Lithium Phenylacetylide Research Articles

Functionalization of Nanocrystalline Porous Silicon Surfaces with Aryllithium Reagents: Formation of Silicon−Carbon Bonds by Cleavage of Silicon−Silicon Bonds

Reaction of nanocrystalline (“porous”) silicon with phenyllithium and lithium phenylacetylide results in functionalization of the silicon surface with phenyl and phenylacetylene moieties, respectively. The reaction proceeds by addition of the aryllithium reagent across a surface Si−Si bond, resulting in a Si−aryl bond and Si−Li species. The highly reactive Si−Li surface species is readily hydrolyzed by water, resulting in significant surface oxidation. The surface-bound Li can also be replaced with H or acyl species by addition of trifluoroacetic acid, acetyl chloride, heptanoyl chloride, or 4-butylbenzoyl chloride. These latter treatments significantly reduce the rate of air oxidation of the porous silicon surface. The nanocrystalline silicon samples used display visible photoluminescence arising from quantum confinement effects. Functionalization with phenyllithium preserves some of the photoluminescence, while the lithium phenylacetylide reaction results in almost complete loss of photoluminescence fro...

Reaction of an alkynyllithium reagent with boron trifluoride: the structure of a likely intermediate in alkynyl anion chemistry

Lithium phenylacetylide reacts with 1 equiv. of BF 3 ·OEt 2 in thf–toluene to yield both a thf adduct of tris(phenylacetylido)borane 2, which is probably the true intermediate in RCCLi/BF 3 -promoted alkynyl anion chemistry, and LiBF 4 , products which are considered to form via sequential LiF elimination from previously proposed acetylidoborate intermediates; complex 2 is the first structurally characterised tris(alkynyl)borane and in the solid state it forms an unusual hydrogen-bonded dimer.

Nucleophilic substitution reactions of ( η6-fluorotoluene)Cr(CO) 3 and ( η6-fluoroanisole)Cr(CO) 3 toward phenylacetylide, fluorenyl, indolinyl and carbazolinyl lithium: crystal structures of tricarbonyl[ η6-(1,2-diphenylethynyl)benzene]chromium and tricarbonyl[ η6-(1,4-fluorenyl)toluene]chromium

Tricarbonyl[ η 6-(1,2-diphenylethynyl)benzene]chromium ( 8a) was obtained along with tricarbonyl[ η 6-(2-phenylethynyl)anisole]chromium ( 7b) and tricarbonyl[ η 6-(3-phenylethynyl)anisole]chromium ( 7a) from the reaction of tricarbonyl( η 6-fluoroanisol)chromium ( 4c) with lithium phenylacetylide ( 3). The formation of ortho- and meta-products, 7b, 8a and 7a, produced in the above reaction demonstrates that the reaction was by no means through a straightforward nucleophilic substitution mechanism. These results provided support for the mechanism proposed by Pauson and Brookhart, in which the nucleophile attacked the carbon atom of the phenyl ring not bearing the leaving group, followed by hydrogen migration and finally elimination of the leaving group to achieve aromaticity. 8a was obtained presumably from the reaction of 7b with excess 3. Compounds were characterized by mass, infrared, 1H, 13C NMR spectra. The molecular structure of 8a has been determined by X-ray diffraction studies. Crystal data are as follows: orthorhombic, P BCA, a = 18.690(2) A ̊ , b = 10.666(2) A ̊ , c = 20.463(2) A ̊ , V = 4079.3(8) A ̊ 3, Z = 8, R =4.41%, R w = 5.56% . Tricarbonyl( η 6-4-fluorenyltoluene)chromium ( 10) was obtained as the only separated product from the reaction of tricarbonyl[ η 6-4-flurotoluene)chromium ( 5) with fluorenyl lithium. The X-ray crystal structure of 10 was determined: monoclinic, P2 1/c, a = 12.318(1) A ̊ , b = 11.498(1) A ̊ , c = 13.585(2) A ̊ , β = 100.35(1)°, V = 1892.8(5) A ̊ 3, Z = 4, R = 3.63%, R w = 5.65% . Tricarbonyl[ η 6-4-fluorenylanisole)chromium ( 11a), tricarbonyl[ η 6-3-fluorenylanisole)chromium ( 11b) and tricarbonyl[ η 6-2-fluorenylanisole)chromium ( 11c) were also produced in moderate to good yields. Moreover, tricarbonyl[ η 6-4-indolinyltoluene)chromium ( 12) and tricarbonyl[ η 6-4-carbazolinyltoluene)chromium ( 14) were synthesized from the reaction of 5 with indolinyl and carbazolinyl lithium, respectively. Tricarbonyl[ η 6-4-indolinylanisole)chromium ( 13a), tricarbonyl[ η 6-3-indolinylanisole)chromium ( 13b) and tricarbonyl[ η 6-2-indolinylanisole)chromium ( 13c) were obtained in high yields from the direct nucleophilic substitution reactions of related compounds.

Structural Variation in Silver Acetylide Complexes: Syntheses and X-ray Structure Determinations of [Ph3PAgC⋮CPh]4·3.5THF and [Me3PAgC⋮CSiMe3]∞

[Ph3PAgC⋮CPh]4·3.5THF (2) can be prepared by the reaction of CpAgPPh3 (1) with lithium phenylacetylide (1:1 equiv). Similarly [Me3PAgC⋮CSiMe3]∞ (4) can be prepared by the reaction of CpAgPMe3 (3) and lithium (trimethylsilyl)acetylide (1:1 equiv). Both complexes have been characterized by elemental analyses, solid-state IR spectroscopy, 1H and 31P NMR spectroscopy, and low-temperature X-ray diffraction studies. The structure of 2 consists of a tetranuclear “flat-butterfly” core, with the two “hinge” silver atoms σ-bonded to two acetylide fragments, which then π-complex the apical Ag(PPh3)2 fragments. In 4, the smaller steric bulk of the phosphine employed allows this complex to crystallize as a polymer. Rather than being constructed from simple [R3PAg(acetylide)] units, both 2 and 4 are formed by the aggregation of (acetylide)2Ag- and Ag(PR3)2+ fragments. The preparation of complexes 2 and 4 demonstrates the synthetic utility of nucleophilic substitution of CpAgPR3 in the synthesis of Ag organometallics. T...

Synthesis and characterization of tricarbonyl[ η6-(phenylethynyl)arene]chromium complexes: crystal structure of tricarbonyl[ η6-(3-phenylethynyl)anisole]chromium

Tricarbonyl( η 6-diphenylacetylene)chromium ( 4) was prepared from the reaction of tricarbonyl( η 6-fluorobenzene)chromium ( 3) with lithium phenylacetylide ( 2) at a low temperature using hexamethylphosphoric triamide as cosolvent. A concomitant tricarbonyl( η 6-butoxylbenzene)chromium ( 6) was also obtained in this reaction probably owing to both the air oxidation of n-BuLi and the ring opening of tetrahydrofuran by n-BuLi. The overwhelming abundance of meta and ortho products 9b and 10b produced in the substitution reaction of tricarbonyl( η 6-fluoroanisole)chromium ( 8a) by lithium phenylacetylide demonstrates that the reaction was by no means through the straightforward S NAr mechanism. The results provide support for the mechanism proposed by Pauson and Brookhart, in which the nucleophile attacked a carbon of the phenyl ring not bearing the leaving group, followed by hydrogen migration and finally elimination of the leaving group to achieve aromaticity. In addition, compounds were characterized by mass, IR, 1H and 13C NMR spectra, and elemental analysis. The molecular structure of tricarbonyl[ η 6-(3-phenylethynyl)anisole]chromium ( 9b) has been determined by X-ray diffraction studies. Crystal data are as follows: P 1; a = 7.782(2) A ̊ and c = 12.688(3) A ̊ ; α = 108.46(3)°, β = 96.05(3)° and γ = 103.19(3)°; V = 797.3(4) A ̊ 3; Z = 2; R = 3.23%; R w = 4.37% .

Open chain 1,3-stereocontrol

Abstract

Preparation, Reactions, and Stereochemistry of 4-tert-Butyl-1-chlorophosphorinane 1-Oxide and Derivatives

Abstract Nucleophilic substitution at tetracoordinated phosphorus centers has been extensively investigated.1 Transesterification of acyclic phosphinates proceeds with inversion of configuration,2 whereas four-membered phosphinates react with retention.3 In previous work4 we suggested that transesterification in six-membered phosphinates occurs via an SN2 mechanism. The title compound was synthesized as a model structure to study the stereochemical and mechanistic aspects of nucleophlic substitution at phosphorus in a six-membered ring. A mixture of diastereomers was produced and separated by column chromatography. Both the mixture and separate isomers were used for an investigation of substitution with methanol, methoxide ions, and phenoxide ions; the reactions proceeded with inversion. Transesterification reactions of the resulting thiophosphinates were studied and found to proceed with inversion. Reactions of these with phenyllithium, benzyllithium, lithium phenylacetylide, and the corresponding organo...

Synthesis and characterisation of enynyl, vinyl and acetylide complexes of osmium(II)

Treatment of [OsH2L4][L = P(OEt)3 or PPh(OEt)2] first with CF3SO3Me and then with an excess of terminal alkynes RCCH (R = But, Ph or p-MeC6H4) produced enynyl derivatives [Os{η3-RC3C(H)R}L4]+1–3. Sequential reactions of [OsH2L4] with CF3SO3Me and activated alkynes R′O2CCCH (R′= Me or Et) or MeO2CCCCO2Me yielded alkenyl [Os{CHC(H)CO2R′}L4]+4, 5 and [Os{C(CO2Me)C(H)CO2-Me}L4]+6 cations, respectively. Spectroscopic data (IR, 1H, 31P, 13C NMR) suggest, in the case of L = P(OEt)3, the presence of two isomers for the alkenyls 4 and 5, with five- and four-membered chelate rings of the vinyl ligand. Hydride–alkynyl [OsH(CCPh)L4] complexes were also obtained by treating [OsH2L4] with CF3SO3Me followed by treatment with lithium phenylacetylide.

X-ray crystal structure of 1,4-diphenylbutadiyne

Crystals of 1,4-Diphenylbutadiyne,1, have been isolated from the decomposition of the cuprate prepared from the reaction between lithium phenylacetylide and copper(I)cyanide in diethylether solution at room temperature. 1,4-Diphenylbutadiyne,I, organizes itself into the expectedherringbone motif in the solid state.

Fluorinated acetylenes. Part 12. Reaction of 3,3,3-trifluoropropynyl-lithium with benzil and α-haloacetophenones

Treatment of 3,3,3-trifluoropropynyl-lithium ( 4) with benzil (2:1 molar ratio) in diethyl ether at −50 °C, followed by addition of an excess of benzoyl chloride, affords 1-benzoyl-5-benzoyloxy-5-phenyl-2,3-bis(trifluoromethyl)cyclopenta-1,3-diene ( 11) (61%) and the 1,4-dialkynyl ester (CF 3CC) 2CPhO 2CPh ( 1b) (8%). Similar reaction of the salt 4 with α-chloroacetophenone (2:1 molar ratio) in diethyl ether at −50 °C, followed by addition of a slight excess of benzoyl chloride, gives the ester CF 3CCPh(CH 2Cl)O 2CPh ( 14a) (55%) and a compound considered to be 2,5-diphenyl-2,5-bis(3,3,3-trifluoropropynyl)-1,4-dioxan ( 15) (30%). Under the same conditions, α-bromoacetophenone yields the corresponding bromo ester CF 3CCCPh(CH 2Br)O 2CPh ( 14b) (39%), 2-phenyl-2-(3,3,3-trifluoropropynyl)oxirane ( 16) (25%) and the dialkynyl ester ( 1b) (7%). The oxirane 16, conveniently prepared (51%) by treatment of salt 4 with the bromoketone (1:1 molar ratio) in THF at −60 °C, on reaction with lithium phenylacetylide followed by addition of benzoyl chloride ( c. 1:1:1 molar ratio) in THF at −60 °C gives a compound identified as 2-phenyl-2-(1-phenyl-5,5,5-trifluoropent-3-en-1-yn-3-yl)oxirane ( 17) or possibly 2-phenyl-2-(3-phenylprop-2-yn-1-yl)-3-(2,2,2-trifluoroethylidene)oxirane ( 18) in 28% yield.

Synthesis and properties of 1-diphenylboryl-2-diphenylphosphino1,2-diphenylethene

Consecutive interaction of lithium phenylacetylide with triphenylborane and diphenylchlorophosphine gave 1-diphenylboryl-2-diphenylphosphino-1,2-diphenylethene, which is less reactive than dialkylborylphosphinoethenes.

Preparation of linear phosphorus compound containing two hypervalent centers. Acetylene-bis[triphenyl(phenylethynyl) phosphorane

A new linear acetylide-connected bis-phosphorane, acetylene-bis[triphenyl)phosphorane] ( 2) was synthesized in the reaction of triphenyl(phenylethynyl)phosphonium bromide with dilithioacetylide. Triphenylbis(phenylethynyl)phosphorane ( 1) was also prepared by a similar treatment of triphenyl(phenylethynyl)-phosphonium bromide with lithium phenylacetylide.

{η6-1,4-(CH3SO3)2C6H4}Cr(CO)3: synthesis, characterization, and reactivity

Reaction of (MeCN)3Cr(CO)3 with hydroquinone in refluxing tetrahydrofuran (THF) produced {η6-1,4-C6H4(OH)2}Cr(CO)3 (1) which was subsequently converted to {η6-1,4-(CH3SO3)2C6H4}Cr(CO)3 (2) by treatment with methanesulfonyl chloride and triethylamine. A single-crystal X-ray study of 2 has been completed and is reported. Treatment of 2 with an oxygen nucleophile gave reaction at sulfur; whereas, treatment of 2 with lithium phenylacetylide resulted in decomposition of the complex to metallic chromium.

ChemInform Abstract: Synthesis and Reductive Elimination of Triarylbis(phenylethynyl)antimony(V).

AbstractThermolysis of the bis(phenylethynyl)triarylantimony derivatives (III), prepared from the triarylantimony dibromides (I) and lithium phenylacetylide (II), yields 1,4‐diphenylbutadiyne (IV) and the arylphenylacetylenes (V), together with the antimony compounds (VI) ‐ (VIII).

Synthesis and reductive elimination of triarylbis(phenylethynyl)antimony (v)

Triarylbis(phenylethynyl)antimony (V) ( 1a - 1c ) were synthesized from triarylantimony dibromide and lithium phenylacetylide. Thermolytic reductive elimination of 1a - 1c took place at 110 °C and the aryl-alkynyl coupling product ( 3 ) increased as the aryl group became more electronegative. The result is consistent with the apical-apical coupling from the trigonal bipyramidal structures, which was predicted to be symmetry-allowed by Hoffmann.

2-(Phenylseleno)prop-2-enenitrile: a three-carbon unit for radical cyclization

Successive reaction of enamines with 2-(phenylseleno)prop-2-enenitrile, lithium phenylacetylide, and triphenyltin hydride serves to generate carbocycles by a process of radical ring closure.

The reaction of lithium phenylacetylide and phenyllithium with N‐(ω‐Bromoalkyl)phthalimides

AbstractLithium phenylacetylide reacted with short‐chain N‐(ω‐bromoalkyl)phthalimides 1b and 1c to give tricyclic products 2b and 2c in moderate yields. Likewise, tricyclic products 3a‐c were obtained when short‐chain imides 1a‐c were treated with phenyllithium. When longer‐chain imides 1d‐f in this series were treated with lithium phenylacetylide only tertiary alcohols 4d‐f could be isolated. Partial hydrogenation of 2b and 2c yielded the corresponding alkenes 5b and 5c, products which corroborated the structural assignment of 2b and 2c.

Dimetallation of phenylacetylene. Selective ortho-substitution

Reaction of lithium phenylacetylide with the complex BuLi–ButOK in a mixture of tetrahydrofuran and hexane leads to the ortho-metallated phenylacetylide; subsequent addition of methyl iodide, dimethyl disulphide, trimethylchlorosilane, and selenium gives the corresponding ortho-substituted phenylacetylenes and benzoselenophen.

ChemInform Abstract: THE REACTION OF 2‐CHLOROAZULENE DERIVATIVES WITH LITHIUM ACETYLIDE IN LIQUID AMMONIA

AbstractReaktion der Chlorazulene (I) bzw. (VI) mit Li‐Acetylid (II) in flüssigem Ammoniak führt zu abnormaler Substitution unter Bildung der Produkte (III), (IV) und/oder (V) bzw. (VII).

The Reaction of 2-Chloroazulene Derivatives with Lithium Acetylide in Liquid Ammonia

Abstract The reaction of diethyl 2-chloroazulene-1,3-dicarboxylate (1a) with lithium acetylide in liq ammonia gave diethyl 4- and 6-ethynylazulene-1,3-dicarboxylates by an abnormal substitution reaction. In a similar manner, some 2-chloroazulenes, possessing alkoxycarbonyl and/or cyano substituents at the 1- and 3-positions of azulene nucleus, gave the corresponding 4 (or 8)- and 6-ethynylazulenes. The same type reaction proceeded when lithium phenylacetylide, sodium indenide, and sodium fluorenide were used as the reagents, 1a giving diethyl 4- and 6-(phenylethynyl)-, 6-(3-indenyl)-, and 6-(9-fluorenyl)azulene-1,3-dicarboxylates, respectively.