F Dimethyl sulfate

Dimethylsilylmethyl)trimethyllead, 2605 f Dimethyl sulfate, 0929 f Dimethyl sulfide, 0932... 

When large groups, such as phenyl, bromo, ethoxycarbonyl or nitro are attached at position 3, the principal products are l-alkylcinnolin-4(l/f)-ones. Cyanoethylation and acetylation of cinnolin-4(l/f)-one takes place exclusively at N-1. Phthalazin-l(2/f)-ones give 2-substituted derivatives on alkylation and acylation. Alkylation of 4-hydroxyphthala2in-l(2/f)-one with an equimolar amount of primary halide in the presence of a base leads to 2-alkyl-4-hydroxyphthalazin-l(2/f)-one and further alkylation results in the formation of 4-alkoxy-2-alkylphthalazinone. Methylation of 4-hydroxy-2-methyl-phthalazinone with dimethyl sulfate in aqueous alkali gives a mixture of 4-methoxy-2-methylphthalazin-l(2/f)-one and 2,3-dimethylphthalazine-l,4(2//,3//)-dione, whereas methylation of 4-methoxyphthalazin-l(2/f)-one under similar conditions affords only 4-methoxy-2-methylphthalazinone. 

Dimethyl sulfate, reaction with di-methylformamide, 47, 52 Dimethyl sulfoxide, in synthesis of phenyl f-butyl ether, 45, 89 potassium salt, preparation, 48, 109, 110... 

Interestingly, deprotonation of the 3-oxo-pyrrolo[l,2-f]oxazole 277 with r-BuLi at —78°C took place at the C-5 position. Addition of an electrophile provided the substituted products 278 in good yields. Stannyl and silyl chlorides, dimethyl sulfate, ketones, and benzaldehyde were successfully used as electrophiles. A significant feature of this lithiation-substitution reaction is the generally high Ar-diastereoselectivity only single diastereomers of products were isolated (Scheme 41) <2001JA315>. 

Electrophilic substitution reactions of thieno[3,2-d]pyridine occur at position 7 (equation 38). With dimethyl sulfate in an alkaline medium, thieno[3,2-[Pg.1021]

Alkylation of 2/f-3-substituted 4-hydroxy-5,7-dimethylpyrido[3,2- ][l,2]thiazine 1,1-dioxide with alkyl halides or dimethyl sulfate afforded the Af(2)-methyl derivatives (86FES819, 86FES892,... 

Problem 13.51 Inorganic acids such as H2S04, H3P04, and HOC1 (hypochlorous acid) from esters. Write structural formulas for (a) dimethyl sulfate, (b) tribenzyl phosphate, (c) diphenyl hydrogen phosphate, (d) f-butyl nitrite, (e) lauryl hydrogen sulfate (lauryl alcohol is n-C ]H23CH2OH), (/) sodium lauryl sulfate. ... 

Rather surprisingly 2,4,6-triphenyl-4/f-thiopyran (74) is oxidized to the corresponding thiopyrylium 9 by alkylating agents, such as methyl iodide, dimethyl sulfate, and triethyloxonium fluoroborate (62JA2090). 

Pyrimido[4,5-d]pyrimidine-4-thiones are also formed by reaction of pyrimido[4,5-phosphorus pentasulfide. Methylation of these thiones with dimethyl sulfate or methyl iodide gives the corresponding methylthio derivatives (60JA5711). 5-Amino-l,3-dimethyI-7-methyIthiopyrimido[4,5-rf]pyrimidine-2,4(l//,3//)-dione (121) undergoes... 

Furthermore, the orientation of alkylation can be directed by the nature of the substituents. 4-Phenyl-l//-l,2,3-triazole (134) reacts with dimethyl sulfate to give the 1-methyl (135) and 2-methyl isomers (136) in 62% and 38% yield, respectively. The hindered l-methyl-5-phenyl derivative was not formed (67LA(707)147). C-Methylation of 1-phenyl-1/f-l,2,3-triazole can be carried out with butyllithium and methyl iodide at low temperatures (71CJC1792). 

Almost no 9,10-diaIkoxyphenanthrenes are known, and the quantities of those few made by other methods are either small or unstated. The best alternative procedure gave 9,10-dimethoxyphenanthrene when 9,10-phenanthrenequinone was combined first with sodium in diglyme and then with dimethyl sulfate, but the yield after two chromatographic purifications was 51 %. The only other reported alkylations of phenanthrene-9,10-diol are by 1-chloro-2-diethylaminoethane in 10% yield, f and by l,2-di(bromomethyl)benzene in 22% yield. s Unlike the procedure recorded here, none of these employ two-phase alkylations catalyzed by phase transfer agents." ... 

Dithioesters can be reduced in anhydrous acetonitrileor in methanol,the best results being obtained with dimethyl sulfate as alkylating agent. The most convenient procedure involves a simple electrolysis cell with a lead cathode and methanol as solvent. Eight substrates (68 X = SMe) were tested, with R equal to phenyl, chloro- and methoxy-substituted phenyls, and f-butyl. Unlike the corresponding reductions of thioamides, the reactions were not entirely clean and gave substantial amounts of side products such as (70). The product dithioacetals (69 X = SMe, R = Me) were formed in yields of 40-60%. On two of the substrates, better yields (ca. 70%) could be obtained in anhydrous acetonitrile, but a more sophisticated apparatus was required. One enolizable substrate (71) was tested, but the yield was only 30%. ... 

Pyridazines (56) are reduced by treatment with a mixture of dimethyl sulfate (which forms the corresponding salts in situ) and sodium borohydride to yield 1,6-dihydropyridazines (57 R = Me), together with minor amounts of 1,4,5,6-tetrahydropyridazines (58 R = Me). Normally 1,6-dihydropyrazines are unstable and decompose in air, but N-acylated derivatives are more stable. Thus if methyl chloroformate replaces dimethyl sulfate in the reaction mixture both 1,4-dihydro- (59 R = C02Me) and 1,6-dihydro-pyridazines (57 R = COjMe) can be isolated, the latter predominating if there is an electron-withdraw-ing group at C-6 in the starting material (Scheme 2)f ... 

At ordinary temperatures (68 F.), its volatility is only 3.3 mg. i>er liter, which i.< low for a lung injurant but high for a vesicant. Dimethyl sulfate is very readily dccompo.scd by water so that its vapors quickly combine with moisture in the air to form sulfuric acid. ThU is one of the chief d( fect.s of this substance as a chemical agent. 

The f-butyl ester is a relatively hindered ester and many of the methods reported below should be, and in many cases are, equally effective for the preparation of other hindered esters. The related 1- and 2-adamantyl esters have been used for the protection of aspartic acid and other amino acids (1-AdOH, toluene, dimethyl sulfate, cat. 

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