Polymerization of Substituted Acetylenes Carrying Non‐Polar and Polar Groups with Transition Metal Acetylide Catalysts

A new series of single‐component air‐stable transition metal acetylide catalysts for the polymerization of substituted acetylenes carrying non‐polar and polar groups was developed. The catalytic properties of transition metal acetylides are related to transition metals, phosphines and acetylenic ligands. Nickel acetylides show higher catalytic activity towards the polymerization of substituted acetylenes containing non‐polar groups, while palladium acetylides show higher catalytic activity towards the polymerization of substituted acetylenes carrying polar groups. Palladium acetylides with PPh₃ ligand are efficient catalysts for the polymerization of substituted acetylenes bearing both non‐polar and polar groups.     

Chemical ionization mass spectra of mononitroarenes

The H₂ and CH₄ chemical ionization mass spectra of a selection of substituted nitrobenzenes have been determined. It is shown that reduction of the nitro group to the amine is favoured by high source temperatures and the presence of water in the ion source. The H₂ chemical ionization mass spectra are much more useful for distinguishing between isomeric compounds than the CH₄ CI mass spectra because of the more extensive fragmentation. For ortho substituents bearing a labile hydrogen abundant [MH ? H₂O]⁺ fragments are observed. When the substituent is electron-releasing both ortho and para substituted nitrobenzenes show abundant [MH? OH]⁺ fragment ions while meta substituted compounds show abundant loss of NO and NO₂ from [MH]⁺. The latter fragmentation is interpreted in terms of protonation para to the substituent or ortho to the vitro function, while the first two fragmentation routes arise from protonation at the nitro group. When the substituent is electron-attracting the chemical ionization mass spectra of isomers are very similar except for the H₂O loss reaction for ortho compounds.     

Efficient halogenation of unsaturated organoaluminum compounds with sulfonyl halides

Alkenylalumanes prepared by carbo-or cycloalumination of substituted acetylenes reacted with an equivalent amount of sulfonyl halide (MsCl, TsCl, PhSO₂Cl, MsBr) in methylene chloride or hexane at room temperature to produce alkenyl halides in high yields. Electron-donor solvents such as diethyl ether or tetrahydrofuran inhibited the halogenation process. β-Substituted vinylalumanes generated by hydroalumination of substituted acetylenes failed to react with sulfonyl halides.     

One‐Shot Double Elimination Process: A Practical and Concise Protocol for Diaryl Acetylenes

A variety of diaryl acetylenes were obtained in good yields when lithium hexamethyldisilazide was added to a solution of arylmethyl sulfone, aryl aldehyde, and chlorodiethylphosphate in THF. In this one‐shot process, a number of transformations such as aldol reaction, phosphorylation of aldolate, and double elimination of the resulting β‐substituted sulfone proceeded successively to afford the desired acetylenes. The one‐shot process was accelerated by the substitution of halogen atoms on the phenyl groups, and unsymmetrically substituted diaryl acetylenes were obtained without contamination of the dehalogenated products. Diaryl acetylenes with other substituents such as CF₃, ethoxycarbonyl, dimethylamino, TMS‐acetylene groups, as well as pyridinyl and thienyl moieties were also accessible with this method. However, methoxy‐substituted compounds were obtained in moderate yields under the same conditions, but the yields were increased when lithium diisopropylamide was used instead.     

Studies with condensed amino‐thiophenes: Further investigation of reactivity of amino‐thieno‐coumarines and amino‐thieno‐benzo[h]coumarines toward electron‐poor olefins and acetylenes

The reaction of 3‐amino‐5‐oxa‐2‐thia‐cyclopenta[a]naphthalene‐4‐one 2b with substituted acetylenes afforded C‐1 alkylation products. On the other hand, reaction of 17‐amino‐15‐methyl‐11‐oxa‐16‐thiacyclopenta[a]phenanthrene‐12‐one 5 with substituted acetylenes and electron‐poor olefins afforded the condensed thienopyridine derivatives 7 and 11a – c . The reaction of 5 with acrylonitrile and with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione afforded compounds 13 and 21 with loss of H₂S via the expected [4 + 2] cycloaddition sequence. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:502–507, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20047     

A convenient and efficient ring-opening reaction of aziridines with acetylenes and synthesis of dihydropyrroles

In the presence of ^tBuOK, reaction of acetylenes with N-Ts substituted aziridines derived from both cyclic and acyclic alkenes at room temperature gave rise to homopropargylamines in good to high yields and in high regioselectivity. Not only Ph- and Me₃Si-substituted acetylenes but also acetylene itself was suitable reagents. Treatment of ring-opening products with I₂ and AgOAc in the presence of K₂CO₃ provided dihydropyrroles in high yields. One-pot synthesis of dihydropyrroles was also realized by the reaction of aziridines and phenylacetylene in the presence of NaH followed by the treatment with I₂ and AgOAc.     

First synthesis of magnesacyclopentadienes from acetylenes by treatment with BuMgHlg in the presence of Zr complexes

Treatment of internal acetylenes and allenes with BuMgHlg (Hlg = Cl, Br) in the presence of Cp₂ZrCl₂ selectively leads to the formation of substituted magnesacyclopenta-2,4-dienes and alkylidenemagnesacyclopentenes.     

Synthesis and Reactions of Phosphorus Substituted Acetylenes

Abstract

To construct phosphorus-functional group substituted Ir-electron systems, synthesis of acetylenes possessing phosphorus substituents and the reactions with CpCo(CO)₂ were investigated.     

Substituted 6-ethynyl-1.4-naphthoquinones

Conclusions Syntheses are reported for substituted 6-ethynyl-1,4-naphthoquinone by the condensation of 6-iodo-1,4-dimethoxynaphthalene or 6-iodo-1-naphthol with terminal acetylenes and subsequent oxidation using Ce(NH₅)₂(NO₃)₆ and ON(SO₃K)₂.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 485–488, February, 1988.     

Reactions of C5H5M (M = Fe, Ni) with substituted thiophenes

The ion molecule reactions between C₅H₅M⁺ (M = Fe, Ni) with some substituted thiophenes have been studied in an ion trap mass spectrometer. The reactions of halogen substituted thiophenes lead to the formation of a new C-C bond between the cyclopentadiene ring and the thiophene with the loss of a neutral HX. The reaction mechanism has been investigated by means of DFT calculations and it was found that the insertion of the metal atom in the C-X bond is the key step in the process.     

Rhodium-catalyzed highly selective thioformylation of acetylenes with thiols and carbon monoxide

Highly regioselective thioformylation of terminal acetylenes with thiols and carbon monoxide has been developed by the use of rhodium(I) complexes as the catalyst: formyl and thio groups are introduced into the terminal and inner positions of acetylenes, respectively. The thioformylation is performed in the presence of a catalytic amount of rhodium(I) complexes, such as RhH(CO)(PPh₃)₃, RhCl(PPh₃)₃, and RhCl(CO)(PPh₃)₂, under the pressure of CO (3 MPa) at 120°C in CH₃CN to provide β-thio-α,β-unsaturated aldehydes in good yields. This thioformylation can be applied to a variety of terminal acetylenes and aromatic thiols. A mechanistic proposal includes the formation of the rhodium sulfide complex as the key species.     

Mass spectra of heterocyclic compounds. II-Hexahydro-1,3,5,-triazines

The twelve tri-N-sulphonylhexahydro-1,3,5-triazines (R = alkyl or aryl) exhibit a common fragmentation pattern; most of the fragments are directly or indirectly generated from the [M ? RSO₂]⁺ ion. Tri-N-Benzylsulphonylhexahydro-1,3,5-triazine (R = PhCH₂) departs from the others mainly because the key ion [M ? RSO₂]⁺ suffers a skeletal rearrangement with loss of SO₂. The rationalizations presented are supported by metastable evidence, accurate mass measurements and deuterium labelling.     

Some heterocyclic derivatives of sterically hindered phenols

Five- and six-membered heterocyclic compounds containing sterically hindered phenols as structural fragments were obtained by dipolar 1,3-eycloaddition of substituted nitrile oxides to olefins, azomethines, and acetylenes.Translated fromIzvestiva Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 426–429, February, 1996.     

Synthesis of cyclopropane-containing organoaluminum compounds by the reaction of acetylenes with CH<Subscript>2</Subscript>I<Subscript>2</Subscript> and Et<Subscript>3</Subscript>Al

Reactions of disubstituted and terminal acetylenes with CH₂I₂ and Et₃Al in the molar ratio 1: 4: 6 lead to the selective formation of organoaluminum compounds containing di-, tri-, or tetrasubstituted cyclopropane fragments depending on the nature of acetylene and reaction conditions.     

SYNTHESE POLYCYCLISCHER [C]-ANELLIERTER THIOPHENE

Abstract

A benzene ring substituted with two acyl groups in ortho-position was built from α-dicarbonyl compounds and dibenzyl ketone via Diels-Alder reaction of the intermediate cyclopentadienones with 1,2-diaroyl acetylenes and subsequent decarbonylation. The polycycles which were synthesized in this way formed interesting new [c]-annellated thiophenes on reaction with tetraphosphorus decasulfide (P₄S₁₀).     

A regioselective synthesis of 3-benzazepinones via intramolecular hydroamidation of acetylenes

Synthesis of 3-benzazepinones by palladium-catalyzed intramolecular addition of amides to alkynes is achieved. Phenyl acetylenes substituted in the ortho-position with tethered amide functionality were prepared in a few steps from readily available starting materials. It was found that 5% Pd(OAc)₂(PPh₃)₂ and KOH most effectively promoted cyclization. When the tethered group is an acetamide and an alkyl substituent is on the acetylene unit, regioselective 3-benzazepinone synthesis could be achieved in good yields.     

Ortho,Effects in organic molecules on electron impact: X—unusual ortho effects of the methyl group in o-picolinotoluidide

The mass spectrum of o-picolinotoluidide gives rise to three major fragments at m/z 184, m/z 169 and m/z 168, corresponding to the loss of CO from the molecular ion followed by the loss of ?H₂ and ?H₃ by independent pathways. It has been shown that the ortho methyl group and the nitrogen of the pyridine ring in the 2-position are involved in the formation of these three major fragments observed in the mass spectrum of o-picolinotoluidide. The mass spectrum of 2-(o-toluidino) pyridine, the molecular ion of which can resemble the [M? CO]⁺ ion in o-picolinotoluidide, also shows loss of CH₃ and NH₂ radicals from the molecular ions. Based on these observations coupled with the high resolution data, the mass analysed ion kinetic energy spectrometry and high voltage scans of these fragments in both the compounds, two mechanistic pathways have been proposed for the formation of these ions in o-picolinotoluidide.     

One-pot synthesis of 2,3,5-substituted 1H-pyrroles via the reaction of terminal acetylenes with nitriles and EtAlCl2 catalyzed by Сp2TiCl2

A new one pot method for the synthesis of 2,3,5-substituted 1H-pyrroles in moderate to good yields (58–77%) based on multicomponent reaction of terminal acetylenes with nitriles and EtAlCl₂ in the presence of Сp₂TiCl₂ catalyst and metallic magnesium has been developed. The possible mechanistic pathway to substituted pyrroles is discussed.     

Chain transfer reaction in the polymerization of substituted acetylenes. II. Chain transfer reaction to trimethylvinylsilane in the polymerization of disubstituted acetylenes by MoCl5–n-Bu4Sn

The effect of various olefins as chain transfer agents was studied in the polymerization of 1-chloro-1-octyne, 1-chloro-2-phenylacetylene, 2-octyne, etc., catalyzed by MoCl₅–n-Bu₄Sn (1 : 1). Si-containing olefins, especially trimethylvinylsilane, greatly lowered the polymer molecular weight in the polymerization of the Cl-containing acetylenes, e.g., the M _n of poly(1-chloro-1-octyne) was 4.2 × 10⁵ without an olefin, whereas it decreased to 3.4 × 10⁴, i.e., below 1/10 in the presence of trimethylvinylsilane (1/2 equiv to monomer). In contrast, the molecular weight of poly(2-octyne) did not decrease that much, even with trimethylvinylsilane. The Cl-containing polyacetylenes obtained in the presence of trimethylvinylsilane as chain transfer agent possessed the trimethylsilyl group. Thus, the present study enables control of the molecular weight of substituted polyacetylenes by chain transfer, and further verifies the metal carbene mechanism for the polymerization of substituted acetylenes. © 1993 John Wiley & Sons, Inc.     

Zur lokalisierung funktioneller gruppen in steroiden mit hilfe der massenspektrometrie—VII : 3,11-Dihydroxypregnan-20-one

The mass spectrometric degradation reactions of 3,11-dihydroxypregnan-20-ones concern mainly cleavage reactions in the D ring. Characteristic fragments are the ions of mass 43 combined with ions of mass 84 and 85. Equally, after single and double loss of water CH₃CO? is eliminated, as well as C 15–17, C20 and C21.All spectra of 3,11-dihydroxypregnan-20-ones are characterised by a key fragment of mass 190 produced by cleavage of bonds in the B ring.Ions with an 11α-OH group show important ions of mass 124 which are dominating if the A/B ring system is cis connected. In contrast the configuration of an OH group in position 3 can hardly be deduced by the spectra.