions are observed predominantly in (III). In all three structures, molecules are linked through centrosymmetric ring motifs, further tailored through a relay of C—H...X [Cl in (I), Br in (II) and O in (III)] interactions.