1,2-Dimethylspiro[2.3]hex-1-ene by addition of cyclobutylidene to 2-butyne

The first addition of a cyclobutylidene (carbenoid) to an alkyne is reported. By C₄+Cr₂-coupling the spiro[2.3]hex-1-ene system 8 is constructed. Furthermore, cyclobutylidene adds to methylenecyclopropane, its intramolecular reaction product, to give the novel dispiro[2.1.3.0]octane 11.     

Cyclization of Terphenyl-Bisfluorenols: A Mechanistic Study of the Regioselectvity

The mechanism of the bicyclization reaction of a series of terphenyl-bisfluorenols into dispiro[fluorene-9,6′-indeno[1,2-b]fluorene-12′,9′′-fluorene] and dispiro[fluorene-9,6′-indeno[2,1-a]fluorene-12′,9′′-fluorene] is reported. Through a combined experimental and theoretical study, the different parameters that drive the regioselectivity of this cyclization reaction have been studied and are presented.     

Highly efficient and stereoselective construction of dispiro-[oxazolidine-2-thione]bisoxindoles and dispiro[imidazolidine-2-thione]bisoxindoles

An efficient and stereoselective reaction between 3-isothiocyanato oxindoles and isatins/isatinimines has been developed to afford structurally diverse dispiro[oxazolidine-2-thione]bisoxindoles and dispiro[imidazolidine-2-thione]bisoxindoles in excellent results under mild conditions. The potential of asymmetric induction by means of a chiral auxiliary was explored. The isomers are separable, and products could be isolated as single diastereomers by column chromatography. Further synthetic transformations of the reaction product were also successfully realized.     

A Facile Synthesis of Dispiro-Ring Compounds Via Telluronium Ylides

The cyclopropanation reaction of α,α′-bis (substitutedbenzylidene)cycloalkanones with telluronium ylides was studied. The products were proved to be the derivative of dispiro[2, 1, 2, 2]nonane-4-one and dispiro[2, 1, 2, 3]decane-4-one.     

Microwave induced one-pot synthesis of fluorenespiro[9.3′]-(4′-aryl)pyrrolidine/pyrrolizidine/tetrahydropyrrolo[1,2-c]thiazolespiro[2′.2″]indan-1″,3″-dione derivatives

A versatile one-pot method for the synthesis of new dispiro heterocycles is described using an intermolecular [3+2] cycloaddition reaction. The reaction gives excellent yields when carried out under solvent-free microwave irradiation.     

An InCl3 catalyzed facile one-pot synthesis of novel dispiro[cyclopent-3′-ene]bisoxindoles

An InCl₃ catalyzed efficient synthesis of novel dispiro[cyclopent-3′-ene]bisoxindoles is accomplished via a one-pot reductive cyclization of isatylidene malononitriles using the Hantzsch ester.     

Electronic and Molecular Structure of Simple 3,3′-Bicyclopropenyls. Photoelectron Spectroscopy and Model Calculations

The electronic and molecular structure of 3,3′-bicyclopropenyl ( 1 ) and its alkyl derivatives 3,3′-dirnethyl-3,3′-bicyclopropenyl ( 2 ), dispiro [2.0.2.3]nona-1,5-diene ( 3 ), dispiro[2.0.2.4]deca-1,5-diene ( 4 ), dispiro [2.0.2.5]undeca-1, 5-diene ( 5 ), and dispiro [2.0.2.6]dodeca-1, 5-diene ( 6 ) are studied by means of photoelectron spectroscopy and model calculations. Through-bond' effects in model compound 1 are analyzed in detail, illustrating a general difficulty with NDO models. Low-energy photoelectron bands of 2–6 can be assigned to ejection of electrons from cyclo-propenyl π- and Walsh-orbitals. Strong ‘through-bond’ coupling leads to splitting of the π-bands in the range 1.0–1.5 eV, while the strongly conformation-dependent splitting of the Walsh-bands allows conclusions concerning the preferred torsional angles. The preference of a gauche-conformation is predicted for 2 in the gas phase.     

Synthesis of spiro[furan-3,3′-indolin]-2′-ones by PET-catalyzed [3+2] reactions of spiro[indoline-3,2′-oxiran]-2-ones with electron-rich olefins

An efficient procedure for the synthesis of spiro[furan-3,3′-indolin]-2-ones and dispiro[cycloalkane-1,2′-furan-3′,3″-indolin]-2″-ones has been achieved in high yields and stereoselectivity by photoinduced electron transfer-catalyzed [3+2] reactions of substituted spiro[indoline-3,2′-oxiran]-2-ones with olefins. The reactions proceed by ring opening of spiro[indoline-3,2′-oxiran]-2-ones via C_β–O bond cleavage and subsequent cycloaddition with olefins by using 2,4,6-triphenylpyrylium tetarfluoroborate (TPT) as a sensitizer.     

One pot synthesis of novel dispiro[oxindole‐thiazolidinedione/thioxo‐thiazolidinone/dihydro pyrazolone]‐pyrrolidines via 1,3‐dipolar cycloaddition reaction of azomethine ylides

A series of novel dispiro[oxindole‐thiazolidinedione]pyrrolidine, dispiro[oxindole‐thioxothiazolidinone]‐pyrrolidine, dispiro[oxindole‐dihydro‐pyrazolone]pyrrolidine were synthesized by both regio‐ and stereo‐selective 1,3‐dipolar cycloaddition reaction of azomethine ylide generated from amino acid and amino acid ester with π‐deficient alkenes in a single pot protocol in good yield. X‐ ray crystallographic studies established orthogonal disposition between spiro‐oxindole and spiro‐thiazolidinedione rings in 4a and 5a .     

Regio‐ and stereospecific assembly of dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidines] from simple precursors using a one‐pot procedure: synthesis,spectroscopic and structural characterization,and a proposed mechanism of formation

The synthesis and characterization of three new dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine] compounds are reported, together with the crystal structures of two of them. (3RS,1′SR,2′SR,7a′SR)‐2′‐(4‐Chlorophenyl)‐1‐hexyl‐2′′‐sulfanylidene‐5′,6′,7′,7a′‐tetrahydro‐2′H‐dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine]‐2,4′′‐dione, C₂₈H₃₀ClN₃O₂S₂, (I), (3RS,1′SR,2′SR,7a′SR)‐2′‐(4‐chlorophenyl)‐1‐benzyl‐5‐methyl‐2′′‐sulfanylidene‐5′,6′,7′,7a′‐tetrahydro‐2′H‐dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine]‐2,4′′‐dione, C₃₀H₂₆ClN₃O₂S₂, (II), and (3RS,1′SR,2′SR,7a′SR)‐2′‐(4‐chlorophenyl)‐5‐fluoro‐2′′‐sulfanylidene‐5′,6′,7′,7a′‐tetrahydro‐2′H‐dispiro[indoline‐3,3′‐pyrrolizine‐1′,5′′‐thiazolidine]‐2,4′′‐dione, C₂₂H₁₇ClFN₃O₂S₂, (III), were each isolated as a single regioisomer using a one‐pot reaction involving l ‐proline, a substituted isatin and (Z)‐5‐(4‐chlorobenzylidene)‐2‐sulfanylidenethiazolidin‐4‐one [5‐(4‐chlorobenzylidene)rhodanine]. The compositions of (I)–(III) were established by elemental analysis, complemented by high‐resolution mass spectrometry in the case of (I); their constitutions, including the definition of the regiochemistry, were established using NMR spectroscopy, and the relative configurations at the four stereogenic centres were established using single‐crystal X‐ray structure analysis. A possible reaction mechanism for the formation of (I)–(III) is proposed, based on the detailed stereochemistry. The molecules of (I) are linked into simple chains by a single N—H…N hydrogen bond, those of (II) are linked into a chain of rings by a combination of N—H…O and C—H…S=C hydrogen bonds, and those of (III) are linked into sheets by a combination of N—H…N and N—H…S=C hydrogen bonds.     

Some azole derivative phosphoric and thiophosphoric esters

Reaction of spiro[cyclohexane-1, 2-oxazolidine] (I) with phosphorochloridic and phosphorochloridothionic acids gave the corresponding ethers. It did not prove possible to prepare derivatives containing dispiro[cyclohexane-1, 2′-oxazolidine] radicals. Reaction of 2-thio-5, 5-dimethyloxazolid-4-one with diethylphosphorochloridate led to isolation of an alkylation product. 5, 5-Dimethylhydrantoin did not react with chlorides of phosphoric acid under the reaction conditions of these particular experiments.     

Exploring the photoinduced electron transfer reactivity of aza[60]fullerene iminium cation

Photolysis of (C₅₉N)₂ solutions in the presence of neutral π-donors, such as arenes and electron-rich alkenes leads to a series of novel aza[60]fullerene monoadducts. The key step of the reaction involves a photoinduced electron transfer from the donor molecule to the iminium cation of aza[60]fullerene, followed by radical coupling of the resulting aza[60]fullerenyl radical with an intermediate stabilized radical derived from the substrate. This type of reactivity has been proven efficient with arenes having oxidation potential higher than about 1.5 V. Simple olefins, such as tri- and tetra-methylethylene, as well as cyclohexene, can also participate in this kind of photoinduced electron transfer-initiated reaction with C₅₉N⁺, affording the corresponding aza[60]fullerene derivatives. In the case of 2-methoxyprop-1-ene, 2,4-hexadiene, and β,β-dimethylstyrene, [2+2] cycloaddition reactions with the aza[60]fullerene carbon shell dominate, leading to a mixture of unidentified multiadducts.     

Novel h-shaped persistent architecture based on a dispiro building block system

[structure: see text] A novel dispiro building block, dispiro[fluorene-9,5'(7'H)-diindeno[2,1-b:1',2'-d]thiophene-7',9' '-fluorene], and its two derivatives, TBP-DSFDITF and TDOF-DSFDITF, were designed and synthesized. Because of the rigidity and orthogonality of the spiro structure, TBP-DSFDITF exhibits a well-defined H-shaped architecture, which consists of two ter(biphenyls) as the arms of the H-shape and 3,4-diphenylthiophene as the rung, connecting via completely rigid dispiro linkages with two sp(3) carbon atoms.     

Dispirofluorene-indenofluorene (DSFIF): synthesis, electrochemical, and optical properties of a promising new family of luminescent materials

[reaction: see text] A series of new dispiro[fluorene-9',6,9' ',12-indeno[1,2b]fluorenes] (DSFIFs) that combine indenofluorene (IF) and spirobifluorene (SBF) architectural specificities have been prepared. Their anodic oxidations lead to the formation of nonsoluble transparent polymers. The photophysical and electrochemical properties of these new molecules have been evaluated for further blue OLED applications.     

Highly diastereoselective synthesis of dispiro[1,4-dithiane/dithiepane]bisoxindoles via Stevens rearrangement

Synthesis of dispiro[1,4-dithianes/dithiepanes]bisoxindoles from the reaction of 3-diazo-2-oxindoles and spiro-1,3-dithiolaneoxindole or -1,3-dithianeoxindole derivatives in the presence of rhodium(II) acetate dimer as a catalyst was demonstrated under mild conditions in a highly diastereoselective manner. These dispiro-compounds were obtained via intermolecular sulfonium ylides and followed by Stevens rearrangement.     

FeCl3‐Mediated Oxidative Spirocyclization of Difluorenylidene Diarylethanes Leading to Dispiro[fluorene‐9,5′‐indeno[2,1‐a]indene‐10′,9′′‐fluorene]s

A novel FeCl₃‐mediated oxidative spirocyclization for construction of a new class of di‐spirolinked π‐conjugated molecules, dispiro[fluorene‐9,5′‐indeno[2,1‐a]indene‐10′,9′′‐fluorene]s (DSFIIFs), has been reported. The combination of FeCl₃ with FeO(OH) triggered an unprecedented double one‐electron oxidation of difluorenylidene diarylethanes to afford the corresponding dispirocycles in high yields. The highest fluorescence quantum yield was up to 0.94 in solution. This protocol is also applicable to the synthesis of the non‐spirolinked dihydroindenoindenes.     

Radical Truce-Smiles reactions on an isoxazole template: Scope and limitations

The use of TiCl₃-HCl as promotor in the radical Truce-Smiles reactions of 2-(((3,5-dimethylisoxazol-4-yl)sulfonyl)oxy)benzenediazonium salts has been investigated in detail. During these reactions the desired Truce-Smiles rearrangement (via an ipso-substitution reaction) is accompanied by the formation of a number of by-products including dihydrobenzo[5,6][1,2]oxathiino[3,4-d]isoxazole 4,4-dioxides, dioxidobenzo[e][1,2]oxathiin-3-yl)ethan-1-ones, anilines and chloroaromatics. Replacing TiCl₃-HCl by Cu(NO₃)₂-Cu₂O as reductant in these reactions was found to afford broadly comparable product distributions. Competition and radical clock experiments also provide an indication of the relative susceptibility of the isoxazole nucleus towards attack by aryl radicals.     

Synthesis of Zwitterionic Cobaltocenium Borate and Borata‐alkene Derivatives from a Borole‐Radical Anion

Chemical single‐electron reduction of 1‐mesityl‐2,3,4,5‐tetraphenylborole ( 3 ) gave a stable radical anion [CoCp*₂][ 3 ] as shown in earlier investigations. Herein, we present the reaction of [CoCp*₂][ 3 ] with the 2,2,6,6‐tetramethylpiperidine‐N‐oxyl radical (TEMPO), a common radical trap. Instead of radical recombination, the reaction proceeds through a redox pathway involving oxidation of the borole radical anion combined with reduction of TEMPO. This electron‐transfer process is accompanied by a deprotonation reaction of the cobaltocenium counterion by the base TEMPO^? to give TEMPO‐H and a neutral cobalt(I) fulvene complex ( 7 ). The latter was not observed directly during the reaction, because it instantaneously reacts as a nucleophile attacking at the boron center of the in situ generated borole 3 to give the borate 6 . However, 7 was synthesized independently by deprotonation of [CoCp*₂][PF₆]. In addition, the obtained zwitterionic cobaltocenium borate 6 undergoes a photolytic rearrangement to form the borata‐alkene derivative 9 that thermally transforms to the chiral cobaltocenium borate 12 . Our investigations are based on spectroscopic evidence, X‐ray crystallography, elemental analysis, as well as DFT calculations.     

Reverse ATRP Process of Methacrylonitrile in [C4mim][PF6]

In this original experiment, an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C₄mim][PF₆]), was used as the reaction media for reverse atom transfer radical polymerization of methacrylonitrile (MAN) initiated by azobisisobutyronitrile (AIBN) with FeCl₃ and isophthalic acid (IA) as catalyst and ligand. The polymerization in [C₄mim][PF₆] proceeded in a well-controlled manner as evidenced by kinetic studies. Compared with the polymerization in N, N-dimethylformamide (DMF), the polymerization in [C₄mim][PF₆] not only showed better control of molecular weight and narrower molecular weight distribution but also provided more rapid reaction rate with the ratio of [MAN]:[AIBN]:[FeCl₃]:[IA] at 300:1:2:4. The block copolymer PMAN-b-PSt was obtained via a conventional ATRP process in [C₄mim][PF₆] by using the resulting PMAN as macroinitiator. [C₄mim][PF₆] and FeCl₃/IA could be easily recycled and reused and had no effect on the living nature of reverse atom transfer radical polymerization of MAN.     

Bildung siliciumorganischer Verbindungen. 95. Die Kristallstruktur eines Hexadecamethyl-octasila-dispiro-[5.1.5.1]-tetradecans,Si8C22H65

Formation of Organosilicon Compounds. 95. Crystal Structure of a Hexadecamethyloctasila-dispiro [5.1.5.1]tetradecane, Si₈C₂₂H₅₆ 1,1,3,3,5,5,7,7,9,9,11,11,13,13,14,14-Hexadecamethyl-1,3,5,7,9,11,13,14-octasila-dispiro[5.1.5.1]tetradecane crystallizes monoclinically in the space group P2₁/n (No. 14) with a = 1352.4 pm, b = 1215.5 pm, c = 1001.2 pm, β = 92.11° and Z = 2 molecules per unit cell. The dispiro system is formed by a central disilacyclobutane and two C-spiro connected trisilacyclohexane rings. The symmetry of the molecule is 2/m, with flattened six membered rings in chair conformation. The Si? C bonds are enlarged (192 pm) at the strained spiro region whereas the Si? C bonds are distinctly shortened (186 pm) at the opposite Si atoms in the six membered rings.