Naphthalenide Research Articles

Synthetic Studies on Coenzyme Q10

AbstractA practical, highly stereoselective ten‐step synthesis of coenzyme Q10 (1) has been accomplished (overall yield ca. 28%), starting from commercially available 2,3‐dimethoxy‐5‐methylbenzoquinone (Scheme). The introduction of the first side‐chain isoprenyl group with (E)‐configuration (compound 6) was realized by means of a coupling reaction of the aromatic system 3 with oxirane, followed by Swern oxidation and Wittig olefination. The tosyl (Ts) group in the sulfone 9 was selectively removed with sodium naphthalenide in THF to afford 1.

Effect of sodium naphthalenide, a key SET reagent, on trifluoroacetyl derivatives

Aromatic trifluoroacetyl derivatives on treatment with single electron transfer (SET) reagent, sodium naphthalenide, yield symmetrical defluorinated dimers, whereas for aliphatic trifluoroacetyl compounds the reaction usually fails. Investigations have been made for different substituents as well as for similar types of chloro and bromo compounds to establish the scope of the reaction.

Surfactant-Free Synthesis and Functionalization of Gold Nanoparticles

A new, facile and generally applicable synthesis of functionalized gold nanoparticles is presented. It is based on the surfactant-free generation of weakly stabilized nanoparticles by the reduction of HAuCl4 with sodium naphthalenide in diglyme. These nanoparticles were found to lack long-term stability. However, stabilization in both unpolar and polar solvents could straightforwardly be achieved by subsequent addition of various capping ligands. The resulting ligand-capped gold nanoparticles were investigated by TEM microscopy, UV-vis, and FT-IR spectroscopy. Particle core size can be tuned by the amount of reduction agent. The strict separation of the reduction step and the functionalization step in this one-pot synthesis offers an easy and fast access to highly functionalized gold nanoparticles.

A New Agent for Modification of the Teflon Surface

The possibility of preparing modification solutions from sodium naphthalenide wastes and their effect on Teflon adhesion were studied.

Anionic Grafting onto Divinylbenzene-Cross-Linked Polystyrene

Anionic grafting onto divinylbenzene (DVB)-cross-linked polystyrene is described. Using commercially available chloromethylated DVB-cross-linked polystyrene, a lithiated diarylmethyl derivative was prepared by a substitution of the chloromethyl chloride group by phenyllithium, which was followed by an in situ deprotonation by excess phenyllithium. Protonation of this resin led to a neutral phenylmethyl derivative of the original polystyrene that could be deprotonated by n-butyllithium, sec-butyllithium, phenyllithium, or sodium naphthalenide to form an anionic resin that in turn reacts readily with monomers like tert-butyl acrylate or 4-vinylpyridine to form anionically grafted products. Quantitative conversion of the tert-butyl acrylate grafts into poly(acrylic acid) grafts via acidolysis and the application of these poly(acrylic acid) grafts as a precursor for a Pd(0) hydrogenation catalyst is also described.

Reactivity of TEMPO Anion as a Nucleophile and Its Applications for Selective Transformations of Haloalkanes or Acyl Halides to Aldehydes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of the 13-Vertex Rhodacarborane Anion [4-(1,2:5,6-η-cod)-closo-4,1,6-RhC2B10H12]-and Its Reactions with Electrophiles

Reduction of closo-1,2-C2B10H12, with sodium naphthalide in THF (THF = tetrahydrofuran), followed by addition of [Rh2(μ-Cl)2(cod)2] (cod = 1,2:5,6-η-cyclooctadiene) and [N(PPh3)2]Cl, affords the monoanionic 13-vertex rhodacarborane [N(PPh3)2][4-(cod)-closo-4,1,6-RhC2B10H12] (2). Treatment of compound 2 with sources of the cations {Cu(PPh3)}+, {Rh(PPh3)2}+, {Rh(cod)}+, and {RuCl(PPh3)2}+ yields, respectively, the neutral bimetallic species [4-(cod)-3,4,7-{Cu(PPh3)}-3,7-(μ-H)2-closo-4,1,6-RhC2B10H10], [4-(cod)-3,8-{Rh(PPh3)2}-3,8-(μ-H)2-closo-4,1,6-RhC2B10H10], [4-(cod)-3,8-{Rh(cod)}-3,8-(μ-H)2-closo-4,1,6-RhC2B10H10], and [4-(cod)-3,7,8-{RuCl(PPh3)2}-3,7,8-(μ-H)3-closo-4,1,6-RhC2B10H9], of which only the copper derivative has a metal−metal bond. In addition, the reaction of 2 with CF3SO3H results in protonation of the cyclooctadiene ligand with concomitant oxidation of the rhodium center, yielding the ostensibly 16-electron RhIII compound [4-(1−3-η3-C8H13)-closo-4,1,6-RhC2B10H12], which is stabilized by a C−H···Rh agostic interaction. Alternatively, treatment of 2 with hydride-abstracting reagents in the presence of THF results in substitution at a cage BH vertex, forming the zwitterionic complex [4-(cod)-7-{O(CH2)4}-closo-4,1,6-RhC2B10H11].

Effect of Sodium Naphthalenide, a Key SET Reagent, on 3-Substituted Indoles.

For Abstract see ChemInform Abstract in Full Text.

Reactivity of TEMPO anion as a nucleophile and its applications for selective transformations of haloalkanes or acyl halides to aldehydes

Sodium 2,2,6,6-tetramethylpiperidine- N-oxide (TEMPO −Na +), generated by reduction of TEMPO· with sodium naphthalenide in THF, reacted with alkyl halides or acyl halides to produce O-alkylated or acylated TEMPOs, which were in turn oxidized with mCPBA or reduced with DIBAL-H to afford the corresponding aldehydes, thus accomplishing a new protocol for the halides-carbonyls conversion.

Reactivity of a kinetically stabilized 1,3,6-triphosphafulvene toward some nucleophiles

A kinetically stabilized 1,3,6-triphosphafulvene displayed regioselective reactivity toward nucleophiles at the external phosphorus atom (position 6) to afford the corresponding phosphinodiphospholide anions, which gave phosphinodiphospholes after quenching with electrophiles, as well as being readily reduced by sodium naphthalenide suggesting properties similar to fulvenes.

Effect of conformational changes on a one-electron reduction process: evidence of a one-electron P-P bond formation in a bis(phosphinine).

EPR spectra show that one-electron reduction of bis(3-phenyl-6,6-(trimethylsilyl)phosphinine-2-yl)dimethylsilane (1) on an alkali mirror leads to a radical anion that is localized on a single phosphinine ring, whereas the radical anion formed from the same reaction in the presence of cryptand or from an electron transfer with sodium naphthalenide is delocalized on the two phosphinine rings. Density functional theory (DFT) calculations show that in the last species the unpaired electron is mainly confined in a loose P-P bond (3.479 A), which results from the overlap of two phosphorus p orbitals. In contrast, as attested by X-ray spectroscopy, the P-P distance in neutral 1 is large (5.8 A). As shown by crystal structure analysis, addition of a second electron leads to the formation of a classical P-P single bond (P-P 2.389 A). Spectral modifications induced by the presence of cryptand or by a change in the reaction temperature are consistent with the formation of a tight ion pair that stabilizes the radical structure localized on a single phosphinine ring. It is suggested that the structure of this pair hinders internal rotation around the C-Si bonds and prevents 1 from adopting a conformation that shortens the intramolecular P-P distance. The ability of the phosphinine radical anion to reversibly form weak P-P bonds with neutral phosphinines in the absence of steric hindrance is confirmed by EPR spectra obtained for 2,6-bis(trimethylsilyl)-3-phenylphosphinine (2). Moreover, as shown by NMR spectroscopy, in this system, which contains only one phosphinine ring, further reduction leads to an intermolecular reaction with the formation of a classical P-P bond.

Platinum Complexes of Naphthalene‐1,8‐dichalcogen and Related Polyaromatic Hydrocarbon Ligands

Platinum bisphosphine complexes bearing dichalcogen-derivatised naphthalene, acenaphthene or phenanthrene ligands have been prepared by either oxidative addition to zero-valent platinum species or from [PtCl(2)(PPhR(2))] (R=Ph or Me) and the disodium or dilithium salts of the parent disulfur, diselenide or mixed S/Se species. The parent naphthalene, acenaphthene and phenanthrene chalcogen compounds were treated with either [Pt(PPh(3))(4)] or [Pt(C(2)H(4))(PMe(3))(2)] (prepared in situ from [PtCl(2)(PMe(3))(2)], ethene and sodium naphthalide or super hydride [LiBEt(3)H]) to give the appropriate platinum(II) species. The dilithium salts of 1,8-E(2)-naphthalene (E=S or Se) prepared in situ by reduction of the E-E bond with [LiBEt(3)H] were treated with [PtCl(2)(PPh(3))(2)] to give [Pt(1,8-E(2)-nap)(PPh(3))(2)]. The tetraoxides [Pt(1,8-(S(O)(2))(2)-nap)(PR(3))(2)] (PR(3)=PPh(3) or PMe(2)Ph) were prepared in a similar metathetical manner from the appropriate [PtCl(2)(PR(3))] complexes and the disodium salt of naphthalene 1,8-disulfinic acid (1,8-(S(O)ONa)(2)-nap). The X-ray structures of selected examples reveal bidentate coordination with the naphthalene-E(2) unit hinged (111-137 degrees) with respect to the coordination plane. The naphthalene ring suffers significant distortion from planarity.

Reductive activation of carbon-fluorine bonds in perfluoroalkyl ligands: an unexpected route to the only known tetrafluorobutatriene transition metal complex: Ir(eta 5-C5Me5)(PMe3)(2,3-eta 2 -CF2[double bond]C[double bond]C[double bond]CF2).

Six-electron reduction of the perfluoro-sec-butyl ligand in Cp*Ir(PMe3)I(C4F9) with sodium naphthalenide affords the first known example of a transition metal complex of tetrafluorobutatriene, Cp*Ir(PMe3)(C4F4). The free ligand is a highly unstable compound. The compound has been completely characterized by a single-crystal X-ray diffraction study; the center coordinated double bond shows significant elongation, and the flanking fluoroalkenes show significant shortening, as compared to the dimensions in the free ligand.

Generation of highly stable amidate anion in anionic polymerization of 3-(triethylsilyl)propyl isocyanate

To study living anionic polymerization, 3-(triethylsilyl)propyl isocyanate (TEtSPI) monomer was synthesized by hydrosilylation of allylamine with triethylsilane and treatment of the resulting amine with triphosgene. The polymerization of TEtSPI was performed with sodium naphthalenide (Na-Naph) as an initiator and in the absence and presence of sodium tetraphenylborate (NaBPh4) as an additive in tetrahydrofuran (THF) at −78 and at −98 °C. A highly stabilized amidate anion for living polymerization of isocyanates was generated for the first time with the combined effect of the bulky substituent and the shielding action of the additive NaBPh4, extending the living character at least up to 120 min at −98 °C. Even the anion could exist at −78 °C for 10 min. A block copolymer, poly(n-hexyl isocyanate)-b-poly[(3-triethylsilyl)propyl isocyanate]-b-poly(n-hexyl isocyanate), was synthesized with quantitative yields and controlled molecular weights via living anionic polymerization in THF at −78 °C for TEtSPI and −98 °C for n-hexyl isocyanate, respectively, with Na-Naph with three times of NaBPh4 as a common ion salt. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 933–940, 2004

Effect of Sodium Naphthalenide, a Key Set Reagent, on 3-Substituted Indoles

Action of the single electron transfer (SET) reagent sodium naphthalenide on 3-substituted indoles revealed that indoles with electron-donating substituents do not respond whereas indoles with electron-withdrawing substituents easily react, yielding several products depending upon the substituent.

Reductive Decomplexation of π‐Allyltricarbonyliron Lactone Complexes Using Sodium Naphthalenide as a Route to Stereodefined 1,7‐Diols and 2,3‐Diene‐1,7‐diols.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of an enantiopure 2-arylcyclohexanols from prochiral enol acetates by an enantioselective protonation/diastereoselective reduction sequence

The enantioselective protonation with 2-sulfinyl alcohols of lithium enolates of 2-arylcyclohexanones with different substituents on the phenyl group takes place with excellent enantioselectivities (89–99%). Chiral 2-phenylcyclohexanone and 2-arylcyclohexanones carrying electron donor substituents on the aromatic ring are converted into the corresponding trans-2-arylcyclohexanols by diastereoselective reduction with sodium naphthalenide in the presence of acetamide. The stereochemical integrity of the tertiary stereocenter is fully preserved using this reduction procedure. Interestingly, the chiral proton source is not consumed in the synthesis.

Bis(μ-di-tert-butylphosphido)bis[(triethylphosphine)palladium(I)](Pd—Pd)

The title compound, [Pd2(C8H18P)2(C6H15P)2], has been obtained by the reaction of di-tert-butyl­phosphine–phos­phanyl­idene–σ4-di-tert-butyl­(methyl)­phospho­rane and bis­(tri­ethyl­phosphine)­palladium(II) chloride with sodium naphthalide. [{Pd(μ-PtBu2)(PEt3)}2](Pd—Pd) is not a primary product. It crystallizes in space group P\overline 1 with one mol­ecule in the unit cell. The molecule has a centre of symmetry at the mid-point of the Pd—Pd bond.

Reductive decomplexation of pi-allyltricarbonyliron lactone complexes using sodium naphthalenide as a route to stereodefined 1,7-diols and 2,3-diene-1,7-diols.

Treatment of pi-allyltricarbonyliron lactone complexes, that contain an adjacent leaving group, with lithium naphthalenide causes decomplexation to acyclic dienols in excellent yield and without any stereochemical scrambling of the allylic centre. When an endo complex is employed (E,E)-geometry prevails with good selectivity whereas (Z,E)-geometry dominates in the case of exo complexes. A mechanism consistent with the observed stereo- and regiochemistry is proposed.

Dianionic platinadiphospholene complexes.

1,2,3,4-tetraphenyl-1,2-dihydrodiphosphetene 1 reacts with lithium or sodium naphthalenide to afford the corresponding dianionic salts 2 and 3. An X-ray crystal structure analysis shows that dianion 3 of general formula [(1)2-2Na3(DME)2, Na(DME)3] is a polymeric structure consisting of [(1)2-2Na3(DME)2] units which are connected together through one sodium atom. Reaction of the dianionic lithium salt 2 with [Pt(COD)Cl2] affords the 4[Li(2.2.1)]2 complex, after the addition of 2 equiv of (2.2.1) cryptate. The overall geometry around platinum in 4[Li(2.2.1)]2 can be described as distorted square planar, and only the diastereomer (1-R, 2-S, 3-R, 4-S) is formed. X-ray data indicate that no delocalization takes place within each platinadiphospholene unit and that complex 4[Li(2.2.1)]2 must be regarded as the coordination of two molecules of dianion 2 onto a Pt2+ center. Reaction of the dianionic sodium salt 3 with 1 equiv of [Pt(COD)Cl2] produces the 4[Na(DME,Et2O)]2 complex which adopts a pseudotetrahedral geometry around platinum ( between interplane angles = 35), the two cationic units [Na(DME, Et2O)] being located along a C2 axis. Four weak interactions exist between the sodium cations and the phosphorus atoms. Only the (1-S, 2-S, 3-S, 4-S) diastereomer is formed. Bond distances in the diphospholene units of 4[Na(DME,Et2O)]2 are close to that of dianion 3 indicating that, like in 4[Li(2.2.1)]2, the complex can be described as a platinum (+2) dianionic species.