Sodium alkoxides preparation

The sodium alkoxides prepared from primary and secondary alcohols and sodium hydride in a mixture of THF and DMF or DMSO react with p-methoxy-benzyl chloride at room temperature to give the p-methoxybenzyl ethers in good yield. Use of THF alone is not so satisfactory. p-Methoxybenzyl chloride (nip -1 °C bp 117 C/L9 kPa) is moisture sensitive and deteriorates on standing so it should be freshly distilled in vacuo before use. In sluggish reactions, the rate can be increased by the addition of a catalytic amount of tetrabutylam-... 

Figure 15.3 Experimental setup used for sodium alkoxides preparation. 1. Magnetic stirrer, 2. Reaction vessel, 3. Moisture trap with silica gel, 4. Gas bubbler and 5. Thermostat.

Mixed ethers may be prepared by the interaction of an. alkyl halide and a sodium alkoxide (Williamson s synthesis), for example ... 

A benzyl carbonate was prepared in 83% yield from the sodium alkoxide of glycerol and benzyl chloroformate (20°, 24 h). It is cleaved by hydrogenolysis (H2/ Pd-C, EtOH, 20°, 2 h, 2 atm, 76% yield) and electrolytic reduction (-2.7 V, R4N X, DMF, 70% yield). A benzyl carbonate was used to protect the hy-droxyl group in lactic acid during a peptide synthesis. 

Usually metal-free phthalocyanine (PcH2) can be prepared from phthalonitrile with or without a solvent. Hydrogen-donor solvents such as pentan-l-ol and 2-(dimethylamino)ethanol are most often used for the preparation.113,127 128 To increase the yield of the product, some basic catalyst can be added (e.g., DBU, anhyd NH3). When lithium or sodium alkoxides are used as a base the reaction leads to the respective alkali-metal phthalocyanine, which can easily be converted into the free base by treatment with acid and water.129 The solvent-free preparation is carried out in a melt of the phthalonitrile and the reductive agent hydroquinone at ca. 200 C.130 Besides these and various other conventional chemical synthetic methods, PcH2 can also be prepared electrochemically.79... 

The organotin alkoxides RgSnOR and R2Sn(OR >2 can be prepared by treating the appropriate organotin chlorides with sodium alkoxides, and this procedure has been extended to the preparation of the monoal-kyltin trialkoxides, RSnCOR la (190), which serve as useful reagents for the synthesis of other monoalkyltin derivatives. Alternatively, the trialkoxides can be prepared by alcoholysis of the tris(amino) compounds RSn(NR )3 (191). 

The overall sequence of three steps may be called the Wittig reaction, or only the final step. Phosphonium salts are also prepared by addition of phosphines to Michael alkenes (hke 15-8) and in other ways. The phosphonium salts are most often converted to the ylids by treatment with a strong base such as butyllithium, sodium amide, sodium hydride, or a sodium alkoxide, though weaker bases can be used if... 

The nucleophilic vinylic substitution reaction of ( )-a-haloenyne sulfones with sodium alkoxides proceeds regioselectively to give ( )-a-alkoxyenyne sulfones. These conqioimds are versatile intermediates for the preparation of iiirans (Scheme 15, <96TL7381>). 

The sodium salt of an alcohol (a sodium alkoxide) can be prepared by treating an alcohol with sodium metal ... 

Sodium alkoxides can also be prepared by reacting an alcohol with sodium hydride (H ) ... 

Fewer routes are known for the preparation of dithiophosphonic acids. Nevertheless sodium dithiophosphophonates have been prepared in high yields from reaction of dithiadiphosphetane disulfides with a sodium alkoxide or aryloxide in the corresponding alcohol solution (Equation 25).40,41... 

Methyloxindole has been prepared by the reduction of a-(2-nitro-phenyl)propionic acid,2 by heating j8-propionylphenylhydrazine with lime3 or with sodium alkoxides,4 and by reduction of the benzoyl derivative of oxindole-3-aldehyde.6... 

Notes ° Unless otherwise noted, sodium alkoxides (1.25-2.5 equiv) prepared in situ from the corresponding alcohols with NaH in THF were allowed to react with CICH2SPh (1 equiv) and t-BuOK (equivalent to alkoxides) for the period indicated. b All products showed satisfactory spectra I data (IR,1H NMR, and mass). c Yields refer to the isolated yield based on CICH2SPh. d Satisfactory analytical results were obtained for these compounds. ef-BuONa (2.5 equiv) was employed in place of t-BuOK. f [3.3-dimethyl-2-(phenylthio)cydopropyl]methanol (mixture of isomers). BCH2=C=CHOCH2SPh. 

Furthermore, the preparation and reactions of 2-methoxythiophene were studied by Sice (70). This compound was obtained by a copper catalysed Williamson synthesis. It was also found that iodothiophene reacted readily with sodium alkoxides, whereas bromothiophene reacted slowly and chlorothiophene did not react at all. Sodium iodide accelerated the reaction of bromothiophene. The ortho, para orienting alkoxy group on carbon atom 2 increased the directive influence of the sulphur atom to the 5 position but competed with it to induce some attack on the 3 position by electrophilic reagents (nitration, acylation). The acylation of 2-methoxythiophene with stannic chloride at low temperatures furnished a mixture of two isomers. The 5-methoxy-2-acetothienone was obtained in higher yield and was identified by its ultraviolet absorption spectrum. 

Using this base (Na0Me/A1203) methyl phenylaceteate was obtained in 74 percent yield. Also, other esters, such as isobutyl phenylacetate, could be prepared by reaction in the appropriate solvent (isobutanol, 67 percent yield) using the sodium alkoxide on alumina reagent(45). 

For rhodium and iridium compounds alkoxo ligands take over the role of the basic anion. Using /z-alkoxo complexes of ( -cod)rhodium(I) and iridium(I)— formed in situ by adding the /r-chloro bridged analogues to a solution of sodium alkoxide in the corresponding alcohol and azolium salts—leads to the desired NHC complexes even at room temperature [Eq. (10)]. Using imidazolium ethoxyl-ates with [(r " -cod)RhCl]2 provides an alternative way to the same complexes. By this method, it is also possible to prepare benzimidazolin-2-ylidene complexes of rhodium(I). Furthermore, an extension to triazolium and tetrazolium salts was shown to be possible. ... 

Bornene has been prepared from the reaction of 2-bromo-bornane-3-carboxyIic acid with aqueous sodium bicarbonate,6 by pyrolysis of isoborneol methyl xanthate,7 and by the j8-elimination of hydrogen chloride from bornyl chloride with sodium alkoxides in various solvents.2... 

In 1962 Gompper, Kutter, and Topfl prepared substituted thieno-thiophenes (1) from dithiocarboxylate s ts. With haloacetic acid derivatives these give ketenemercaptals (104), which are easily converted by base into 3-amino- and 3-hydroxythiophenes (105). Further cyclization of 105 results in substituted thienotMophenes 106, which may also be obtained directly by heating the dithiocarboxylates with haloacetic acid derivatives in alcoholic sodium alkoxide (Scheme 7). 

Although there have been few new developments in the period since 1993, halogenopyrazines 42 have been convenient precursors for a variety of pyrazine derivatives. For example, the halogenopyrazines 42 are cyanated by palladium-catalyzed cross-coupling with alkali cyanide or by treatment with copper cyanide in refluxing picoline, to yield cyanopyrazines 48. Alkoxypyrazines 49 are produced by treatment with alkoxide-alcohol, and aminopyrazines 50 are prepared by amination with ammonia or appropriate amines. The nucleophilic substitution of chloropyrazine with sodium alkoxide, phenoxide, alkyl- or arylthiolate is efficiently effected under focused microwave irradiation <2002T887>. 

The starting 2-(l-alkoxynaphth-2-yl)-4,5-dihydro-4,4-dimethyl-l,3-oxazoles are prepared by treatment of the bromo-4,5-dihydro-l,3-oxazole derivative with sodium alkoxide in DMF at 50 °C, or by transesterification reactions in which the methoxy-4,5-dihydro-l,3-oxa7ole derivative is heated with the appropriate chiral alcohol/chiral sodium alkoxide mixture29. 

Preparation of Pseudoureas by the Reaction of Cyanamides with Alcohols6 in the Presence of Sodium Alkoxides... 

The original method of preparation involved reaction of the sodium alkoxide and titanium tetrachloride in the appropriate alcohol, as shown by equation (13). However, this is slow and only works for those alcohols which readily form sodium alkoxides. An improved method is shown by equation (14). If a proton-accepting reagent, such as ammonia, is not employed, however, the reaction proceeds only as far as the TiCl2(OR)2 derivative. 

The sodium alcoholate of cellulose prepared from a sodium alkoxide is probably similar to, if not identical with, that prepared from sodium hydroxide. Monomethylation of the alcoholate prepared with either sodium methoxide or sodium l-butoxide140 occurs preferentially at the hydroxyl groups on C-2 and C-6. Very little methylation occurs at the hydroxyl group on C-3. 

Coupling of 1-alkenylboranes with 1-bromoalkenes or -alkynes.4,s This reaction fails when catalyzed by Pd(0) alone, but proceeds in high yield in the presence of an added sodium alkoxide or sodium hydroxide in refluxing benzene (or THF). This coupling can be used to prepare (E,E)-, (E,Z)-, (Z,E)-, or (Z,Z)-1,3-dienes stereo- and regiospecifically. 

Benzylidene triphenylarsoranes have been prepared in situ from their corresponding salts, either with butyl- or phenyllithium in ether (5.5, 76) or with sodium alkoxide in alcohol (97). Carbomethoxybenzylidene triphenylarsorane (3) has been prepared from the corresponding salt in chloroform with ammonia (74). With the same method or with sodium alkoxide in alcohol, acetylmethyl-, phenacyl-, and carbomethoxymethyl-triphenylarsonium salts afforded the corresponding ylides (28, 48, 70, 73, 74, 94). 

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