Methylation with dimethylsulfate

The 2-methylthio-3-substituted quinazolin-4(3H)-one 3 was obtained by dissolving 4 in 2% alcoholic sodium hydroxide solution and methylating with dimethylsulfate whilst stirring at room temperature (yield 88%, m.p 124-126 C). The IR spectrum of 3 showed the disappearance of the amino (NH) and thioxo (CS) stretching signals of the starting materials. It showed a peak for carbonyl (CO) stretching at 1680 cm The NMR spectriun of com-... 

Further reactions of dimethylamide 6c lead to interesting chiral molecules. 0-Methylation with dimethylsulfate followed by LiAlH4 reduction of the amide carbonyl furnishes —)-2-methoxy-A,ALdimethylpropylamine (8) in high yield [6]. 

AG(E)508> of -l,2-bis(tri-/i-butylstannyl)ethylene with a 2-iodo-3-substituted thiophene affords monomer (147) <93SM1188>. When 2,5-diiodothiophene derivatives are used, the polymer (148) is obtained directly <93MI 212-12, 93SM1255>. Thiophene-2,5-dicarbaldehyde can also be subjected to benzoin condensation conditions to afford (149) after methylation with dimethylsulfate <93MI 212-13>. 

The immobilization of amino-3-CD and amino-methylated-g-CD on PW gel v/as carried out. Amino-CD gel (ACD-PW) was obtained by the procedure with the epoxyl bead gel and 6-monoazide- g-CD which was prepared by regiospecific tosylation and substitution by sodium azide. The obtained monoazide-g-CD gel was treated with triphenylphosphin in DMF, then with ammonium hydroxide which gave amino-g-CD gel(ACD-PW). Araino-methyl-g -CD gel(A-Me-CD-PW) was prepared starting with the 6-monoazide-g-CD gel. The gel was methylated with dimethylsulfate in the mixed solvent of chloroform and an aqueous sodium hydroxide solution with shaking at room temperature for 72 hrs. Monoazide-methyl-g-CD gel... 

Alcoholic groups are also able to form ethers. The hemiacetal hydroxyl group on C-1 is unusually reactive compounds derived from it are called glycosides. A separate chapter is devoted to them (Chapt. XVII). Ether formation (e.g. methylation with dimethylsulfate and alkali) is also important for the constitutional determination of oligosaccharides. 

Diazepam From a chemical point of view, diazepam, 7-chloro-l,3-dihydro-l-methyl-5-phenyl-2H-l,4-benzodiazepin-2-one (5.1.2), is the most simple of all of the examined derivatives of l,4-benzodiazepin-2-ones. Various ways for the synthesis of diazepam from 2-amino-5-chlorobenzophenone have been proposed. The first two ways consist of the direct cyclocondensation of 2-amino-5-chlorobenzophenone or 2-methylamino-5-chlorobenzophenone with the ethyl ester of glycine hydrochloride. The amide nitrogen atom of the obtained 7-chloro-l,3-dihydro-5-phenyl-2H-l,4-benzodiazepin-2-one (5.1.1), is methylated by dimethylsulfate, which leads to the formation of diazepam (5.1.2). 

Trimethadione Trimethadione, 3,5,5-trimethyloxazolidine-2,4-dione (9.8.2), is synthesized by methylating 5,5-trimethyloxazolidine-2,4-dione (9.8.1) with dimethylsulfate. 

Stereoselective reaction with ketones. The reaction of ketone 1 with methyl-lithium, trimethylaluminum, and lithium letramethylaluminate shows no stcrco-specificity. The reaction with mcthylmagncsium bromide gives the two possible adducts in the ratio 2.4 1. The best stereospccificity is observed with dimethylsulf-oxonium methylide, which converts 1 into 2 and 3 in a ratio about 5 1. Reduction of the epoxides with lithium triethylborohydride gives the desired tertiary alcohols. This reaction was used in a synthesis of ( ) stemodin (4).2... 

Solid-probe mass spectrometric analysis (31) showed that the benzene-ether extracts consist mainly of organic acids. Therefore, these extracts were deriva-tized with dimethylsulfate-de to yield methyl-da-labeled derivatives. The derivatives were analyzed by GCMS and high resolution MS using techniques that have been described previously (31). Authentic samples of phenolic acids deriva-tized with dimethylsulfate-dg or diazomethane were also analyzed by GCMS for reference. The distribution of the organic acids as methyl esters was determined by measuring areas of GC fiame ionization detector peaks with a correction for the effective carbon number for each compound. 

Methylation (78MI2) of 213 with dimethylsulfate in alkaline solution afforded the (V-methyl derivative 215, whose structure has the acyclic form. Attachment of the methyl group to the nitrogen rather than the oxygen atom was proved by IR spectroscopy, which showed a band corresponding to the OCN group, and by H-NMR spectra, which showed... 

Dimethylsulfate, Li0H-H20, THF, reflux, 66-100% yield. K2CO3 in acetone can effectively be used as base and solvent with dimethylsulfate to form esters. A polymer supported methyl sulfate also effectively esterifles carboxylic acids (K2CO3, CH3CN, reflux, 72-99% yield). This reagent also alkylates thiols, phenols, phosphates, and amines. ... 

Alkylisothiazolium salts 27,45 and 75 were prepared by N-alkylation of isothiazoles 74 with a very wide range of alkyl bromides and iodides, methyl -toluene-sulfonate, methyl trifluoromethansulfonate, methyl fluorosulfonate, dimethylsulfate... 

Monohalomethanes, CH3X (X = Cl, Br, I), do not react with BSD. If X is replaced by a more nucleophilic leaving group such as sulfate, that is, if BSD is treated with dimethylsulfate, then beside BSD thermolysis, a nucleophilic substitution of a silyl group of BSD by a methyl group takes place (29) [Eq. (62)]. 

Surface oxides on graphite undergo the reactions typical of carboxylic acids, phenols and alcohols. Methylation with diazomethane or dimethylsulfate, silanization of—OH groups by reaction with halosilanes, formation of acyl chlorides by reaction with thionyl chloride, further reactions of these acyl chlorides, neutralization of acidic surface groups with different bases, ion exchange and more special reactions are used to characterize surface oxides on carbon and to modify their properties for technical applications . 

Simple hydrolysis of natural DNA does not lead anywhere in analysis. If the acid hydrolysis is, however, preceded by base-modification reactions, one obtains Nobel prize-winning differentiations. This is documented in the simplified protocol developed by Maxam and Gilbert (Scheme 8.3.2). Dimethyl sulfate methylates guanine at N7 five times faster than N3 at adenine. None of the other bases reacts with dimethylsulfate if reaction times are kept short and the temperature low. Reaction conditions are selected in a way that only 1-2 % of the nu-cleobases react in a ratio of guanine adenine of 5 1. These bases are now... 

Pentachloropyridine and phosphorus pentasulfide give 4-mercaptotetrachloro-pyridine (XII-631), which can be methylated readily with dimethylsulfate in aqueous alkali. ... 

Edlbacher (126,127) studied the action of dimethyl sulfate on edestin and other proteins and concluded that mainly lysine NH, groups reacted. Those proteins which contained no lysine failed to react. He also isolated methyl -amino lysine from methylated casein (128). Haurowitz (129) has recently treated crystalline horse hemoglobin and egg albumin with dimethylsulfate and obtained as an upper limit 6.5% and 3.9%, respectively, of OCHg groups. This is 142 and 54 methoxyl groups per mole protein and represents a large proportion of the total ionizable groups for these two proteins (18). 

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