Dimethylformamide, reaction with

Dimethylformamide, reaction with dimethyl sulfate, 47, 52 reaction with phosphorus oxychloride and cyclohexanone, 16,18 Dimethylformamide-dimethyl sulfate complex, preparation of, 47,... 

Trifluoromethanesulfonic acid is miscible in all proportions with water and is soluble in many polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and acetonitrile. In addition, it is soluble in alcohols, ketones, ethers, and esters, but these generally are not suitably inert solvents. The acid reacts with ethyl ether to give a colorless, Hquid oxonium complex, which on further heating gives the ethyl ester and ethylene. Reaction with ethanol gives the ester, but in addition dehydration and ether formation occurs. 

Furalazine, Acetylfuratrizine, Panfuran-S. Heating nitrovin in butanol or dimethylformamide at 100—130°C affords furalazine, 6-[2-(5-nitro-2-furanyl)ethenyl]-l,2,4-triazine-3-amine (34). An improved synthesis originates with 5-nitro-2-furancarboxaldehyde and acetone, proceeds through 4-(5-nitro-2-furanyl)-3-buten-2-one followed by a selenium dioxide oxidation to the pymvaldehyde hydrate, and subsequent reaction with aininoguariidine (35). Furalazine, acetylfuratrizine (36), and the A[-A/-bis(hydroxymethyl) derivative, Panfuran-S, formed from the parent compound and formaldehyde (37), are systemic antibacterial agents. 

However, 17a,21-acetonides (103), as well as acetals of other ketones or aldehydes, can be easily prepared by acid-catalyzed exchange reaction with dimethoxypropane or other alkyl acetals in dimethylformamide or benzene. Enol etherification of the A -S-ketone also occurs with the former procedure. 

In similar fashion, A-substituted-2(3fT)-oxazolones were prepared directly from the hydroxy-ketone by reaction with urethanes in the presence of pyridine and dimethylformamide or by using isocyanates. 

In an initial step the reactive formylating agent is formed from N,N-dimethylformamide (DMF) 2 and phosphorus oxychloride. Other N,N-disubstituted formamides have also found application for example A -methyl-A -phenylformamide is often used. The formylating agent is likely to be a chloromethyl iminium salt 4—also called the Vilsmeier complex (however its actual structure is not rigorously known)—that acts as the electrophile in an electrophilic substitution reaction with the aromatic substrate 1 (see also Friedel-Crafts acylation reaction) ... 

Cyclohexanone, 46, 18, 27, 36, 82 reaction with dimethylformamide and phosphorus oxychloride, 46, 18... 

Cydopentadienylsodium, reaction with dimethylformamide-dimethyl sulfate complex, 47, S3 1,3-Cyclopentanedione, 2-methyl-, 47, 83... 

Tin phthalocyanines can be prepared using tin(II)110 or -(IV)154 chlorides. The reaction can be performed in 1-chloro-1 10,1 37,1 55 or 1-bromonaphthalene,154 starting from phthalonitrile110137154,155 or phthalic anhydride. In the second case, urea and ammonium molyb-date(VI) arc added.137 The central tin atom can also be introduced into metal-free phthalocyanine by the reaction with tin(IV) chloride in dimethylformamide.141 Treatment of PcSnCl2 with disodium phthalocyanine in refluxing 1-chloronaphthalenc forms a sandwich-like bis-(phthalocyanine) Pc2Sn.154... 

Vanadium phthalocyanine (PcVO) is prepared from vanadium(IIl) chloride in a melt of phthalonitrile228 to which sometimes ammonium vanadate137 or molybdate229 and urea are added. Also a reaction with vanadium(V) oxide and phthalonitrile in pen tan-1-ol has been performed.230 Besides these direct syntheses, transformation of PcH2 to PcVO in refluxing dimethylformamide with vanadyl sulfate (V0S04) has been carried out.231... 

Trimethylsilyl halides can also be used for analogous reactions with arenediazo-nium tetrafluoroborates, as shown by Keumi et al. (1989). These authors treated 2-fluorenediazonium tetrafluoroborate in A/,Af-dimethylformamide or -acetamide with trimethylsilylchloride, -bromide, or -iodide in the presence of an excess of N-chlorosuccinimide, Af-bromosuccinimide, or methyl iodide, respectively, at 60 °C (Cl, Br) or at room temperature (I). The yields of the 2-halofluorenes were good in addition fluorene, the product of hydro-de-diazoniation, was obtained, if the reaction was run in tetrahydrofuran/Af,7V-dimethylformamide mixtures. The mechanism of these reactions, as well as that of the corresponding azido-de-diazoniation, is uncertain (see also Secs. 10.2 and 10.7). 

Non-Kolbe electrolysis of alicyclic p-hydroxy carboxylic acids offers interesting applications for the one-carbon ring extension of cyclic ketones (Eq. 35) [242c]. The starting compounds are easily available by Reformatsky reaction with cyclic ketones. Some examples are summarized in Table 13. Dimethylformamide as solvent and graphite as anode material appear to be optimal for this reaction. 

Experiments have been carried out to mimic the reactions of model systems for coenzyme F430 that is involved in the terminal step in the biosynthesis of methane, and that is able to dechlorinate CCI4 successively to CHCI3 and CH2CI2 (Krone et al. 1989). Nickel(I) isobacteriochlorin anion was generated electrolytically and used to examine the reactions with alkyl halides in dimethylformamide (Helvenston and Castro 1992). The three classes of reaction were the same as those observed with Fe(II) deuteroporphyrin IX that have already been noted. 

Amides often give rise to accidents that are difficult to interpret because so many reagents are present and/or because of the complexity of the reactions that are brought into play. It is difficult to find a classification for this group. The first point is the fact that most accidents are due to dimethylformamide (DMF), which is much used as a polar aprotic solvent. When attempting to classify these types of dangerous reactions with this compound, as a model, it can be said that they are mainly due to ... 

A New Improved Synthesis of Tricycle Thienobenzazepines Apphcation of chemistry recently developed by Knochel" combined with the well-described halogen dance (HD) reaction, allowed preparation of our key intermediate A in only three synthetic transformations (Scheme 6.4). In this respect, treatment of 2-bromo-5-methylthiophene with hthium diisopropylamide followed by dimethylformamide afforded aldehyde 11 in good yield, lodo-magnesium exchange with conunercial 4-iodo-3-nitro anisole followed by reaction with 11 afforded the thiophene catbinol 12. Dehydroxylation of 12 provided our key intermediate A which presented the requisite functionality to examine our approach to the construction of the seven-member ring system. 

An alternative method for reductive dediazonation involves in situ diazotization by an alkyl nitrite in dimethylformamide.96 This reduction is a chain reaction with the solvent acting as the hydrogen atom donor. 

The enamine 141 can be cyclized to the [l,2,4]triazolopyridopyrimidine 142 upon treatment with sodium ethoxide (Scheme 40) <2002M1297>. This fused tricyclic system may also be obtained, like the pteridine analogue (cf. Scheme 38), from the reaction of hydrazonoyl halides and pyridopyrimidines such as 143, and also by treatment of the triazolopyrimidine 144 with dimethylformamide dimethylacetal (DMF-DMA) dimethylacetal and subsequent ring closure <2003MOL333, 2003HAC491> (Scheme 41). Another series of triazolopyridopyrimidines, for example, 146, can be prepared from a hydrazine-substituted pyridopyrimidine 145, in two ways either directly by reaction with an acid chloride, or via a derived hydrazone (Scheme 42) <1996MI585>. 

As these acetals could be converted into the 4,6-O-ethylidene derivatives on treatment with acid, it was reasoned that use of a cyclic vinyl ether, namely, 3,4-dihydro-2H-pyran, might prevent this second process, thus leading to a more useful method of selective acetalation.338 An equimolar reaction with methyl a-D-glu-copyranoside for 4 days in N,N-dimethylformamide led to utilization of 88% of the glycoside, and the 6-(tetrahydropyran-2-yl) ether constituted —85% of the crude reaction-product. In contrast to the steric control apparent in this instance, reaction of 3,4-dihydro-2H-pyran with the axial and equatorial hydroxyl groups in dl-1,4,5,6-tetra-O-acetyl-mi/o-inositol was completely unselective,339 a fact that has been rationalized310 in terms of the probable mechanism of these reactions. 

The selective activation of the primary hydroxyl group in methyl a-D-glucopyranoside by reaction with carbon tetrachloride and tris(dimethylamino)phosphine in A/.N-dimethylformamide at —40° has been reported.381 An alkoxytris(dimethylamino)phosphonium... 

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