Sodium methylate reagent

Sitosterol 206, 213, 242, 243 Sodium hydroxide reagent 395,408 Sodium methylate reagent 70 Solamargine 62 Solasodine 62 Solasonine 62 SoUdaginis, Extr. 279 Solvents 119ff... 

This sodium bisulphite reagent Is prepared by treating a saturated aqueous solution of sodium bisulphite with 70 per cent, of its volume (if rectified (or methylated) spirit, and then adding just sufiScient water to produce a clear solution. 

Cellobiose was prepared first by Skraup and Konig by the saponification of the octaacetate with alcoholic potassium hydroxide, and the method was improved by Pringsheim and Merkatz.3 Aqueous barium hydroxide also has been employed for the purpose, and methyl alcoholic ammonia has been used extensively for the hydrolysis of carbohydrate acetates. The method of catalytic hydrolysis with a small quantity of sodium methylate was introduced by Zemplen,i who considered the action to be due to the addition of the reagent to the ester-carbonyl groups of the sugar acetate and the decomposition of the addition compound by reaction with alcohol. The present procedure, reported by Zemplen, Gerecs, and Hadacsy, is a considerable improvement over the original method (see Note 2). 

Semmler and Mayer agree that the reagent used and the conditions of temperature, etc., govern the character of the sesquiterpene, or mixture of sesquiterpenes which result. By using sodium methylate very cautiously, they obtained a caryophyllene having the following characters —... 

Solvents and reagents are dried in the following fashion Benzene and ether are freshly distilled from sodium methyl iodide is distilled over calcium chloride and potassium hexa-chloroplatinate(IV) is dried at 110°. 

Use of the more expensive nitrosation reagent butylnitrite is successful when the reaction fails with the cheaper sodium nitrite reagent <2004JST23>. Introduction of a 15N label at the exocyclic nitrogen in compounds 45 where R = Me is achieved using the lsN-enriched l-phenyl-4-methyl-3-thiosemicarbazide formed from 15/V-methylamine... 

The synthesis of this substance was also effected by F. Smith.2 Methyl 6-trityl-a-D-galactopyranoside, in acetone solution, was treated six times with dimethyl sulphate and sodium hydroxide solution. The imperfectly methylated material thus obtained was then subjected to two treatments with methyl iodide and silver oxide. The necessity for so many treatments with methylating reagents emphasizes the difficulty of etherifying a glycoside substituted by the trityl radical in position 6. Subsequent to removal of the trityl radical, the methyl 2,3,4-trimethyl-(33) J. S. D. Bacon, D. J. Bell and J. Lorber, J. Chem. Soc., 1147 (1940). 

In the dehalogenation of 4-chlorobiphenyl, 1-chloro- and 1-bromonaphthalene, 9-chloro- and 9-bromoanthracene and 4-chlorobenzonitrile, diethyl sulphide has been used as electron donor397. The involvement of radical anions in these reactions is evidenced by the incorporation of deuterium into the products when the reactions were performed in acetonitrile-deuterium oxide. Lithium diisopropylamide in hexane or tetrahydrofuran398 and sodium methyl siliconate (MeSi03Na3)399 have also been used as electron transfer reagents in the photodehalogenation of 4-chlorobiphenyl. 

The data obtained also show that in going from sodium methylate and potassium hydroxide to lithium acetate, a reagent of relatively low nucleophilicity and comparatively high basicity, the intensity of side reactions of elimination is sharply reduced. 

ALKYNES Dimethyl sulfoxide-derived reagent (a). Sodium methyl-sulflnylmethide. 

By reaction with alkyl halides, esters of sulfonic and carbonic acids, trimethy-loxonium tetrafluoroborate, diazo compounds, Mannich or Mitsunobu conditions or miscellaneous reagents. Methyl iodide is a versatile and effective methylating reagent that can be used at room temperature, at moderate temperatures in a tightly closed vessel or at high temperatures in an autoclave. 2,4-Dihydropyrazol-3-one 1 was methylated at N1 with sodium hydride in boiling 1,4-dioxane followed by methyl iodide at room temperature. l,2-Dihydropyrazol-3-one 2 was obtained in 59% yield (79AP853) (Scheme 1). 

Problem (d) involves some of the same reagents as the first three syntheses. Ethyl iodide will be used in the place of methyl iodide. This reagent will add two carbons to the sodium methyl acetylide. 

Carr and Pyman (13) have shown that reduction of psychotrine (C26H26N2(0CH3)30H) with sodium and absolute ethanol gives rise to a mixture of cephaeline and isocephaeline by the addition of two hydrogens and when cephaeline is methylated with dimethyl sulfate and anhydrous sodium hydroxide or sodium amylate, it is mostly converted into emetine by 0-methylation. If however, dimethyl sulphate and sodium methylate are the reagents, the major product is iV-methylcephaeline with a little by-product iV-methylemetine. Psychotrine can be methylated to... 

The technical synthesis of cymoxanil [4] is rather straightforward. It starts, as described in Scheme 21.1, with the nitrosation of l-(2-cyano-acetyl)-3-ethylurea with sodium nitrite in water, followed by methylation of the oxime with a methylating reagent such as iodomethane. 

Knochel and co-workers have carried out a series of nucleophilic substitution reacion on ( )-allyl bromide using thiolate ions. The reaction between bromide 326 and lithium phenylthiolate yielded the ( )-sulfide 327 exclusively. However, treatment of ( )-sulfide 327 with the more nucleophilic reagent sodium methyl thiolate led to a 20 80 mixture of 327 and ( )-methyl sulfide 328. They proposed that either a S- 2 mechanism is operative, or two S- 2 substitutions eventually resulted in the thermodynamically more stable sulfide (ii)-methyl sulfide 328. A similar reaction of 326 with aniline in excess or its chloromagnesium amide gave a mixture of 5 n2 and 5 n2 products 329 and 330 which slowly equilibrate to give S-f 2 product 329 in 78% yield (Scheme 3.143). 

Other reagents that open the epoxide ring with substitution, to give the useful derivatives indicated in parentheses, include phenols (phenyl ethers) (81) y carboxylic acids (esters) (8 ), hydrogen sulfide in the presence of barium hydroxide (thiols) (82), sodium methyl mercaptide (methyl thio-ethers) (83), dipotassium hydrogen phosphate or dibenzylphosphoric acid (phosphate esters) (84), alkyl or aryl magnesium halides (halodeoxysugars)... 

Qrganolithiums react equally well but, in either case, two equivalents of the organometallic reagent were lequned one to deprotonate Ae inck dione and the second to react wiA the carbonyl. The deprotonation step could be avoided by utilizing the sodium salt of 2-cyano-l,3-indandione, 27a, as it was obtained m the cyclization of diethyl phthalate, sodium methylate and acetonitrile (. This sodium s t, in TEIF, reacted equally well with heterocyclic lithiums such as 2-lithiothiophene and S-lithiopyriniidine. 

The starting material for the preparation of these reagents is either 0- or p-aminophenyl-)8-galactoside or /3-laetoside, obtained by condensing the respective acetobromosugar with o- or p-nitrophenol, deacetylating with sodium methylate in methanol, and catalytic reduction in aqueous methanol. ... 

Sodium methylate, IN solution. Dissolve 54 g of the reagent in methanol and dilute to 1 liter with the same. Standardize against benzoic acid or other suitable standard. 

Sodium methylate, O.IN solution. Dilute 50 ml of the IN reagent to 500 ml with absolute methanol. 

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