Dimethylformamide dialkyl acetals

Other alkylating agents which have been used include diazomethane [2], trialkyl phosphates [11], alkoxypho.sphonium salts [12], dimethylformamide dialkyl acetals [13], trialkyl orthoformates [14], alkyl cyanoformates [15], dialkyl carbonates (less toxic) [16] and, where more powerful reagents arc needed, alkyl fluorosulfonates, trialkyloxonium tetrafluoroborates [17], alky] triflates and mesylates [18, 19]. 

Glycosides. Glycosides can be prepared conveniently by reaction of peracyl derivatives of D-ribofuranose or D-glucopyranose with N,N-dimethylformamide dialkyl acetals under Lewis acid catalysis (equations I and II). Unlike classical methods, this new glycosidation method does not employ the unstable glycosyl halides. 

N,N-Dimethylformamide dialkyl acetals in mixture with pyridine can react with fatty acids in a hot GC injector to methylate fatty acids. However, the hydroxyl groups of HFAs do not react. 

Alkylation describes the reaction where an active hydrogen is replaced with an alkyl group, for example, a methyl group. Most polar groups can be alkylated, and many reagents can be used, for example, alkyl halogenides, diazo alkanes, and N,N -dimethylformamide dialkyl acetal. An example of an alkylation is the formation of methyl esters of fatty acids by using methanolic BF3, where boron trifluoride (BF3) acts as a catalyst. 

Thenot, J.-P., Horning, E.C., Stafford, M. and Homing, M.G. (1972), Fatty acid esterification with N,N-dimethylformamide dialkyl acetals for GC analysis. Anal. Lett., 5,217. 

Dimethylformamide and dialkyl-acetals (e.g., dibutylacetals) Alkyl (e.g., butyl) 270... 

The Batcho indole synthesis involves the conversion of an o-nitrotoluene to a (3-dialkyl-amino-o-nitrostyrene with dimethylformamide acetal, followed by reductive cyclization to indoles. This provides a useful strategy for synthesis of substituted indoles (Eq. 10.49).63... 

Treatment of diphenylacetonitrile in toluene with sodium amide and 2-chloro-pyrazine gave 2-(C-cyano-C,C-diphenylmethyl)pyrazine (1021), and 2-vinylpyrazine with phenylacetonitrile and sodium heated at 120-130° for 10 minutes gave 2-(3 -cyano-3 -phenylpropyl)pyrazine (731). 2-Amino-5-bromomethyl-3-cyano-pyrazine with sodium hydride and methyl cyanoacetate in tetrahydrofuran formed the dialkylated product (56) (1031). 2-Amino-3-mercapto-5,6-dimethylpyrazine in methanol with potassium hydroxide and chloroacetonitrile gave 2-amino-3-cyanomethyIthio-5,6-dimethylpyrazine (1229), and 2-carboxypyrazine refluxed with chloroacetonitrile and triethylamine in ethyl acetate for 45 minutes gave the cyanomethyl ester (1317). 2-Hydroxy 5-methyl-3-propylpyrazine with cyanogen halides in aqueous sodium hydroxide-dimethylformamide at 0-5° gave l-cyano-5-methyl-2-oxo-3-propyl-l, 2-dihydropyrazine (1123). 

Primary aromatic amines and their N-mono- and N,N-dialkyl derivatives can be coupled with diazonium salts in a slightly acid medium. The reaction can be carried out using stabilized diazonium salts (which do not contain free nitrous acid), for example, with p-nitrobenzenediazonium fluoroborate (17) or with a salt with 1-naphthalenesulfonate. The reaction takes place in dilute acetic acid in the presence of sodium acetate. Recently, 4-azo-benzenediazonium fluoroborate was proposed as the reagent, and dimethyl sulfoxide or dimethylformamide (18, 19) as the reaction medium in which intensely colored di-cations of bis-azo dyes can be formed. 

---