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In the presence of Ni(dppe)Br(2) and Zn powder in acetonitrile at 80 degrees C, oxa-bicyclic olefins undergo cyclization with o-iodobenzoate and with beta-iodo-(Z)-propenoates to give the benzocoumarin derivatives in moderate to good yields. This methodology offers a simple efficient way for the synthesis of structurally complicate coumarins in one pot. [reaction: see text]

A new method for the synthesis of substituted 2-acylallylmetal reagents in a highly regio- and stereoselective fashion involving a three-component assembly of allenes, acyl chlorides, and bimetallic reagents (B-B, Si-Si, and Sn-Sn) catalyzed by phosphine-free palladium complexes is described. Treatment of various allenes (CR(2)R(3)=C=CH(2)) with acyl chlorides (R(1)COCl) and bispinacolatodiboron in the presence of PdCl(2)(CH(3)CN)(2) in toluene at 80 degrees C gave 2-acylallylboronates in moderate to good yields. The acylsilation of allenes with acid chlorides and hexamethyldisilane (5) proceeded successfully in the presence of Pd(dba)(2) in CH(3)CN affording the corresponding allylsilanes (CR(2)R(3)=C(COR(1))CH(2)SiMe(3)) in good to moderate yields. Several chloroformates (R(4)OCOCl) also react with 1,1-dimethylallene (2a) and 5 to afford allylsilanes (CR(2)R(3)=C(COOR(4))CH(2)SiMe(3)) in 66-70% yields. Acylstannation of allenes could also be achieved by slow addition of hexabutylditin (10) to the reaction mixture of acyl chloride (or chloroformate) and allene 2a in CH(3)CN in the presence of Pd(dba)(2) at 60 degrees C; the corresponding 2-substituted allylstannanes were isolated in moderate to good yields. The above catalytic reactions are completely regioselective and highly stereoselective. A mechanism is proposed to account for the catalytic reactions and the stereochemistry.

Several substituted phenanthrolines (L = pyrazino[2,3-f][1,10]phenanthroline (PyPhen), 2-methylpyrazino[2,3-f][1,10]phenanthroline (MPP), dipyrido[3,2-a:2′,3′-c]phenazine (DPPz), 11-methyldipyrido[3,2-a:2′,3′-c]phenazine (MDPz), 11,12-dimethyldipyrido[3,2-a:2′,3′-c]phenazine (DDPz), and benzo[i]dipyrido[3,2-a:2,3-c]phenazine (BDPz)) were successfully prepared and europium complexes Eu(TTA)3L (Eu-L) based on these ligands were synthesized from EuCl3, 2-thenoyltrifluoroacetone (TTA) and L in good yields. Irradiation at the absorption band between 320–390 nm of all these europium complexes, except Eu-BDPz, in solution or in the solid state leads to the emission of a sharp red band at ∼ 612 nm, a characteristic Eu3+ emission due to the transition 5D0 7F2. No emission from the ligands was found. The result indicates that complete energy transfer from the ligand to the center Eu3+ ion occurs for these europium complexes. In contrast, the photoluminescence spectrum of Eu-BDPz exhibits a strong emission at around 550 nm from the coordinated BDPz ligand and a weak emission at 612 nm from the central europium ion. Incomplete energy transfer from the ligand to the central Eu3+ ion was observed for the first time. Several electroluminescent devices (A–I) using Eu-PyPhen, Eu-MPP, Eu-DPPz, and Eu-DDPz as dopant emitters with the device configuration: TPD or NPB (50 nm)/Eu:CBP (1.7–7 %, 30 nm)/BCP (20–30 nm)/Alq (25–35 nm) (where TPD: 4,4′-bis[N-(p-tolyl)-N-phenylamino]biphenyl; NPB: 4,4′-bis[1-naphthylphenylamino]biphenyl; CBP: 4,4′-N,N′-dicarbazole biphenyl; BCP: 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; Alq: tris[8-hydroxyquinoline]aluminum) were fabricated. Some of these devices emit saturated red light and are the only europium complex-based devices that show a brightness of more than 1000 cd m–2.

Two small non-aromatic organic molecules, 1,2,3,4,5,6,7,8,9,10-decahydro-1,8-acridinedione (DAD) and 3,3,6,6-tetramethyl-1,2,3,4,5,6,7,8,9,10-decahydro-1,8-acridinedione (TDAD) were synthesized and used as blue light-emitting dopants in organic electroluminescent devices. A general device structure, ITO/NPB (20 nm)/CBP (20 nm)/DAD:TPBI (X%, Y nm)/TPBI (Z nm)/Mg:Ag (10:1; 55 nm)/Ag (100 nm) was employed for this study, where NPB, CBP and TPBI stand for 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl, 4,4′-dicarbazolyl-1,1′-biphenyl and 2,2′,2″-(1,3,5-phenylene)tris-[1-phenyl-1H-benzimidazole], respectively. Efficient blue emission with excellent Commission Internationale de L’Eclairage (CIE) coordinates (X=0.15, Y=0.08) and maximum luminance >1000 cd/m2 were obtained from the devices. The performances of the devices depend greatly on the dopant concentration and thickness of the emitting layer.

7-Oxabenzonorbornadienes derivatives la-d underwent reductive coupling with alkyl propiolates CH 3 C≡CCO 2 CH 3 (2 a), PhC≡CCO 2 Et (2b), CH 3 (CH 2 ) 3 C≡CCO 2 CH 3 (2 c), CH 3 (CH 2 ) 4 C≡CCO 2 CH 3 (2d), TMSC≡ CCO 2 Et (2e), (CH 3 ) 3 C≡CCO 2 CH 3 (2 f) and HC≡CCO 2 Et (2g) in the presence of [NiBr 2 (dppe)] (dppe = Ph 2 PCH 2 CH 2 PPh 2 ), H 2 O and zinc powder in acetonitrile at room temperature to afford the corresponding 2-alkenyl-1,2-dihydronapthalen-1-ol derivatives 3 a - n with remarkable regio- and diastereoselectivity in good to excellent yields. Similarly, the reaction of 7-azabenzonorbornadienes derivative 1e with propiolates 2a, b and d proceeded smoothly to afford reductive coupling products 2-alkenyl-1,2-dihydronapthalene carbamates 3o-p in good yields with high regio- and stereoselectivity. This nickel-catalyzed reductive coupling can be further extended to the reaction of 7-oxabenzonorbornene derivatives. Thus, 5,6-di(methoxymethyl)-7-oxabicydo[2.2.1]hept-2-ene (4) reacted with 2a and 2d to furnish cyclohexenol derivatives bearing four cis substituents 5 a and b in 81 and 84% yield, respectively. In contrast to the results of 4 with 2, the reaction of dimethyl 7-oxabicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylate (6) with propiolates 2a-d afforded the corresponding reductive coupling/cyclization products, bicyclo[3.2.1]γ-lactones 7a-d in good yields. The reaction provides a convenient one-pot synthesis of γ-lactones with remarkably high regio- and stereoselectivity.

An efficient method for the preparation of various monosubstituted arylallenes, disubstituted allenes and alkenylallenes via palladium-catalyzed coupling of allenylstannanes with aryl iodides or alkenyl iodides is described. The coupling reaction was carried out in the presence of Pd(PPh 3 ) 4 and LiCl using DMF as solvent. The possible role of LiCl in this coupling process is discussed based on the 119 Sn NMR studies.

A novel acid-catalyzed ring expansion of methanofullerenes bearing an alpha-ylidic ester has been investigated. Treatment of dialkyl acetylenedicarboxylate and tricycloalkylphosphine with C(60) led to the isolation of a methanofullerene ylide after passing the reaction mixtures through a basic alumina column. If the reaction mixture was passed through a silica gel column, a cyclopentanofullerene was isolated instead. These new cyclopentanofullerenes consisted of a fused cyclopentanone ring bearing an alpha-hydroxy ester and a phosphonium ylide and were confirmed by their NMR, mass, and X-ray diffraction data. The cyclopentanofullerenes were formed by the ring expansion of the corresponding methanofullerenes in the presence of silica gel. The ring expansion also proceeded by treating methanofullerene with acetic acid in chloroform. On the other hand, the methanofullerenes from RO(2)CCCCO(2)R, PAr(3), and C(60) were stable in silica gel. However, upon heating with acetic acid at 50 degrees C, they underwent ring expansion and dephosphination to give cyclopentenofullerenes. An implicit vinyl cyclopropane ring expansion mechanism was proposed to account for this novel acid-catalyzed rearrangement.

Diaminoanthracene derivatives 9,10-bis(1-naphthylphenylamino)anthracene (α-NPA), 9,10-bis(2-naphthylphenylamino)anthracene (β-NPA), 9,10-bis(m-tolylphenylamino)anthracene (TPA), and 9,10-bis(diphen...

In this study, a novel perovskite quantum dot (QD) spray-synthesis method is developed by combining traditional perovskite QD synthesis with the technique of spray pyrolysis. By utilizing this new technique, the synthesis of cubic-shaped perovskite QDs with a homogeneous size of 14 nm is demonstrated, which shows an unprecedented stable absolute photoluminescence quantum yield ≈100% in the solution and even in the solid-state neat film. The highly emissive thin films are integrated with light emission devices (LEDs) and organic light emission displays (OLEDs). The color conversion type QD-LED (ccQD-LED) hybrid devices exhibit an extremely saturated green emission, excellent external quantum efficiency of 28.1%, power efficiency of 121 lm W-1 , and extraordinary forward-direction luminescence of 8 500 000 cd m-2 . The conceptual ccQD-OLED hybrid display also successfully demonstrates high-definition still images and moving pictures with a 119% National Television System Committee 1931 color gamut and 123% Digital Cinema Initiatives-P3 color gamut. These very-stable, ultra-bright perovskite QDs have the properties necessary for a variety of useful applications in optoelectronics.

[reaction: see text] Effective nickel-catalyzed cocycloaddition of nonconjugated diynes with conjugated diynes yields polysubstituted arylalkynes in good to excellent yields with high regio- and chemoselectivity.

In this article, new metal-mediated cyclization and reductive coupling reactions of bicyclic olefins with alkynes are described. Oxabicyclic alkenes undergo cyclization with alkyl propiolates at 80 C catalyzed by nickel complexes to give benzocoumarin derivatives in high yields. The reaction of bicyclic alkenes (oxa- and azacyclic alkenes) with alkyl propiolates at room temperature in the presence of the same nickel complex gave 1,2-dihydro-napthelene derivatives in good-to-excellent yields. This reductive coupling reaction proceeds under very mild conditions in complete regio- and stereoselective fashion. A mechanism to account for the coumarin formation and the reductive coupling is proposed.

A CoI(2)/(R)-BINAP, Zn, ZnI(2), H(2)O system efficiently catalyzes the intermolecular asymmetric reductive coupling of alkynes with cyclic enones to afford highly regio- and enantioselective β-alkenyl cyclic ketones. A possible mechanism that involves the formation of a cobaltacyclopentene intermediate from the alkyne and cyclic enone is proposed.

A nickel-catalyzed regio- and stereoselective reductive coupling of oxa- and azabicyclic alkenes with activated alkenes and electron-rich alkynes is described. Thus, 7-oxabenzonorbornadienes underwent reductive coupling with various vinyl ketones such as ethyl, methyl, propyl and alpha-methyl-substituted vinyl ketones, in the presence of a nickel(II) iodide (NiI2), zinc (Zn), and water catalyst system in acetonitrile at 50 degrees C for 14 h to afford 2-alkylnaphthalenes in good to excellent yields. Under similar reaction conditions, 7-azabenzonorbornadiene derivatives provided cis-2-alkyl-1,2-dihydro-naphthalene derivatives in high yields. On the other hand, the nickel(II) iodide, tris(4-fluorophenyl)phoshine [P(4-FC6H4)(3)] and zinc catalyst system successfully catalyzed the reductive coupling reaction of electron-rich alkynes, with 7-aza- and 7-oxabenzonorbornadienes to give cis-2-alkenyl-1,2-dihydronaphthalene derivatives in good to excellent yields. In the reaction, a mild reducing agent (zinc) and simple hydrogen source (water) were used.

A nickel-catalyzed, highly regioselective conjugate addition of boronic acids to dienones to form 1,4-addition products with an all-carbon quaternary center is described.

The highly regioselective synthesis of unprotected indoles involves the reaction of the hydrochloride substrates with diethyl ketone to form hydrazones.

The target compounds can be obtained from the premade imines or imines, generated in situ from anilines and aldehydes, with arenes.

Moreover, the intramolecular reductive coupling of ene-phthalimide (XI) proceeds highly diastereoselective.

A nickel-catalyzed highly regioselective 1,4-addition reaction of boronic acids to dienones to form products with an all-carbon quaternary center is described. The 3-alkenyl group of dienones is the key for the reaction to proceed smoothly. A mechanism involving the coordination of the dienyl group to the nickel center is proposed.

Metal-catalyzed annulation reactions to synthesize carbo- and heterocycles have been an attractive field of research for many years. The development of new cyclization reactions utilizing readily available less expensive metal catalyst is one of the important tasks. In this regard, this review summerizes and discusses about nickel- and cobalt-catalyzed [4+2] and [3+2] annulation reactions of ortho-halo substituted imines and alkynes. Nickel complexes under suitable reaction conditions underwent [4+2] annulation to form six-membered isoquinoline (salts) derivatives. However, cobalt complexes afforded aminoindenes via [3+2] annulation reactions. Both reactions proceed through a five membered metallacycle. The regioselective insertion of alkyne containing keto or ester groups into the metallacycle further demonstrates the difference in selectivity of these metal complexes.

The presented oxidative carbonylation of 2-arylphenols proceeds under acid-base free and mild conditions with a variety of substrates.

An efficient method for the synthesis of highly substituted isoquinolines by a Rh(III)-catalyzed hydrazone directed ortho C—H bond activation and annulation without an external oxidant is described.

A convenient, mild, and efficient method for the synthesis of a broad range of substituted isoquinolinium salts from pyridines and alkynes is presented.

The one-pot synthesis of substituted phenanthridinones involves a rhodium-catalyzed dual C—H bond activation and annulation reactions.

Discover nickel! A nickel-catalyzed alkenylative cyclization of 1,6-enynes and alkenyl boronic acids affording substituted pyrrolidines and dihydrofurans is described (see scheme; cod = 1,5-cyclooctadiene, Ts = p-toluene sulfonate). The reaction is highly chemo- and stereoselective. A possible reaction mechanism involving a nickelacyclopentene intermediate is proposed.

2-Aminoaryl methyl ketones undergo intramolecular oxidative C–H amination to give the corresponding substituted isatins under an oxygen atmosphere in the presence of [CuI(bpy)]2.

An efficient synthesis of quinolizinium salts from 2-vinylpyridines and alkynes via Rh(III) or Ru(II)-catalyzed C–H activation and annulation reaction is described. A possible mechanism involving pyridine assisted vinylic ortho-C–H activation, alkyne insertion and reductive elimination is proposed.

This chapter deals with developments in the [2+2] cycloaddition of organic molecules containing π-bonds that are catalyzed by various transition metal complexes. Significant progress has been made in this field over the past several decades. Transition metals such as Ru, Co, Ni, Rh, Pd, Au, Cu, Pt, Ir, and In are utilized as catalysts in the synthesis of various highly substituted cyclobutenes or cyclobutanes, azetidines, β-lactams, and oxetenes. Mechanistically, most of the reactions proceed via the formation of metallacyclopentenes or metallacyclopentanes as key intermediates followed by reductive elimination. The mechanistic aspects of the [2+2] cycloaddition, the substrate scope, the limitations of the reaction, and the synthetic applications are discussed. In addition, some asymmetric variants of these reactions are also presented. Four-membered ring products are very versatile synthetic units for the synthesis of both acyclic and cyclic systems, including carbo- and heterobicyclic compounds, and some of these applications are also shown.

[60]Fullerene derivative 1 containing of an α-ylide group exists as a mixture of E and Z isomers. Treatment of 1 with MgBr2 or LiI in CDCl3 under ultrasonic agitation gave an adduct in which the carbonyl oxygen of α-ylide ester moiety in 1 is coordinated to the metal ion. The NMR spectra show that the adducts exist as a single isomeric form. After ultrasonic agitation, the adducts gradually revert to the original E,Z-mixture owing to slow absorption of moisture. Further ultrasonic treatment of the mixture resumes the complexation as long as enough anhydrous metal halides are still present.

Treatment of various 1,4-epoxy-1,4-dihydroarenes with trichlorosilane in toluene in the presence of a palladium complex affords the corresponding biaryls in good to excellent yields. The process appears to occur via a novel palladium-catalyzed hydrosilylative dimerization of 1,4-epoxy-1,4-dihydroarenes and subsequent elimination of HOSiCl(3) and H(2)O.

A palladium-catalyzed chelation-assisted C-H activation of alkyl aryl ketones and their reaction with aryl iodides to afford ortho-arylated products is described. For sec-alkyl aryl ketones, the catalytic reaction proceeds further to give 10,10-dialkylphenanthrone derivatives. A possible reaction mechanism involving directed dual C-H bond activation and enolate cyclization for the formation of 10,10-dialkylphenanthrone derivatives is proposed.

[reaction: see text] Highly regio- and stereoselective allylation of aldehydes by allenes proceeds smoothly in aqueous/organic media in the presence of PdCl(2)(PPh(3))(2), HCl, and SnCl(2). The reaction likely occurs via hydrostannylation of allenes and allylation of aldehydes by the in situ generated allyltrichlorotins to afford the final products.

The reentrant behavior of Poly(vinyl alcohol) (PVA)–borax aqueous semidilute solutions with a PVA concentration of 20 g/l and borax concentrations varies from 0.0 to 0.20 M was investigated using dynamic light scattering (DLS) and dynamic viscoelastic measurements. Two (fast and slow modes) and three (fast, middle, and slow) relaxation modes of PVA semidilute aqueous solutions without and with the presence of borax, respectively, were observed from DLS measurements. The fast and middle relaxation modes were q2-dependent (q is the scattering vector) characteristic of diffusive behavior; however, the slow modes were q3-dependent, characteristic of intraparticle dynamics. The experimental results showed that the slow relaxation mode dominates the DLS relaxation. The DLS slow mode relaxation time, τs, and the viscoelastic modulus G′(ω) and G′′(ω) data had a similar trend and demonstrated reentrant behavior as the borax concentration was increased from 0.0 to 0.20 M, i.e. τs, G′(ω), and G′′(ω) fluctuated with increasing borax concentration. The excluded-volume effect of polymers, charge repulsion among borate ions bound on PVA molecules, and intermolecular cross-linking didiol–borate complexation caused an expansion of the polymer chain; however, the screening effect of free Na+ ions on the negative charge of the borate ions bound on PVA and intramolecular cross-linking didiol–borate complexation led to a shrinkage of the polymer chain. The reentrant behavior was the consequence of the balance between expansion and shrinkage of the PVA–borate complex.

A wide range of aryl and vinylic halides react with 1,1-dimethylallene (2a) and potassium carbonate in the presence of Pd(dba)(2) (dba = dibenzylideneacetone) in N,N-dimethylacetamide (DMA) at temperature 100-120 degrees C to give the corresponding dienes CH(2)C(CH(3))CRCH(2) (3a-o), where R is aryl or vinylic, in good to excellent yields. Higher yields of diene products were obtained for aryl bromides than for the corresponding aryl iodides and chlorides. Under similar reaction conditions, tetramethylallene (2b), 1-methyl-1-phenylallene (2c), 1-methyl-3-phenylallene (2d), and 1-cyclohexylallene (2e) also react with aryl and vinylic halides to give diene products (3p-w). For 2d, both E and Z isomers 3t and 3u of the diene product were observed. For 2e, two regioisomers 3vand 3w were isolated with 3w likely from alkene isomerization of 3v. Various palladium systems were tested for the catalytic activity of diene formation. In addition to Pd(dba)(2)/PPh(3), Pd(OAc)(2)/PPh(3), PdCl(2)(PPh(3))(2), and PdCl(2)(dppe) are also very effective as catalysts for the reaction of 2a with p-bromoacetophenone (1a) to give 3a. Studies on the effect of solvents and bases show that DMA and K(2)CO(3) are the solvent and base that give the highest yield of diene 3a. Possible mechanisms for this catalytic diene formation are proposed.

Oxabenzonorbornadiene (1a) reacted with various alkynes in the presence of Ni(PPh3)2Cl2, PPh3 and zinc powder in toluene to give two common products 2a and 2b regardless of the alkyne used. The formation of 2a and 2b are proposed to be from the Diels–Alder reaction of 1a and isobenzofuran. The latter is generated from the retro Diels–Alder reaction of [2 + 2 + 2] cycloadducts of 1a and alkynes catalyzed by the nickel system. A series of nickel-catalyzed [2 + 2 + 2] cycloadducts (4a–j and 5a–d) of oxa- and azabenzonorbornadienes (1a–d) with terminal alkynes were isolated at temperatures −5–18 °C. Similarly, hepta-1,6-diyne and octa-1,7-diyne reacted with 1a and 1d to give novel pentacyclic [2 + 2 + 2] cycloadducts 6a–d in 62–75% yields. These products are convenient isobenzofuran and isoindole precursors that react with various dienophiles to afford the corresponding Diels–Alder adducts. In addition, the [2 + 2 + 2] cycloadducts may be used as precursors for the synthesis of aromatic compounds. For example, the reaction of 1a with methyl but-2-ynoate catalyzed by the nickel system provided aromatic compound 3 in 94% yield. In this reaction, 1a is a ‘masked acetylene’ providing an acetylene moiety to 3.

A new method for the synthesis of highly substituted allyl azides by carboazidation of allenes catalyzed by palladium complexes is described. Treatment of 1,1-dimethylallene (1a) with an aromatic iodide ArI 2 (4-CH3COC6H4I, 4-CH3OC6H4I, 3-CH3OC6H4I, 4-CH3C6H4I, 3-CH3C6H4I, 3-C2H5OCOC6H4I, 4-C2H5OCOC6H4I, 4-ClC6H4I, 3-BrC6H4I or 1-iodothiophene), (CH3)3SiN3 and KOAc in the presence of Pd(dba)2 (dba = dibenzylideneacetone) in DMF at 70 °C gave two regioisomers (CH3)2CC(Ar)CH2N33 and (CH3)2(N3)CC(Ar)CH24 in good to excellent yields. The observed regio- and stereoisomer ratios of the allyl azides from these reactions are close to the equilibrium ratio of these isomers at ambient temperature due to a rapid 1,3-shift of the azido group. Reduction of a mixture of 3a and 4a (80∶20, Ar = 4-C6H4COMe) by PPh3–H2O afforded only the sterically less hindered (CH3)2CC(Ar)CH2NH2 in 95% yield further supporting a rapid 1,3-azide shift of 3a and 4a. Mono-substituted allenes RCHCCH2 also undergo carboazidation with aryl iodides and (CH3)3SiN3 in good to excellent yields. For n-butyl-, cyclopentyl- and cyclohexylallene (1b–d), carboazidation gives three isomers 5, 6 and 7 in ca. 1∶1∶1 ratio. For phenyl- and phenoxyallene (1e and f), the reaction produces two stereoisomers Z- (5) and E-CHRC(Ar)CH2N3 (6), where R = Ph and PhO; the regioisomer RCH(N3)C(Ar)CH2 (7) was not observed. In contrast, carboazidation of tert-butylallene (1g) afforded regioisomer t-BuHC(N3)C(Ar)CH2 as the major product (≈90% yield). Based on known palladium-allene and -allyl chemistry, a mechanism is proposed to account for this palladium-catalyzed three-component assembling reaction.

Rhodium-catalyzed chelation-assisted activation of the β-C-H bond of α,β-unsaturated ketoximes and subsequent reaction with alkynes affords highly substituted pyridine derivatives. This new method provides an opportunity for the one-pot synthesis of pyridines with all five positions (C 2 -C 6 ) substituted.

Treatment of phosphites (P(OR)(3)) and MeO(2)CCCCO(2)Me with C(60) affords the corresponding fullerene derivatives (1, R = Me; 2, R = Et; 3, R = n-Bu) consisting of a phosphite ylide group and a cyclopropane ring on the fullerene moiety in high yields. NMR data indicate that all phosphite ylides 1-3 exist as mixtures of E and Z isomers. Under similar reaction conditions, the reaction of phosphinite PPh(2)(OMe) and MeO(2)CCCCO(2)Me with C(60) gives ylide 4. Ylides 1-3 readily undergo hydrolysis with HBr to give corresponding phosphonates 5-7 in excellent yields, while ylide 4 reacts with hydrobromic acid to afford phosphine oxide 8. A mechanism is proposed to account for the formation of these phosphonate derivatives. Further treatment of phosphonate derivative 5 with trimethylsilyl iodide followed by water gave phosphonic acid derivative 9 in 83% yield.

A unique method to introduce phosphorus substituents onto C(60) is based on the reaction of phosphines with acetylenes and C(60). Treatment of C(60) with phosphines (PR(3)) and electron-deficient acetylenes (A) in toluene at ambient temperature gave fullerene derivatives (1, R = C(6)H(5) and A = MeO(2)CCtbd1;CCO(2)Me; 2, R = C(6)D(5) and A = MeO(2)CCtbd1;CCO(2)Me; 3, R = C(6)H(5) and A = EtO(2)CCtbd1;CCO(2)Et; 4, R = p-CH(3)C(6)H(5) and A = MeO(2)CCtbd1;CCO(2)Me; 6, R = C(6)H(5) and A = trans-MeO(2)CCtbd1;CCH=CHCO(2)Me) consisting of a phosphorus ylide group and a cyclopropane ring on the fullerene moiety in good to excellent yields. The structures of these ylide derivatives are determined on the basis of their spectral data and single-crystal X-ray diffraction measurements. All these ylides show temperature-dependent NMR spectra that can be rationalized on the basis of interchange between two Z,E isomers and restricted rotation of the substituents on the fullerene moiety. Based on the known chemistry of phosphines and acetylenes, we propose a mechanism to account for the formation of these ylide derivatives. Phosphine ylides 1 and 4 readily undergo protonation and decarboxylation in the presence of acid to give phosphonium salts 7 and 8, respectively.

Aryl or alkenyl iodides react regioselectively with allenes and hexaalkylditins in the presence of Pd(dba) 2 to give substituted allylstannanes.

Nickel-catalyzed ring-opening reactions of 7-heteroatom norbornadienes and norbornenes with various organic halides to give products with multiple stereocenters are described. Treatment of 7-oxabenzonorbornadiene (1a) and 7-carbomethoxy-7-azabenzonorbornadiene (1b) with aryl iodides (ArI) in the presence of NiCl(2)(PPh(3))(2) and Zn powder gave the corresponding ring-opening addition products cis-1,2-dihydro-2-aryl-1-naphthol (2a-m) and methyl N-[cis-1,2-dihydro-2-aryl-1-naphthyl]carbamate (3a-e) completely stereoselectively in 40-99% yields. The nickel system also catalyzes the reaction of highly substituted oxabicyclic [2.2.1] compounds (1c-e) with organic halides (PhI, PhCH(2)Br, PhCHCHBr, and PhCBrCH(2)) to give the corresponding ring-opening products (4a-d, 5, 6a,b) that consist of four fixed stereocenters. Studies on the effect of solvent on the reaction of 1a with PhI show that CH(3)CN gives the highest yield of product 2a; no product 2a is observed when toluene, dichloromethane, methanol, DMF, or DMSO is used as solvent. Addition of extra PPh(3) to the reaction mixture reduced the yield of 2a. A mechanism is proposed to account for the formation of these nickel-catalyzed ring-opening addition products.

Cyclic enones 2-cyclohexen-1-one (1a), 4,4-dimethyl-2-cyclohexen-1-one (1b), 2-cyclopenten-1-one (1c), and 2-cyclohepten-1-one (1d) react with octa-1,7-diyne (2) in THF in the presence of Ni(PPh(3))(2)I(2), ZnI(2), and Zn powder at 62 degrees C to give [2 + 2 + 2] cycloaddition-dehydrogenation products 3a-d in 32-80% yields. alpha,beta-Unsaturated lactone 5a (5,6-dihydro-2H-pyran-2-one) undergoes [2 + 2 + 2] cycloaddition with 2 to give both the corresponding cyclohexadiene product 6 (29%) and dehydrogenation product 7 (39%). Under similar reaction conditions, 3-buten-2-one reacts with 2 and various substituted hepta-1,6-diynes 9a-c to give [2 + 2 + 2] cycloaddition-dehydrogenation products 11a-d in 68-80% yields. Diphenylacetylene also reacts with 1a-d, 5a, and 2(5H)-furanone (5b) to afford the corresponding [2 + 2 + 2] cocyclotrimerization products 13a-d and 14a-b. No dehydrogenation of products 13 and 14 was observed under the reaction and workup conditions. The reactions of acrylates with alkynes catalyzed by nickel complexes give products that depend greatly on the reaction conditions. Treating ethyl acrylate (15a) with 1-phenyl-1-propyne (16) in the presence of Ni(PPh(3))(2)Cl(2) and Zn at 90 degrees C in toluene affords cocyclotrimerization product 19aas the major product (54% yield). However, treatment of CH(2)CHCOOR (R = Et and t-Bu) with mono alkynes 16 and 12 in the presence of Ni(PPh(3))(2)X(2) (X = Cl and I) and Zn powder in toluene at 60 degrees C affords the corresponding conjugated trienes 17a-c in 82-92% yields. The MS data of 17firmly support an adduct of two molecules of alkyne and a molecule of acrylate. Similarly, the reaction of 15a with octa-1,7-diyne in the presence of Ni(PPh(3))(2)I(2), ZnI(2), and zinc gives triene derivative 21 in 68% yield. NOE and X-ray results indicate that in these trienes the substituents from each alkyne and alkene moiety are cis to each other. The unique stereoselectivity can be attributed to the exclusive formation of seven-membered nickelacycloheptadiene intermediate 25during the catalytic reaction.

A highly homogeneous and nearly monophasic PrBa2Cu4O8 compound has been synthesized at 1 atm of oxygen via a route employing polymeric ethylenediamine/citric acid precursors. The PrBa2Cu4O8 compound with a trace amount of BaCuO2 was synthesized for the first time by sintering the pellets at the temperature of 875 °C under ambient oxygen pressure. The temperature coefficient of the resistivity is positive below 190 K while above 190 K is negative. The superconducting transition was not detected down to 4.2 K. Samples were characterized by X-ray diffraction, scanning electron microscopy, thermal analysis, and transport and magnetic measurements.

An aromatic or olefinic halide RX (C6H5I, p-CH3COC6H4I, p-NO2C6H4I, p-CH3OC6H4I, o-CH3OC6H4I, m-C2H5OCOC6H4I, (Z)-C2H5OCOCHCHI, 3-iodocyclopent-2-en-1-one, 1-iodothiophene, 1-iodonaphthalene, 3-bromo-5,5-dimethylcyclohex-2-en-1-one, or α-bromostyrene), Bu3SnSiMe3 (2), and 1,1-dimethylallene (3a) undergo three-component coupling reaction in toluene in the presence of Pd(dba)2 (dba = dibenzylideneacetone) to give an allylic silane (Me)2CC(R)CH2SiMe3 in good to excellent yields. When X = I, the yields are substantially higher than when X = Br or Cl (no reaction). This carbosilylation reaction is highly regioselective, with the R group adding to the middle carbon and the silyl group to the unsubstituted terminal carbon of 3a. Monosubstituted allenes R‘ ‘CHCCH2 (R‘ ‘ = cyclo-C6H11, n-Bu, and Ph) also undergo carbosilylation with PhI and 2, producing R‘ ‘CHC(Ph)CH2SiMe3 stereoselectively with Z/E between 98/2 and 80/20. Bulkier organic halides and allenes give products with higher Z/E ratios. Based on known pal...

We report the measurements of dynamic light scattering (DLS) and dynamic viscoelasticity on an unsaturated polyester/styrene system at various degrees of curing through sol−gel transition. The meas...

A novel method for the construction of a fused cyclohexadiene ring on C60 based on a nickel-promoted [2+2+2] cycloaddition of 1,6-diynes is described. Treatment of C60 with terminal 1,6-diynes (HC⋮CCH2)2X) in the presence of NiCl2(PPh3)2, Zn, and PPh3 at 90 °C in toluene afforded [2+2+2] bicyclic hexadiene derivatives (X = C(CO2Me)2 (2a), C(CO2Et)2 (2b), C(COMe)2 (2c), CH2 (2d), O (2e), NSO2-p-C6H5CH3 (2f), C(SO2Ph)2 (2g), and (2h) in good yields. Spectral data for products 2a−h indicated that the cycloaddition of diynes to C60 occurs across a 6,6-ring junction on the fullerene. On the basis of the established chemistry of metal-mediated [2+2+2] cycloaddition, a mechanism is proposed to account for the present nickel-mediated reaction. All the hexadiene derivatives 2a−h in solution are readily oxidized by molecular oxygen in the presence of light at ambient temperature. The oxidation process of compound 2a in chloroform-d was monitored by 1H NMR spectroscopy, and the results showed that 2a first reacted w...

Treatment of [60]fullerene with ethyl trans, trans-hexa-2,4-dienoate (1) and methyl trans, trans-octa-2,4-dienoate (2) at 70 ∼ 100 °C afforded products 3 and 4, respectively, which are resulted from Diels-Alder addition of the dienoates to a 6/6 ring junction of [60]fullerene.