Sodium hydroxide , as base

The solution is prepared by dissolving 22.3 g (105 mmol) of potassium phosphate (Nakarai Chemicals, Japan) in water and adjusting the final volume to 35 mL. The original method5 used sodium hydroxide as base potassium phosphate is desirable for the extension of the present procedure to base-sensitive compounds. Under such conditions, the reaction with 9-(10-carbomethoxydecanyl)-9-BBN proceeds similarly without saponification of the ester group. 

The Sonogashira reaction of 2-iodothiophene with 2-methyl-3-butyne-2-ol or trimethylsilylacetylene under phase transfer conditions using sodium hydroxide as base led to the formation of the expected products, which released their end group spontaneously under the applied conditions giving rise to the intermediate formation of 2-ethynylthiophene. This terminal acetylene, in turn, reacted with another molecule of aryl halide, yielding either non symmetrical or symmetrical diarylethynes. When 2-methyl-3-butyn-2-ol was used as acetylene equivalent68 it was possible to introduce a benzothiophene moiety in the second step, while the reaction of 2-iodothiophene and trimethylsilylacetylene led to the formation of l,2-bis(2 -thienyl)acetylene (6.47.),69... 

BOC-Amino acids. Chemists at Fluka- have prepared many of these useful derivatives of amino acids by reaction with this reagent in aqueous organic solvents with sodium hydroxide as base. In general yields arc 65 -95%. 

The alkylation of the 1,2,6-thiadiazine (76) has been studied in detail (82H(l7)40l) because of its importance as an isostere of 6-methyluracil. Dimethyl sulfate in the presence of sodium hydroxide as base gives the 2-monomethyl derivative exclusively. Other reagents such as diazomethane and iodomethane give the 2,6-dimethyl derivative as the major product although substantial amounts of O-methylation and C-methylation at C-4 also occur, indicating that in systems where there are several possible sites for alkylation, the results are very much dependent on the reaction conditions. 

In polyfluorobenzenes having other substituents in addition to fluorine, including per-fluoroalkyl or perfluoroaryl groups, the elimination of only one fluorine atom proceeds more readily, with the para position in pentafluorobenzene derivatives being replaced first. The reaction conditions used for monosubstitution of fluorine depend markedly on the substrate and on the nucleophilic agent chosen. In most cases the reaction can be carried out in ethylene glycol/pyridine using sodium hydroxide as base (Table 3). 

Multiple, but not complete, substitution of fluorine by sulfur nucleophiles proceeds under conditions rather similar to those for single elimination, i.e. generally in diethylene glycol/ pyridine mixture with sodium hydroxide as base, but with an increased molar ratio of the respective thiol, corresponding to the number of fluorines to be eliminated. On reaction in ethylene glycol/ pyridine, rather than in dimethylformamide or, particularly, in hexamethyl-phosphoric triamide, at least two fluorine atoms remain in the molecule, even under drastic... 

The successful extension of this asymmetric reaction to the use of allyl halides (instead of benzyl halides) was also reported by the Metzner group [208]. The desired vinyl oxiranes were formed in a one-pot reaction starting from an allyl halide and an aromatic aldehyde in the presence of a sulfide, e.g. 215, and sodium hydroxide as base. A 9 1 mixture of tert-butanol and water was used as solvent. 

A new cyclization process was published in 2003 <2003PS1295>, where dithiols are substituted by dithioiminium salts, which can be created by reacting thioacteamide 5 with a,o -dihalides. In a second step, the dithioiminium salts 6 are treated with (different) a,tu-dihalides adding sodium hydroxide, as base, and tetrabutylammonium bromide, as phase-transfer catalyst (Scheme 2). Thus, two kinds of macrocycles are found in the final reaction mixture XS2 (1 1 ratio) 7 and (2X)S4 (2 2 ratio) 8. 

Alkylation of aldehydes and -keto esters, This reaction can be conducted by use of solid-liquid phase-transfer catalysis using powdered sodium hydroxide as base and benzene as the solvent. Under these conditions aldehydes with only one a -hydrogen, such as isobutyraldehyde, are alkylated in reasonable yield even by less reactive halides (equation I). 

The chemistry of sulfones is dominated by the reactions of sulfonyl carbanions. The sulfone group has a unique ability to facilitate deprotonation of attached alkyl, alkenyl and aryl groups and will permit multiple deprotonation to yield polyanions. These properties, combined with the relative intertness of the sulfone (S02) group to nucleophilic attack, have made the S02 group the first choice for stabilisation of carbanions and account for the extensive application of sulfones in synthesis. Sulfonyl carbanions can be generated and reacted under a wide variety of conditions extending from aqueous phase transfer reactions using sodium hydroxide as base to the use of alkyllithiums in polar aprotic solvents. The reactivity of sulfonyl carbanions depends on the nature of the metal counterion (Li+, Na+, K+ and Mg2+ are the most important ones) and the presence of additives, e.g. TMEDA, HMPA and Lewis acids. 

I roccdiircs for the conversion of isophoronc" (71 and 2,3-diphenylindenitn (HI into (he corresponding epoxides specify sodium hydroxide as base and methanol ur oihunol ns orgiinic sulvcnt. 

Permethylation of polysaccharides. Kuhn and Trischmann found that polysaccharides can be methylated very efficiently in DMSO with dimethyl sulfate and barium oxide and/or barium hydroxide. Srivastava et al. used the same method except for the substitution of sodium hydroxide as base. Sodium hydroxide pellets and dimethyl sulfate were added with stirring under nitrogen over 8 hrs. to a solution of undegraded stareh in dimethyl sulfoxide. After stirring for another 16 hrs. the mixture was heated to decompose the dimethyl sulfate, cooled, diluted, and neutralized, and the product was extracted with chloroform and precipitated from acetone with ether yield 91%, OCHa = 42.3%. Here the high solvent power of DMSO clearly contributes to the solvent effect. 

A bicyclic aromatic ring system provides additional stabilization of the anionic a-adducts hence, nitronaphthalene derivatives show good reactivity in the VNS hydroxylation. 1-Nitronaphthalenes give 2- and 4-hydroxy derivatives in high yields. The orientation of the hydroxylation depends on the kind of base. For instance, treatment of 1-nitronaphthalene (15) with f-butyl hydroperoxide and potassium t-butoxide affords l-nitro-2-naphthol (16) whereas using sodium hydroxide as base gives 4-nitro-l-naphthol (14) (equation 34) . 

Dichlorocyclopropanes have been converted to l,l-bis(phenylsulfanyl)cyclopropanes in good yield under phase-transfer conditions using sodium hydroxide as base, benzene as organic solvent, and tetrabutylammonium bromide or benzyltriethylammonium chloride as catalyst. Typically, ler/-butyl 2,2-bis(phenylsulfanyl)cyclopropanecarboxylate (3) was obtained in 71 /o yield from tert-butyl 2,2-dichlorocyclopropanecarboxylate by this method. ... 

Methylation of aryl thiols. PTC methylation of l C-aryl thiols with methyl Iodide (2 ) Is very useful for microscale synthesis of C-labeled aryl methyl sulfides (2j ). The reaction, using tetrabutylammonlum hydrogensulfate as catalyst and sodium hydroxide as base In methylene chloride and water, proceeds at ambient temperature In 50-100Z yield. 

The precursor aryl-malonamide 21 is prepared in a three-step procedure from 2,6-diethyl-toluidine. A technically feasible cross<oupling reaction has been developed for the synthesis of aryl malononitrile 20 starting from benzene derivative 19 and malononitrile. The optimized procedure with PdQ2/tricyclo-hexylphosphine and sodium tert-butoxide as base in refluxing xylene [81] was improved even further using palladium dichloride/triphenylphosphine as catalyst and sodium hydroxide as base in l-methyl-2-pyrrolidone at 125-130 °C [82]. The aryl-malononitrile 20 is hydrolyzed to the aryl-malonamide 21 in cone, sulphuric acid. 

Three further computational explorations of carbene reaction mechanisms have been reported. DFT study of the Reimer-Tiemann reaction (formal reaction between CCl2 and a phenoxide ion) using either potassium or sodium hydroxide as base has revealed that the active carbenic species is an alkaline carbenoid form rather than its free form as suggested earlier. DFT study of the reaction of CHF with dioxygen has confirmed fhaf fhe firsf step involves formation of the planar HFCO2 adduct. The initial steps of 2,5-dimethylfuran thermal decomposition have been computationally identified as scission of the C—H bond in the methyl side chain and subsequent formation of ft- and a-carbenes (39) and (40) via [3,2]-H and [2,3]-methyl shifts, respectively (Scheme 6). Once generated, carbenes (39) and (40) are believed to follow diverse fragmentation pathways. ... 

Dimethyl sulfoxide is generally favored, particularly with processes using sodium hydroxide as base. In carbonate polymerizations, the presence of free phenolic hydroxyl groups at polymerization temperatures of 150-160°C leads to undesirable side reactions Involving acid catalyzed decomposition of OMSO which ultimately can lead to stoichiometry upsets. For polymerizations involving carbonate, dimethyl acetamide is often the solvent of choice [7], DMSO is limited by its 180 C boiling point to temperatures of 170 C or lower while DMAc is useful in the 150-160 C range. 

The phenylhydrazones of a number of aldehydes and ketones were found to alkylate in a two-phase system using 50% aqueous sodium hydroxide as base and tetrabutylammonium chloride as catalyst. Exclusive A-alkylation is observed in 43—98% yield for the thirteen examples reported. 

Reactions.—A-Alkylation of acetanilides has been achieved using a two-phase system of water and benzene with sodium hydroxide as base and triethylbenzylam-monium chloride yields are better than 80%. An efficient two-step process for the A-methylation of unsubstituted amides, lactams, and ureas has been described which involves initial formation of the corresponding methylol, by treatment with formaldehyde, followed by reduction with either triethylsilane and trifluoroacetic acid or with hydrogen over palladium in TFA. A method for the methylthiomethy-lation of both amides and lactanes has appeared. ... 

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