Sodium in xylene

Butyroin has been prepared by reductive condensation of ethyl butyrate with sodium in xylene, or with sodium in the presence of chloro-trimethylsilane. and by reduction of 4,5-octanedlone with sodium l-benzyl-3-carbamoyl-l,4-dihydropyridine-4-sulfinate in the presence of magnesium chloride or with thiophenol in the presence of iron polyphthalocyanine as electron transfer agent.This acyloin has also been obtained by oxidation of (E)-4-octene with potassium permanganate and by reaction of... 

Bis(trimethylsiloxy)cyclobutene, a very useful building block, is easily prepared by the modified acyloin condensation of diethyl succinate with sodium in xylene in the presence of trimethylsilylehloride 62). 

Alkyl alkanoates are reduced only at very negative potentials so that preparative scale experiments at mercury or lead cathodes are not successful. Phenyl alkanoates afford 30-36% yields of the alkan-l-ol under acid conditions [148]. Preparative scale reduction of methyl alkanoates is best achieved at a magnesium cathode in tetrahydrofuran containing tm-butanol as proton donor. The reaction is carried out in an undivided cell with a sacrificial magnesium anode and affords the alkan-l-ol in good yields [151]. In the absence of a proton donor and in the presence of chlorotrimethylsilane, acyloin derivatives 30 arc formed in a process related to the acyloin condensation of esters using sodium in xylene [152], Radical-anions formed initially can be trapped by intramolecular addition to an alkene function in substrates such as 31 to give aiicyclic products [151]. 

Dieckmann cyclizations of diesters of type (210) are catalyzed by potassium f-butoxide in toluene, sodium in xylene, or sodium hydride in DMF, and produce 1-benzazepinones in good yields. The method is also applicable to the synthesis of azepines fused to other heterocycles, e.g. pyrrolo[2,3-6]azepin-4-ones (211) (81H(16)399). 

Ethyl /3,/3-pentamethyleneglycidate has been prepared in 65% yield by the condensation of cyclohexanone with ethyl chloro-acetate in the presence of sodium ethoxide,4 and in 50% yield in the presence of sodium in xylene.6 The present procedure employs potassium (erZ-butoxide as the condensing agent.3... 

A laboratory preparation of the simplest of these catenation compounds. two interlocking rings, has been carried out at AT T Bell Laboratories. They started wilh the dimethyl ester of a 34-carbon paraffinic dicarboxylic acid, CH ,OOC-(CH )j2-COOCHi, which was reacted in a suspension of metallic sodium in xylene with acelic acid to condense the terminal ester groups to form an aceloin ring compound. 

The so-called acyloin condensation consists of the reduction of esters—and the reduction of diesters in particular—with sodium in xylene. The reaction mechanism of this condensation is shown in rows 2-4 of Figure 14.51. Only the first of these intermediates, radical anion C, occurs as an intermediate in the Bouveault-Blanc reduction as well. In xylene, of course, the radical anion C cannot be protonated. As a consequence, it persists until the second ester also has taken up an electron while forming the bis(radical anion) F. The two radical centers of F combine in the next step to give the sodium glycolate G. Compound G, the dianion of a bis(hemiacetal), is converted into the 1,2-diketone J by elimination of two equivalents of sodium alkoxide. This diketone is converted by two successive electron transfer reactions into the enediolate I, which is stable in xylene until it is converted into the enediol H during acidic aqueous workup. This enediol tautomerizes subsequently to furnish the a-hydroxyketone—or... 

The iodide when treated with sodium in xylene solution gives sodium iodide and the unsaturated silicohydrocarbon. With magnesium ethyl bromide, the iodide yields octaphenyldiethylsilico-ietrane which crystallises from aqueous acetone containing a little chloroform in flat, transparent, rhomboidal plates, containing 3 mols, of water of crystallisation. When anhydrous, it melts at 253° to 254° C. when heated with piperidine and sodium hydroxide, it decomposes with evolution of hydrogen. ... 

Germanium dimethylanilino triphenyl, (CPl3)2NCeH4.Ge(CeH5)3, from triphenyl germanium bromide, p-bromodimethylaniline, and sodium in xylene, forms brownish, crystalline nodules, M.pt, 140° to 141° C. The hydrochloride melts with decomposition at 105° to ll6° C., is insoluble in water and hydrochloric acid, but soluble in alcohol. When treated with alkali it gives the pure, free base. 

Acyloin condensation (2, 435-436). Japanese chemists3 have extended Bloomfield s procedure for ring enlargement of cycloalkane-1,2-dicarboxylie esters. Thus the esters (1) were treated with sodium in xylene at 110-120° in the presence of trimethylchlorosilane and the reaction mixture refluxed to ensure ring opening of the cyclobutenes (2) to 1,3-dienes (3). Acidic hydrolysis gave 1,2-diketones (4) in 71 -74% yields. These can be reduced to acyloins (5) by alkaline hydrolysis with triethyl phosphite (74-79%). 

High yields of cyclobutane derivatives are obtained from the bis-p-toluene-sulfonates of 1,3-diols, as is shown by the synthesis of diethyl dispiro[3.1.4.1 ]-undecane-2,2-dicarboxylate from 2,2-spiro [3,4]octanebis(methyl /7-toluene-sulfonate) and ethyl malonate (warming with sodium in xylene) 386... 

Adams (245). Ethyl j8-(3-carbethoxypiperidine)-propionate (XLVII) is converted by the action of sodium in xylene into ethyl isogranatonine-carboxylate (XLVIII) which is reduced to the corresponding alcohol (XLIX, R = H). The benzoyl derivative of this alcohol (XLIX, R = CeHsCO) is closely related to cocaine in structure. 

In one case a discrete polymer, dodecamethylcyclohexatin, has been obtained 211) from the reaction of dimethyltin dichloride with sodium in liquid ammonia. Using diorganotin dichlorides and sodium in xylene, a,co-dichloropolytin compounds may be obtained in yields of up to 50% 212). One major product was obtained from each tin halide dimethyltin dichloride produced a ditin diethyl-, dipropyl-, and dibutyltin dichloride gave tetratin, tritin, and pentatin, respectively 212). 

Full details have been published on the oxidative rearrangement of pyruvates to malonates. Whereas the reduction of dimethyl bismethylmalonate with sodium in xylene is reported to yield the keten acetal (9) in the presence of trimethylchlorosilane, when the solvent is ammonia a mixture of products is formed, including the cyclopropanediol di(trimethylsilyl)ether (10). This diol, on treatment with sodium methoxide, gives the products shown in Scheme 39, possibly by Cannizzaro disproportionation of the aldehyde (11). The mechanism of decarboxylation of monoethyl oxaloacetate has been studied as part of a general investigation of ) -keto-acid decarboxylation. 

Cyclization of (33 n = 12 —40, R = H or Me) with sodium in xylene and trimethylsilyl chloride gives the acyloins (34 n = 12—40), which are further converted into cyclic hydrocarbons and thence into catenanes. Cyclizations of (35 6 < n < 12) are also reported. ... 

The dechlorination of dimethyldichlorosilane can be effected using sodium in xylene to give a linear polysilane. This polymer is better suited for conversion to poly(carbosilane) than is dodecamethylcyclohexasilane since the reaction product of pyrolysis requires a far less complex purification process to give a polymer suitable for spinning. 

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