Monosubstituted Acetylenes Research Articles

Studies with the Ruthenacarborane Complex [Ru(CO)(PPh3)(THF)(η5-7,8-C2B9H11)]: Reactions with Terminal Alkynes

The syntheses of the complexes [Y][RuX(L)(PPh3)(η5-7,8-C2B9H11)] (X = Cl, Y = K(18-crown-6), L = CO (1), PPh3 (2); X = I, Y = NEt4, L = CO (3)) are reported, and the structure of 3 has been established by an X-ray diffraction study. The anion adopts the “piano stool” structure with the ruthenium atom η5-coordinated on one side by a nido-7,8-C2B9H11 group and on the other by the CO, PPh3, and I ligands. Treatment of 1 with TlPF6 in THF (tetrahydrofuran) affords solutions of the labile species [Ru(THF)(CO)(PPh3)(η5-7,8-C2B9H11)] (5), which readily react with a 3-fold excess of the monosubstituted alkynes RC⋮CH (R = Ph, But, SiMe3). The product from PhC⋮CH is [Ru(CO)(PPh3)(η2: η5-9-(E)-C(H)C(H)Ph-7,8-C2B9H10)] (8), the structure of which was determined by X-ray crystallography. The metal atom is η5-coordinated by the open face of the nido-7,8-C2B9 cage and also η2-coordinated by the CC bond of the E-C(H)C(H)Ph group, the latter being attached to a boron atom in an α-site with respect to the carbons of the ri...

POLYMERIZATION OF 1-BUTYL-2-TRIMETHYLSILYLACETYLENE BY TRANSITION METAL CATALYSTS

New silicon-containing disubstituted polyacetylene was prepared by the polymerization of BTMSA having two bulky substituents (n-butyl and trimethylsilyl) using transition metal catalysts. The polymerization proceeded in a mild manner and the final polymer yield was generally lower than those of silicon-containing monosubstituted acetylenes by the similar catalyst system. The characterization on the polymer structure revealed that the resulting poly(BTMSA) have a conjugated backbone system, but the polymers have peculiar copolymer composition of poly-(BTMSA) and poly(1-hexyne) due to the spontaneous desilylation during the polymerization. The fluoride-ion induced desilylation of poly(BTMSA) using n-Bu4N+F− in THF yielded a completely desilylated product, pure poly(1-hexyne).

Synthesis, structure and antiaggregatory effects of some N-(4,5-dihydro-1 H-imidazol-2-yl)indoles

A series of 1-(4,5-dihydro-1 H-imidazol-2-yl)indole derivatives was prepared in order to evaluate their antiaggregatory activity in human platelets. The compounds 4a– m were prepared by reacting N-aryl- N-(4,5-dihydro-1 H-imidazol-2-yl)hydroxylamines ( 2a– d) with monosubstituted acetylene derivatives 3a– b. Imidazoline derivatives 4 were further acetylated or sulfonylated to give amides 5a– c and sulfonamides 6a– c and 7a– c, respectively. Eight compounds were taken as representative aryliminoimidazoline analogs. Among them only one, 4m, showed a good concentration-dependent action against the primary or α 2-adrenoreceptor mediated phase of noradrenaline-induced aggregation in platelets.

Liquid-Phase Reaction of Monosubstituted and Disubstituted Alkynes with Tetrarhodium Dodecacarbonyl under CO and CO/H2 Mixtures. In-Situ IR Spectroscopic Characterization of 20 New Alkyne−Rhodium Complexes

It is well-known that the liquid-phase homogeneous unmodified rhodium-catalyzed hydroformylation of alkenes is irreversibly poisoned by the presence of trace quantities of alkynes. In the present contribution, we examined the reaction of four series of monosubstituted and disubstituted alkynes (20 compounds) with Rh4(CO)12 in n-hexane solvent at 293 K under both (A) 2.0 MPa CO and (B) 2.0 MPa CO and 2.0 MPa H2. The analytic method used was in-situ high-pressure infrared spectroscopy. It was observed that (I) all alkynes used in this study reacted quantitative with Rh4(CO)12 in a matter of hours, (II) the final spectra were not influenced by the presence of hydrogen, (III) the monosubstituted alkynes consistently gave a final product involving six terminal νCO vibrations in the region 2036−2121 cm-1 and two vibrations at ca. 1668 and 1689 cm-1, and (IV) the disubstituted alkynes consistently gave a final spectrum consistent with the superposition of the spectra obtained in III plus a spectrum involving fiv...

Metathesis polymerization of substituted acetylenes by Mo(NO) 2(O 2CR) 2–Lewis acid catalysts

Mo(NO) 2(O 2CR) 2–Lewis acid catalysts (Lewis acid=TiCl 4, SnCl 4, EtAlCl 2; R=phenyl, methylvaleric, ethylhexanoic) induce monosubstituted acetylenes (phenylacetylene, tert-butylacetylene) to polymerize. The catalytic ability of these catalyst strongly depends on the Lewis acid and solvent. The system with SnCl 4 in benzene is almost selective in polymerization of phenylacetylene (conversion: 60%, yield of polymer 56%) while in toluene cyclotrimers are the main products (conversion: 70%, yield of cyclotrimers: 69%). However, the TiCl 4 system trimerized phenylacetylene in PhCl solution (conversion: 76%, yield of cyclotrimers: 66.5%). The structure of obtained polymers and mechanisms of polymerization and cyclotrimerization reactions were determined.

A versatile synthesis of substituted tetrahydropyridines

A short and efficient synthesis of highly substituted tetrahydropyridines is achieved by a combination of enyne cross metathesis and aza-Diels-Alder reaction under high pressure. The reaction sequence shows atom economy and is compatible with a variety of functionalities being introduced by three building blocks: a monosubstituted alkyne, a terminal alkene, and an imine.

Precise synthesis of monosubstituted polyacetylenes using Rh complex catalysts. Control of solid structure and π-conjugation length

Stereospecific polymerization of monosubstituted acetylenes was successfully performed using a Rh complex, [Rh(norbornadiene)Cl] 2 , as a catalyst, and the resulting polyacetylenes were characterized in detail by 1 H NMR, ESR, laser Raman, diffuse reflective UV, and wide-angle X-ray diffraction. The Rh complex was found to yield selectively the cis-transoid isomer even at room temperature in high yields when alcohol or triethylamine was used as the solvent. Additionally, the resulting cis-polyacetylenes were found to form a pseudohexagonal, columnar self-assembly or superstructure. Further compression of the cis-polymers induced cis-trans isomerization even at room temperature under vacuum, breaking rotationally the cis-C=C bonds and, thus, giving π-radicals as the origin of magnetic properties.

Reactions of the cluster complex [Ru5(μ5-C2)(μ-SMe)2(μ-PPh2)2(CO)11] with terminal alkynes HCCR (R = Ph, But or SiMe3)

Reaction of the dicarbon-containing complex [Ru5(µ5-C2)(µ-SMe)2(µ-PPh2)2(CO)11] 1 with monosubstituted alkynes HCCR (R = Ph, But or SiMe3) yielded [Ru5(µ5-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)10] (R = Ph, But or SiMe3) in which the Ru5 pentagon in 1 is retained. Coupling of the C2 and alkyne moieties forms a CCCHCR ligand which in combination with one Ru atom forms a metallacycle. The unsubstituted terminal carbon has a strong carbidic interaction with four of the Ru atoms. Carbonylation of the R = Ph and SiMe3 complexes yields [Ru5(µ5-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)11] (R = Ph or SiMe3), in which one Ru atom has been extruded from the cluster, although retained by co-ordination to bridging PPh2, SMe and hydrocarbon ligands. A minor product in each case was identified as [Ru5{µ5-CC[C(O)SMe]CHCR}(µ-SMe)(µ-PPh2)2(CO)10 (R = Ph or SiMe3). Here, the organic ligand is formed by combination of the CCCHCR ligand with CO and one of the SMe groups and is attached to an Ru5 core with an open-envelope conformation. Pyrolysis of [Ru5(µ-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)11] afforded [Ru5(µ5-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)10] and [Ru5(µ5-CCCHCR)(µ3-SMe)(µ-SMe)(µ-PPh2)2(CO)9] (R = Ph or SiMe3), in which one SMe group becomes triply bridging. The complex [Ru5{µ5-CC(CHCSiMe3)C(=CHSiMe3)CO}(µ-SMe)2(µ-PPh2)2(CO)8], in which the organic ligand, formed by combination of CO, HC2SiMe3 and CCHSiMe3 molecules, is attached to the opposite side of the open-envelope cluster from that in [Ru5{µ5-CC[C(O)SMe]CHCR}(µ-SMe)(µ-PPh2)2(CO)10], has also been isolated. The structures of five complexes were determined from single-crystal X-ray studies.

Reactions of ( η6-C 6Me 6)RuCl(MDMPP- P, O) and ( η6-C 6Me 6)RuCl(BDMPP- P, O, O) complexes with Lewis bases or alkynes, where MDMPP- P, OP(2-O-6-MeOC 6H 3)Ph 2 and BDMPP- P, O, OP(2-O-6-MeOC 6H 3) 2{2,6-(MeO) 2C 6H 3}

Reaction of [( η 6-C 6Me 6)RuCl(MDMPP- P, O)] 1 (MDMPP- P, OP(2-O-6-MeOC 6H 3)Ph 2] with CO under high pressure at 95° gave RuCl(CO) 3(MDMPP- P, O) 2. [( η 6- p-cymene)Ru(TDMPP- P, O, O)] (TDMPP- P, O, OP(2-O-6-MeOC 6H 3) 2{2,6-(MeO) 2C 6H 3}) reacted with CO or CO/2,6-xylyl isocyanide under high pressure to form Ru(CO) 3(TDMPP- P, O, O) 4 or Ru(CO) 2(XyINC)(TDMPP- P, O, O) 5 (Xyl=2,6-Me 2C 6H 3), respectively. Reactions of 1 with Lewis bases in the presence of NH 4PF 6 gave [( η 6-C 6Me 6)RuL(MDMPP- P, O)](PF 6) 6 (L=CO, XylNC). Complex 1 reacted with mono-substituted acetylenes in acetone in the presence of bases to form the metal alkynyl complexes [( η 6-C 6Me 6)Ru(CCR)(MDMPP- P, O)] 7. Similar reaction of 1 with PhCCH in the presence of NaPF 6 in acetone or MeOH gave a vinylidene 8a (R=CCHPh) and a carbene complex 9a (R=CCH 2Ph(OMe)) [( η 6-C 6Me 6)Ru(R)(MDMPP- P, O)](PF 6), respectively. A reaction of 1 with HCCCMe 2OH and NaPF 6 in MeOH gave a metallabutadiene complex 10c [( η 6-C 6Me 6) Ru{C(OMe)CHCMe 2}(MDMPP- P, O)]. X-ray analyses of 6b (L=XylNC), 7a (R=Ph) and 7e (R=CH 2OH) were carried out to confirm the structures; 6b, monoclinic, space group P2 1/ c (No. 14), a=9.910(8) Å, b=25.370(7) Å, c=16.020(7) Å, β=105.29(5)°, V=3885(7) Å 3, Z=4, R=0.050, R w=0.053 for 4064 reflections ( I>3.0 σ( I)); 7a, orthorhombic, space group Pbca, a=17.222(4) Å, b=23.772(8) Å, c=16.003(8) Å, V=6552(7) Å 3, Z=8, R=0.052, R w=0.052 for 1836 reflections ( I>3.0 σ( I)); 7e, triclinic, space group P 1 (No. 2), a=10.639(4) Å, b=14.778(3) Å, c=10.214(3) Å, α=97.05(2)°, β=113.01(2)°, γ=79.12(2)°, V=1449(2) Å 3, Z=2, R=0.041, R w=0.040 for 3270 reflections ( I>3.0 σ( I)).

Mechanisms of ≡CH bond activation in oxidative carbonylations of alkynes catalyzed by palladium complexes

Three types of catalytic system based on palladium complexes were studied in the synthesis of alkynylcarboxylic acid esters by oxidative carbonylation of monosubstituted alkynes. Three mechanisms were proposed for activation of the ≡CH bond in alkynes and the formation of RC≡C[Pd]X, a key intermediate: (i) electrophilic substitution of H + by Cu(I), (ii) electrophilic substitution of H + by I +, and (iii) oxidative addition of the CH bond in alkynes to palladium.

A Crossed Yne–Ene Metathesis Showing Atom Economy

No special functional groups are required for a new method of selective CC coupling of monosubstituted alkynes such as 1 with alkenes like 2. This crossed yne–ene metathesis also proceeds with atom economy, and provides easy access to such interesting synthetic building blocks as the 1,3-substituted diene 3.

Dehydrogenative Coupling Reactions between a Monosubstituted Alkyne and Monosilane in the Presence of Lithium Aluminum Hydride

A selective dehydrogenative coupling reaction occurs in the presence of LiAlH4 as a catalyst between 1-hexyne and SiH4 to give hexynylsilane and dihexynylsilane. A reaction mechanism involving SiH4 and the alkynylaluminate anion, formed by the interaction between LiAlH4 and the alkyne, is proposed.

Synthesis and Properties of Photoresponsive Polyacetylene Derivatives with an Azobenzene Mesogenic Moiety in the Side Group

We have synthesized novel mono-substituted acetylenes with a photo-responsive azobenzene group and then polymerized them with Ziegler-Natta, metathesis, and Rh based catalysts. Especially, the Rh catalyst containing chloroform as a solvent produced a cis rich polymer with high yield of 90%. Through the measurements of DSC and polarizing microscope, polymer with a n-pentylazobenzene group was found to show a smectic liquid crystalline phase. The reversible photoisomerization of all monomers and polymers was generated due to the irradiation of a UV(350nm) or Visible(450nm) monochromatic light.

Pure WCl 4-catalyst for polymerization of norbornene and monosubstituted acetylenes

A suspension of commercial WCl 4 initiates rapid polymerization of norbornene and norbornadiene under mild conditions. If norbornenyl acetate is used as a substrate, WCl 4 is dissolved and homogeneous polymerization occurs. In both cases polymers ( M ̄ w = about 80 000 ), the structure of which corresponds to the ring-opening metathesis mode of polymerization, were prepared. WCl 4 has also been found to polymerize monosubstituted acetylenes (benzene, 50°C). Poly( t-butylacetylene) of M ̄ w = 600 000 , poly(phenylacetylene) of M ̄ w = 200 000 and poly(1-hexyne) of M ̄ w = 14 000 were prepared in high yields. When WCl 4 was dissolved in the reaction with oxygen-containing compounds (e.g. methyl acetate, acetylacetone, acetophenone) before substrate addition, catalyst activity increased significantly. WCl 4 in 1,4-dioxane was found to be a very active system for phenylacetylene polymerization; it polymerizes this monomer at the monomer-to-catalyst mole ratio equal to 1000 providing polymer of M ̄ w = 400 000 .

Synthesis and properties of Photo-responsive liquid crystalline polyacetylene derivatives

New crystalline conjugated polymer, poly(mono-substituted acetylene) was synthesized by introducing an azobenzene moiety as a mesogen core into side chain. Polymerization of the liquid crystal-substituted acetylene monomer was carried out using a Rh-based or Fe-based catalyst. Polarizing microscope studies demonstrated that the monomer exhibits a“droplets” texture characteristic of a nematic phase, and the polymer a polygonal texture assignable to a smectic phase. Photo-induced reversible cis-trans isomerization of the azobenzene moiety as well as thermal irreversible isomerization from cis to trans form of the polymer backbone were elucidated.

Synthesis and X.p.s. characterization of organometallic Pd containing polymers from monosubstituted acetylenes

Organometallic polymers containing Pd atoms in different co-ordination sites were obtained and characterized. The reactions were performed in a wide range of complex/monomer molar ratios. Functionalized monosubstituted acetylenes, namely propargyl alcohol (POH) and N,N-dimethylpropargylamine (DMPA) undergo coordinative polymerization in the presence of the corresponding bis(triphenylphosphine)bis(acetylide) Pd(II) complexes, [Pd(PPh3)2(CC-CH2OH)2] and [Pd(PPh3)2(CC_CH2N (CH3)2)2]. The complexes are active catalysts for the activation of the CC bond of acetylenic monomers, leading to a π-conjugated C=C backbone. By increasing the complex/monomer ratios, interaction of Pd with the C=C doublel bonds of neighbour chains and with the polymer pendant groups also occurs. © 1997 Elsevier Science Ltd.

Oxidative polycondensation of acetylene by iodine in the presence of a palladium-copper catalyst

A new method for oxidative coupling of mono-substituted acetylenes to corresponding di-substituted butadiynes under anaerobic conditions was applied to polycondensation of acetylene to carbyne, giving both a soluble sticky product and an insoluble black powder. The former was oligoynes that have several lengths of polyyne terminated with phenyl group and the latter resembled carbyne reported before. Electrical conductivity of the latter was an order of 10 −8 S/cm, which increased to an order of 10 −5 S/cm after k doping.

REACTIVITY OF DITHIOPHOSPHORIC ACID TOWARDS SULFURATED MONOSUBSTITUTED ALKYNES IN PRESENCE OF TRANSITION-METAL-CATALYST

Abstract The reactivity of sulfurated monosubstituted alkynes with dithiophosphoric acid (noted Z-H) has been investigated. Depending on the transition-metal-catalyst (Ni, Pd, Rh) and solvent (benzene or THF), two types of alkenes can be isolated: Z-CH[dbnd]CH-CH2-SR and/or Z-C(CH2-SR)[dbnd]CH2. The selectivity of this reaction was studied. 13C and 31P NMR of these new sulfurated alkenes are reported.

Fullerene-acetylene hybrids: Towards a novel class of molecular carbon allotropes

The synthesis and complete characterization of 17 new fullerene-acetylene covalent derivatives is described. Reaction of 3-bromo-1,5-bis(trimethylsilyl)penta-1,4-diyne ( 5) with C 60 gave bis-protected diethynylmethanofullerene 4 in 56% yield. Unsymmetrically bis-protected diethynylmethanofullerene 6 was synthesized in 53% yield from tosylhydrazone 7 and C 60. Proto-desilylation of 4 and 6 gave the corresponding free alkynes 3 and 8 in 83% and 69% yield, respectively. Partial deprotection of 4 afforded mono-protected fullerene 9 in 35% yield. Oxidative hetero-coupling reactions of 3 and 8 under Hay conditions with various monosubstituted acetylenes gave the butadiynylmethanofullerenes 10–13 in yields varying from 25–49%. Homo-coupling of 8 produced dumbbell-shaped fullerene 14, the first dimeric fullerene that could be fully characterized. The X-ray crystal structure analysis of 14 revealed little or no electronic interaction between the two fullerene spheres. Addition of lithium trimethylsilylacetylide to C 60 gave access to 1-substituted-2-(trimethylsilylethynyl)fullerenes. The acidity of hydrofullerene 16, synthesized in 58% yield, was studied as a function of base and solvent. Reaction of lithiated fullerene 17 with various electrophiles is discussed. Alcohol 25 was prepared in 57%yield by reaction of 17 with formaldehyde. Under strongly basic conditions, 25 eliminates formaldehyde to give 16 in quantitative yield. Oxidation of 25 afforded aldehyde 27 in 53% yield, a rather unstable compound that is easily converted to hydrofullerene 16. Conversion of 25 to the corresponding tosylate could be performed in 40% yield.

REACTIVITE DE L'ACID O,O'-DIISOPROPYLDITHIOPHOSPHORIQUE SUR DES ALCYNES VRAIS SULFURES

Abstract Reactivity of O,O'-diisopropyldithiophosphoric acid towards sulfurated monosubstituted alkynes. The reactivity of sulfurated monosubstituted alkynes with O,O'-diisopropyldithiophosphoric acid has been investigated, by three different methods (MeCN, Triton B, AIBN). Two types of alkenes were isolated. The selectivity of this reaction was studied. 13C and 31P NMR of these new sulfurated alkenes were reported.