Syntheses,Spectroscopic and DFT Studies of Two New D‐π‐A Compounds

Two novel 1,3‐dithiole‐2‐ylidene derivatives with a push–pull structures, 3‐(4,5‐dicarbomethoxy‐1,3‐dithiol‐2‐ylidene)naphthopyranone 1 and 3‐(4,5‐dimethylthio‐1,3‐dithiol‐2‐ylidene)naphthopyranone 2 , have been synthesized and characterized by ¹H NMR, IR, MS. The UV–vis spectra of 1 , 2 in CH₂Cl₂, the lowest‐energy absorption bands, are centered at 280, 316, and 430 nm for 1 and 284, 317, and 450 nm for 2 , respectively, which are caused by the HOMO → LUMO single electron promotion. Furthermore, the steady‐state fluorescence originating states of 1 , 2 from the excited charge‐transfer were observed. To estimate the position and energies of frontier orbitals for 1 , 2 , DFT calculations were performed using the Gaussian 03 program at the B3LYP/6‐31 G* level. The calculated vertical excitation energies are in good agreement with the experimental data. The high HOMO–LUMO gaps of 1 (3.08 eV) and 2 (3.00 eV) indicate high kinetic stability of the title compounds.     

无气味、实用的缩硫醛/酮化反应试剂：2-（1，3-二噻-2-亚基）-3-羰基丁酸甲酯

a-Oxo ketene dithioacetals, methyl 2-（1,3-dithian/dithiolan-2-ylidene）-3-oxobutanoate （2a/2b） prepared in nearly quantitative yields simply from methyl acetylacetate, carbon disulfide and 1,3-dibromopropane/1,2-dibromoethane in the presence of potassium carbonate, were investigated in the thioacetalization with various carbonyl compounds 3. It has been demonstrated that methyl 2-（1,3-dithian-2-ylidene）-3-oxobutanoate （2a） could act as a nonthiolic, odorless and practical thioacetalization reagent. A range of aldehydes and ketones 3 were converted into the corresponding dithioacetals 4 in high yields （up to 91%） in the presence of 2a. Moreover, 2a showed high chemoselectivity between aldehyde and ketone in thioacetalization.     

Donor‐π‐Acceptors Containing the 10‐(1,3‐Dithiol‐2‐ylidene)anthracene Unit for Dye‐Sensitized Solar Cells

Two donor–acceptor molecular tweezers incorporating the 10‐(1,3‐dithiol‐2‐ylidene)anthracene unit as donor group and two cyanoacrylic units as accepting/anchoring groups are reported as metal‐free sensitizers for dye‐sensitized solar cells. By changing the phenyl spacer with 3,4‐ethylenedioxythiophene (EDOT) units, the absorption spectrum of the sensitizer is red‐shifted with a corresponding increase in the molar absorptivity. Density functional calculations confirmed the intramolecular charge‐transfer nature of the lowest‐energy absorption bands. The new dyes are highly distorted from planarity and are bound to the TiO₂ surface through the two anchoring groups in a unidentate binding form. A power‐conversion efficiency of 3.7 % was obtained with a volatile CH₃CN‐based electrolyte, under air mass 1.5 global sunlight. Photovoltage decay transients and ATR‐FTIR measurements allowed us to understand the photovoltaic performance, as well as the surface binding, of these new sensitizers.     

Zur Hydrolyse von 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐yliden. Die Kristallstruktur von 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazoliumhydrogencarbonat

On the Hydrolysis of 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene. The Crystal Structure of 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium Bicarbonate 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium bicarbonate ( 7 ), formed on the exposure of 2,3‐dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene ( 6 ) towards air, is prepared on the reaction of 6 with ammonium bicarbonate; its crystal structure analysis reveals the presence of dimeric bicarbonate anions linked to each other and to the imidazolium ions with hydrogen bonds.     

Efficient Synthesis of 1,3‐Dithiol‐2‐one Derivatives via 4,5‐Bis(dibromomethyl)‐1,3‐dithiol‐2‐one

A series of 1,3‐dithiol‐2‐one derivatives via [4 + 2] Diels–Alder cycloaddition reaction of 4,5‐bis(dibromomethyl)‐1,3‐dithiol‐2‐one with vinyl‐substituted compounds have been synthesized. Structures of all the newly synthesized compounds are well supported by spectral data such as ¹H‐NMR, MS, and elemental analysis. The structures of IVf and IVg have been analyzed by X‐ray crystallography.     

The dithiolene ligand and tetrathiafulvalene precursor molecules 4,5‐bis(bromomethyl)‐1,3‐dithiol‐2‐one and 4,5‐bis[(dihydroxyphosphoryl)methyl]‐1,3‐dithiol‐2‐one

The crystal structures of 4,5‐bis(bromomethyl)‐1,3‐dithiol‐2‐one, C₅H₄Br₂OS₂, (I), and 4,5‐bis[(dihydroxyphosphoryl)methyl]‐1,3‐dithiol‐2‐one, C₅H₈O₇P₂S₂, (II), occur with similar unit cells in the same monoclinic space group. Both molecules reside on a twofold symmetry axis coincident with the C=O bond, so that the substituents in the 4‐ and 5‐positions project above and below the plane of the 1,3‐dithiol‐2‐one ring. In both structures, the molecules align themselves in a head‐to‐tail fashion along the b axis, and these rows of molecules then stack, with alternating directionality, along the c axis. For (II), an extensive network of intermolecular hydrogen bonds occurs between molecules within the same stack and between adjacent stacks. Each –CH₂P(O)(OH)₂ group participates in four hydrogen bonds, twice as donor and twice as acceptor.     

n‐Channel Organic Transistors Processed from Halogen‐Free Solvents: Solvent Effect on Thin‐Film Morphology and Charge Transport

Non‐chlorinated solvents are highly preferable for organic electronic processing due to their environmentally friendly characteristics. Four different halogen‐free solvents, tetrafuran, toluene, meta‐xylene and 1,2,4‐trimethylbenzene, were selected to fabricate n‐channel organic thin film transistors (OTFTs) based on 3‐hexylundecyl substituted naphthalene diimides fused with (1,3‐dithiol‐2‐ylidene)malononitrile groups (NDI3HU‐DTYM2). The OTFTs based on NDI3HU‐DTYM2 showed electron mobility of up to 1.37 cm²·V^?1·s^?1 under ambient condition. This is among the highest device performance for n‐channel OTFTs processed from halogen‐free solvents. The different thin‐film morphologies, from featureless low crystalline morphology to well‐aligned nanofibres, have a great effect on the device performance. These results might shed some light on solvent selection and the resulting solution process for organic electronic devices.     

Reactions of 2‐(1,3‐Dithiolan‐2‐ylidene)malononitrile with Amino‐ and Hydrazinophosphorus Compounds: A Facile Route to Functionalized Phosphorus Heterocycles

A facile and efficient route to functionalized phosphorus heterocycles was achieved by treatment of 2‐(1,3‐dithiolan‐2‐ylidene)malononitrile with amino‐ and hydrazinophosphorus compounds in the presence of a strong base via fragmentation of 1,3‐dithiolane ring.     

Metalla‐Assembled Electron‐Rich Tweezers: Redox‐Controlled Guest Release Through Supramolecular Dimerization

Developing methodologies for on‐demand control of the release of a molecular guest requires the rational design of stimuli‐responsive hosts with functional cavities. While a substantial number of responsive metallacages have already been described, the case of coordination‐tweezers has been less explored. Herein, we report the first example of a redox‐triggered guest release from a metalla‐assembled tweezer. This tweezer incorporates two redox‐active panels constructed from the electron‐rich 9‐(1,3‐dithiol‐2‐ylidene)fluorene unit that are facing each other. It dimerizes spontaneously in solution and the resulting interpenetrated supramolecular structure can dissociate in the presence of an electron‐poor planar unit, forming a 1:1 host–guest complex. This complex dissociates upon tweezer oxidation/dimerization, offering an original redox‐triggered molecular delivery pathway.     

Unexpected Ritter Reaction During Acid‐Promoted 1,3‐Dithiol‐2‐one Formation

A series of aryl‐substituted 1,3‐dithiol‐2‐ones was prepared by the Bhattacharya? Hortmann cyclization method. Unexpectedly, a Ritter reaction occurred during the acid‐catalyzed cyclization at the cyano group of the aryl substituents and 1,3‐dithiol‐2‐ones bearing a carboxy or a carboxamide group could be selectively obtained (see 1 and 2a in Scheme 1). The formation of the acid or the amide functionality was temperature‐dependent so that the one or the other group could be introduced selectively by modifying the reaction temperature.     

Diastereoselective Synthesis of (Z)‐6‐(2‐Oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐diones

Two efficient and diastereoselective procedures for the synthesis of (Z)‐6‐(2‐oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐diones by aldol‐crotonic condensation of 1,3‐dimethyl‐3a,9a‐diphenyl‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐dione with isatins under acidic or basic catalysis are reported. Isomerization in (Z)‐7‐(1‐allyl‐2‐oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐1,3‐dimethyl‐3a,9a‐diphenyl‐1,3a,4,9a‐tetrahydroimidazo[4,5‐e]thiazolo[2,3‐c]‐1,2,4‐triazin‐2,8(3H,7H)‐dione was observed under basic conditions.     

New domino‐reaction for the synthesis of N4‐(5‐aryl‐1,3‐oxathiol‐2‐yliden)‐2‐phenylquinazolin‐4‐amines and 4‐[4‐aryl‐5‐(2‐phenylquinazolin‐4‐yl)‐1,3‐thiazol‐2‐yl]morpholine

The model morpholine‐1‐carbothioic acid (2‐phenyl‐3H‐quinazolin‐4‐ylidene) amide (1) reacts with phenacyl bromides to afford N⁴‐(5‐aryl‐1,3‐oxathiol‐2‐yliden)‐2‐phenylquinazolin‐4‐amines (4) or N⁴‐(4,5‐diphenyl‐1,3‐oxathiol‐2‐yliden)‐2‐phenyl‐4‐aminoquinazoline ( 5 ) by a thermodynamically controlled reversible reaction favoring the enolate intermediate, while the 4‐[4‐aryl‐5‐(2‐phenylquinazolin‐4‐yl)‐1,3‐thiazol‐2‐yl]morpholine ( 8 ) was produced by a kinetically controlled reaction favoring the C‐anion intermediate. ¹H nmr, ¹³C nmr, ir, mass spectroscopy and x‐ray identified compounds ( 4 ), ( 5 ) and ( 8 ).     

Reaction of cyclic imidates with α,β‐unsaturated esters: Synthesis of new pyrrolo[2,1‐b]‐1,3‐oxazine and pyrido[2,1‐b]‐1,3‐oxazine derivatives

The cycloaddition reaction of cyclic imidates, 2‐benzyl‐5,6‐dihydro‐4H‐1,3‐oxazines 1a , 1b , 1c , 1d , 1e , 1f , with dimethyl acetylenedicarboxylate 2 , trimethyl ethylenetricarboxylate 4 , or dimethyl 2‐(methoxymethylene)malonate 6 afforded new fused heterocyclic compounds, such as methyl (6‐oxo‐3,4‐dihydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐ylidene)acetates 3a , 3b , 3c , 3d , 3e , 3f (71–79%), dimethyl 2‐(6‐oxo‐3,4,6,7‐tetrahydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐yl)malonates 5b , 5c , 5d , 5e , 5f (43–71%), or methyl 6‐oxo‐3,4‐dihydro‐2H,6H‐pyrido[2,1‐b]‐1,3‐oxazine‐7‐carboxylates 7a , 7b , 7c , 7d , 7e , 7f (32–59%), respectively. In these reactions, 1a , 1b , 1c , 1d , 1e , 1f (cyclic imidates, iminoethers) functioned as their N,C‐tautomers (enaminoethers) 2 to α,β‐unsaturated esters 2 , 4, and 6 to give annulation products 3 , 5 , and 7 following to the elimination of methanol, respectively. J. Heterocyclic Chem., (2011).     

Potassium Thiocyanate‐Promoted One‐Pot Synthesis of (1,3‐Diaryl‐2,5‐dioxoimidazolidin‐4‐ylidene)acetates from Aryl Isocyanates and Alkyl Propiolates. Short Communication

The reaction of aryl isocyanates and alkyl propiolates (=alkyl prop‐2‐ynoates) in the presence of potassium thiocyanate (KSCN) led to geometric isomers of alkyl 2‐(1,3‐diaryl‐2,5‐dioxoimidazolidin‐4‐ylidene)acetates in moderate‐to‐good yields.     

4‐(9,10‐Dihydroacridin‐9‐ylidene)thiosemicarbazide and its five‐membered thiazole and six‐membered thiazine derivatives

Two methyl derivatives, five‐membered methyl 2‐{2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4‐oxo‐4,5‐dihydro‐1,3‐thiazol‐5‐ylidene}acetate, C₂₀H₁₆N₄O₃S, (I), and six‐membered 2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4H‐1,3‐thiazin‐4‐one, C₁₈H₁₄N₄OS, (II), were prepared by the reaction of the N‐methyl derivative of 4‐(9,10‐dihydroacridin‐9‐ylidene)thiosemicarbazide, C₁₄H₁₂N₄S, (III), with dimethyl acetylenedicarboxylate and methyl propiolate, respectively. The crystal structures of (I), (II) and (III) are molecular and can be considered in two parts: (i) the nearly planar acridine moiety and (ii) the singular heterocyclic ring portion [thiazolidine for (I) and thiazine for (II)] including the linking amine and imine N atoms and the methyl C atom, or the full side chain in the case of (III). The structures of (I) and (II) are stabilized by N—H...O hydrogen bonds and different π–π interactions between acridine moieties and thiazolidine and thiazine rings, respectively.     

Synthesis of novel palladium N‐heterocyclic‐carbene complexes as catalysts for Heck and Suzuki cross‐coupling reactions

Novel palladium‐1,3‐dialkylperhydrobenzimidazolin‐2‐ylidene (2a–c) and palladium‐1,3‐dialkylimidazolin‐2‐ylidene complexes (4a,b) have been prepared and characterized by C, H, N analysis, ¹H‐NMR and ¹³C‐NMR. Styrene or phenylboronic acid reacts with aryl halide derivatives in the presence of catalytic amounts of the new palladium‐carbene complexes, PdCl₂(1,3‐dialkylperhydrobenzimidazolin‐2‐ylidene) or PdCl₂(1,3‐dialkylimidazolin‐2‐ylidene) to give the corresponding C? C coupling products in good yields. Copyright © 2006 John Wiley & Sons, Ltd.     

Reactions of 2‐Unsubstituted 1H‐Imidazole 3‐Oxides with 2,2‐Bis(trifluoromethyl)ethene‐1,1‐dicarbonitrile: A Stepwise 1,3‐Dipolar Cycloaddition

The reaction of 1,4,5‐trisubstituted 1H‐imidazole‐3‐oxides 1 with 2,2‐bis(trifluoromethyl)ethene‐1,1‐dicarbonitrile ( 7 , BTF) yielded the corresponding 1,3‐dihydro‐2H‐imidazol‐2‐ones 10 and 2‐(1,3‐dihydro‐2H‐imidazol‐2‐ylidene)malononitriles 11 , respectively, depending on the solvent used. In one example, a 1 : 1 complex, 12 , of the 1H‐imidazole 3‐oxide and hexafluoroacetone hydrate was isolated as a second product. The formation of the products is explained by a stepwise 1,3‐dipolar cycloaddition and subsequent fragmentation. The structures of 11d and 12 were established by X‐ray crystallography.     

Synthese und Charakterisierung von Cobalt(II)‐ und Kupfer(I)‐Komplexen mit Guanidin‐Pyridin‐Hybridliganden

Syntheses and Structures of Cobalt(II) and Copper(I) Complexes with Guanidine‐Pyridine Hybridligands The guanidine‐pyridine hybridligands N‐(1,3‐dimethylimidazolidin‐2‐ylidene)‐2‐(pyridine‐2‐yl)ethanamine (DMEGepy, L1 ) and 1,1,3,3‐tetramethyl‐2‐(2‐(pyridine‐2‐yl)ethyl)guanidine (TMGepy, L2 ) have been synthesized and characterized. The reaction of DMEGepy with CoCl₂ and TMGepy with CuI lead to the mononuclear complexes {N‐(1,3‐dimethylimidazolidin‐2‐ylidene)‐2‐(pyridine‐2‐yl)ethanamine}cobalt(II) dichloride ( 1 ) and {1,1,3,3‐tetramethyl‐2‐(2‐(pyridine‐2‐yl)ethyl)guanidine}copper(I) iodide ( 2 ). By the characterization of these complexes we are able to compare the complexation chemistry of the hybridguanidine and bisguanidine ligands with regard to the various N donor functions systematically.     

Synthesis and Structures of Arene Ruthenium (II)–NHC Complexes: Efficient Catalytic α‐alkylation of ketones via Hydrogen Auto Transfer Reaction

A panel of six new arene Ru (II)‐NHC complexes 2a‐f , (NHC = 1,3‐diethyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1a , 1,3‐dicyclohexylmethyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1b and 1,3‐dibenzyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1c ) were synthesized from the transmetallation reaction of Ag‐NHC with [(η⁶‐arene)RuCl₂]₂ and characterized. The ruthenium (II)‐NHC complexes 2a‐f were developed as effective catalysts for α‐alkylation of ketones and synthesis of bioactive quinoline using primary/amino alcohols as coupling partners respectively. The reactions were performed with 0.5 mol% catalyst load in 8 h under aerobic condition and the maximum yield was up to 96%. Besides, the different alkyl wingtips on NHC and arene moieties were studied to differentiate the catalytic robustness of the complexes in the transformations.     

Synthese und Eigenschaften von [Ph2(Carb)P]AlCl4 (Carb = 2,3‐Dihydro‐1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐yliden) – ein stabiler Carben‐Komplex des dreiwertigen Phosphors [1]

Synthesis and Properties of [Ph₂(Carb)P]AlCl₄ (Carb = 2,3‐Dihydro‐1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) – a Stable Carbene Complex of Trivalent Phosphorus [1] 2,3‐Dihydro‐1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene ( 7 , Carb) reacts with chlorodiphenylphosphane to give the cationic phosphane [Ph₂(Carb)P]Cl ( 10 ) which is transferred to the more stable salt [Ph₂(Carb)]AlCl₄ ( 13 ) on treatment with AlCl₃. The cationic phosphane selenide [Ph₂(Carb)PSe]AlCl₄ ( 14 ) is obtained from 13 and selenium. Spectroscopic and structural data indicate [Ph₂(Carb)P]⁺ to be a cationic analogue of Ph₃P. The X‐ray structure of 13 is reported.