Sodium naphthalenide reduction

The remarkable hexanuclear complex [ NiCp ] (81), prepared by the sodium naphthalenide reduction of nickelocene, undergoes an extensive series of reversible one-electron transfer reactions cyclic voltammetry shows waves relating the six species [ NiCp 6] (Z = -2 to 3). Chemical oxidation of 81, with Ag, gave the monocation whose structure shows only a small tetragonal distortion from the octahedral array of nickel atoms in the neutral precursor (198). 

SCHEME 14. Proposed mechanism for the sodium naphthalenide reduction with retention of configuration... 

Pattenden and Robertson [76] reported a very interesting cathodic reduction of a variety of terminal allenic ketones that were cyclized highly stereoselectivity through the exo mode, producing five-membered rings. It is particularly notable that the products formed in the electrochemical and chemical (sodium naphthalenide) reductions are structural isomers, but with the same configuration ... 

Generation of the electron-rich, coordinatively unsaturated species, Ru(dmpe)2, by sodium naphthalenide reduction of Ru(dmpe)2Cl2 leads to insertion into a C—H bond... 

Sulfonamides (R2NSO2R ) are prepared from an amine and sulfonyl chloride in the presence of pyridine or aqueous base. The sulfonamide is one of the most stable nitrogen protective groups. Arylsulfonamides are stable to alkaline hydrolysis, and to catalytic reduction they are cleaved by Na/NH3, Na/butanol, sodium naphthalenide, or sodium anthracenide, and by refluxing in acid (48% HBr/cat. phenol). Sulfonamides of less basic amines such as pyrroles and indoles are much easier to cleave than are those of the more basic alkyl amines. In fact, sulfonamides of the less basic amines (pyrroles, indoles, and imidazoles) can be cleaved by basic hydrolysis, which is almost impossible for the alkyl amines. Because of the inherent differences between the aromatic — NH group and simple aliphatic amines, the protection of these compounds (pyrroles, indoles, and imidazoles) will be described in a separate section. One appealing proj>erty of sulfonamides is that the derivatives are more crystalline than amides or carbamates. 

A number of nitrogen-fixing bacteria contain vanadium and it has been shown that in one of these, Azotobacter, there are three distinct nitrogenase systems based in turn on Mo, V and Fe, each of which has an underlying functional and structural similarity.This discovery has prompted a search for models and the brown compound [Na(thf)]+[V(N2)2(dppe)2] (dppe = Pli2PCH2CH2PPh2) has recently been prepared by reduction of VCI3 by sodium naphthalenide... 

Alkene formation can also be achieved using potassium/graphite (C8K) or sodium naphthalenide for reduction.172 The reductant prepared in this way is more efficient at... 

The dropwise addition of sodium naphthalenide to THF containing vanadium trichloride and l,2-bis(dimethylphosphino)ethane (dmpe) causes changes of colours suggesting a stepwise reduction from +2 to 0. Brown [V(dmpe)3] was isolated41 (fieff = 2.10BM) and IR data suggest octahedral coordination. The same complex was synthesized by a metal vapour technique.42 The ESR was that expected and the unit cell is cubic with a = 11.041(3) A. 

The monomeric carbonyl complexes of d M1 isolated so far are mainly the seven-coordinated [MX(CO)2(dmpe)2] compounds (M = Nb, X = Cl, Br, N3 697 M = Ta, X = H, Cl, Br, CN, Me, Et, Pr ) (53) has been obtained by reduction of [TaCl2(dmpe)2] with one equivalent of sodium naphthalenide under CO the other tantalum derivatives were generally prepared by oxidative additions to [Ta(CO)2(dmpe)2] formed in situ by reduction of (53 Scheme 10). The niobium analogs were formed by reductive carbonylation of [NbCU(dmpe)2].698... 

Reduction reactions of nickel(If) compounds. The reduction of nickel(II) compounds to yield nickel(0) phosphine complexes has been carried out using a variety of reducing agents such as sodium amalgam, sodium sand, sodium borohydride, sodium naphthalenide and aluminum trialkyls. In some cases the phosphine ligand itself was found to act as the reducing agent. 

Primary ally lie amines1 In the presence of this catalyst, allylic chlorides or acetates react with sodium p-toluenesulfonamide in THF/DMSO (80 20) to form the corresponding allylic sulfonamide in 60-85% yield. The products are converted into primary allylic amines on reductive cleavage (sodium naphthalenide). 

Of the homoleptic carbonylmetallates(l -) we have attempted to reduce, [Co(CO)4] appears to be the most difficult. Although the sodium salts of [M(CO)6] (M = V, Nb, and Ta) were quickly reduced in liquid ammonia by sodium metal to provide the corresponding trianions, [M(CO)5]3 (vide supra), it seems unlikely that we have ever effected complete reduction of Na[Co(CO)4] to Na3[Co(CO)3]. Even after 2 days of refluxing (at — 33°C) anhydrous ammonia solutions of Na[Co(CO)4] with excess Na, considerable amounts of the tetracarbonylcobaltate(l —) remained. Low yields of a heterogeneous-appearing brown to olive-brown insoluble solid were isolated this solid has been shown to contain Na3[Co(CO)3] (vide infra). As in the case of [Re(CO)s], we found that solutions of potassium in liquid ammonia were far more effective at reducing [Co(CO)4]-. However, unlike [Re(CO)s], [Rh(CO)4], or [Ir(CO)4] (vide infra), there was no evidence that [Co(CO)4] was reduced by sodium or potassium metal in hexa-methylphosphoric triamide. We observed that excess sodium naphthalenide slowly (over a period of 40-50 hr at room temperature) converted Na[Co(CO)4] in THF to an impure and insoluble brown powder that contained Na3[Co(CO)3], but this synthesis appeared to be of little or no utility. 

From a synthetic objective it is unfortunate that attempts to produce the dianion of OFCOT by various reduction procedures have not resulted in a stable dianion. Although the organic decomposition products resulting from reduction by alkali metals or sodium naphthalenide are unknown, fluoride ion is produced (126). However, the nine-7t-electron radical anion has been produced at low temperatures by y irradiation of OFCOT, and electron spin resonance (ESR) spectroscopy indicates that it possesses the anticipated planar delocalized D8b structure 55 (127). The unavailability of the dianion... 

Reductive cyclization of y-ethynyl ketones to allylic alcohols. This reaction was first reported by Stork et al., who used an alkali metal and liquid ammonia.1 The main by-products, at least in cyclization to A-norsteroids, result from overreduction. This side reaction can be prevented by use of sodium naphthalenide in THF or DME.2... 

Reductive cleavage of sulfonamides.2 Sodium naphthalenide can be used for this reaction, but it does not cleave mesyl amides of primary and dialkyl amines. A wide variety of sulfonamides is cleaved with potassium and dicyclohexyl-18-crown-6. 

The submitters report that the sodium naphthalenide color Is discharged upon addition of the hydroxylamine mixture, and that completion of the reduction 1s Indicated by reappearance of the characteristic blue-green color of the reagent. The checkers did not observe disappearance of the reagent color. 

In addition to the procedure given here for the oxidation of tert-octylamine to nitroso-tert-octane,2 the oxidation may be carried out with m-chloroperoxybenzoic acid or with a solution of peroxyacetic acid in ethyl acetate.4 The lead dioxide oxidation of alkyl hydrazines to alkyl radicals appears to have general application. In addition to tert-butylhydrazine, various secondary alkylhydrazines (e.g., bornylhydrazine and menthylhydrazine) have been used to good effect. The reduction of tri-tert-alkylhydroxyl amine to the di-tert-alkylamine has also been achieved with sodium in ammonia but the insolubility of the hydrophobic substrate makes this procedure difficult. The use of sodium naphthalenide gives higher yields and is more reproducible. 

Reduction of RuMe2(OEP) with sodium naphthalenide, NaNp, led to decomposition of the anion thus formed (sequence 25) [308]. 

Reduction of [Mo(CO)2(bpy)2] using sodium amalgam or sodium naphthalenide gives paramagnetic [Mo(CO)2(bpy)2] in dimethoxyethane (81JOM(218)C31). Oxidation of [Mo(CO)2(bpy)2] using silver tetrafluoroborate in acetonitrile or aluminum chloride in methylene chloride and followed by sodium tetrafluoroborate gives... 

In 1973, the direct potassium metal reduction of zinc salts was reported.3 This active zinc powder reacted with alkyl and aryl bromides to form the alkyl- and arylzinc bromides under mild conditions.4 The reduction of anhydrous zinc salts by alkali metals can be facilitated through the use of electron carriers. Lithium and sodium naphthalenide reduce zinc salts to give highly reactive metal powders under milder and safer conditions. Graphite5 and liquid ammonia6 have also been employed as electron carriers in producing zinc powders. A highly dispersed reactive zinc powder was formed from the sodium metal reduction of zinc salts on titanium dioxide.7... 

The insertion of a tin atom into a nonicosahedral carborane framework was first reported by Grimes and co-workers (233), following approaches similar to those which had previously been successful with transition metal reagents. Reduction of c/oso-2,4-C2B5H7 with sodium naphthalenide generates the C2B5H7 dianion, which on treatment with tin dichloride yields... 

The reagent is prepared1 most conveniently in 80-88% yield by reduction of sulfur with sodium naphthalenide in THF (ultrasonic irradiation) to form Na2S in situ, which is then allowed to react with chlorotrimethylsilane. 

These systems are not catalytic in the true sense because solvolysis, with resultant destruction of the active species, is needed to liberate NH3. However, by controlled solvolysis followed by removal of the NH3, a further cycle of reduction, N2 absorption, and solvolysis often can be made. Titanium retains activity through about five such cycles in the tetra-isopropoxytitanium-sodium-naphthalenide system in ether using propan-2-ol for solvolysis (10). By using a nonprotic Lewis acid, aluminum tribromide, the catalytic effect of Ti is demonstrated. When N2 (100 atm pressure) is treated with a mixture of titanium tetrachloride, metallic aluminum, and aluminum tribromide at 130°C as much as 284 mol of NH3 per mol of TiCl4 is obtained after hydrolysis. This, then, is a system for the catalytic nitriding of Al (13). A similar system operating electrochemically yields 6.1 mol NH3 per g atom Ti in 11 days (14). 

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