Dialkyl amides

Phenylacetonitrile (pATDMSO = 21.9) is considerably more acidic than acetonitrile. Deprotonation can be done with sodium amide. Dialkylation has been used in the synthesis of meperidine, an analgesic substance.62... 

Peracids can also be prepared from reaction of hydrogen peroxide with acyl halides, anhydrides, amides, dialkyl phosphates, N-acylimidazoles, aromatic aldehydes, lipase catalysis and esters (Figure 2.38).100-107... 

R C(OR )=NR , or their salts R C(OR )=NR X , respectively, has remained the method of choice for the synthesis of thionocarboxylates. > > <14-421 The starting materials can be obtained by addition of alcohols to nitriles, by alcoholysis of imido-chlorides, or by O-alkylation of amides. Dialkyl mono-(170) and bis-thiono-oxalates (171) are prepared in this way, in which case it is especially advantageous to use the imidates as free bases instead of their... 

FS(0)20CH3. Colourless liquid, b.p. 94°C. Functions as a powerful methylating agent, even for amides and nitriles which are not attacked by conventional alkylating agents like dialkyl sulphates. 

Additives acting on the pour point also modify the crystal size and, in addition, decrease the cohesive forces between crystals, allowing flow at lower temperatures. These additives are also copolymers containing vinyl esters, alkyl acrylates, or alkyl fumarates. In addition, formulations containing surfactants, such as the amides or fatty acid salts and long-chain dialkyl-amines, have an effect both on the cold filter plugging point and the pour point. 

We name compounds of the type RCNHR and RCNR2 as N alkyl and N N dialkyl substituted derivatives of a parent amide... 

The imide proton N-3—H is more acidic than N-1—H and hence this position is more reactive toward electrophiles in a basic medium. Thus hydantoins can be selectively monoalkylated at N-3 by treatment with alkyl haUdes in the presence of alkoxides (2,4). The mono-A/-substituted derivatives (5) can be alkylated at N-1 under harsher conditions, involving the use of sodium hydride in dimethylform amide (35) to yield derivatives (6). Preparation of N-1 monoalkylated derivatives requires previous protection of the imide nitrogen as an aminomethyl derivative (36). Hydantoins with an increased acidity at N-1—H, such as 5-arylmethylene derivatives, can be easily monoalkylated at N-3, but dialkylation is also possible under mild conditions. 

A number of synthetic polymers having the abHity to control filtration rates at high temperature and in the presence of calcium and magnesium have also been developed (88). Such materials include vinyl sulfonate—vinyl amide copolymers (89,90), a copolymer of AMPS and A/,A/-dialkyl (meth) acrylamide (91) and a sulfonated hydroxylated polymer (92). AppHcation levels for these materials range from 5 to 18 kg/m (2—6 lb /bbl). Sulfonated asphalt is also used for high temperature filtration control. 

Dialkyl and diarylthaHium(III) derivatives are stable, crystalline soHds that melt at 180—300°C. The dimethylthaHium derivatives of CN , CIO, BF, and NO 2 contain linear (CH2)2T1 cations and the free anions (19). In aqueous solutions, they ionize to the (CH2)2T1(H20) ions, except those derivatives containing alkoxide, mercaptide, or amide anions, which yield dimeric stmctures (20,21). 

A number of compounds of the types RBiY2 or R2BiY, where Y is an anionic group other than halogen, have been prepared by the reaction of a dihalo- or halobismuthine with a lithium, sodium, potassium, ammonium, silver, or lead alkoxide (120,121), amide (122,123), a2ide (124,125), carboxylate (121,126), cyanide (125,127), dithiocarbamate (128,129), mercaptide (130,131), nitrate (108), phenoxide (120), selenocyanate (125), silanolate (132), thiocyanate (125,127), or xanthate (133). Dialkyl- and diaryUialobismuthines can also be readily converted to secondary bismuthides by treatment with an alkali metal (50,105,134) ... 

No systematic study of the mass spectra of pyridopyrazines has been noted, but those of 2,3-dialkyl and 2,3-diaryl derivatives have been recorded 750MS97), and mass spectrometry has been used in the elucidation of problems in the reactions of pyrido[2,3-f ]pyrazines with amide ion (including use of and derivatives) (79JHC305), and of pyrido[2,3-f ]pyrazinium salts with indoles (78ZOR431). The mass spectra of some 1-deazaflavins have been recorded (74JCS(P1)1965). 

When hexafluoroacetone reacts with amides, urethanes [25], thioamides [26], amidines [27], sulfonamides [28, 29], sulfinainides [20], and f),0-dialkyl-amido-phosphates [27], the correspondmg semiamidals are formed m nearly quantitative yield The thermal stabihty of these adducts toward the retro reaction increases with the nucleophihcity of the ammo compound [5] Many polyfluonnated carbonyl compounds react likewise [22 22] On treatment of ureas [34], thioureas [34], thioamides [26], and C,77 diarylatmdmes [27, 25] first with hexa- fluoroacetone and then with dehydratmg agents, heterodienes are obtamed (equation 4)... 

Acylation of norephedrine (56) with the acid chloride from benzoylglycolic acid leads to the amide (57), Reduction with lithium aluminum hydride serves both to reduce the amide to the amine and to remove the protecting group by reduction (58), Cyclization by means of sulfuric acid (probably via the benzylic carbonium ion) affords phenmetrazine (59), In a related process, alkylation of ephedrine itself (60) with ethylene oxide gives the diol, 61, (The secondary nature of the amine in 60 eliminates the complication of dialkylation and thus the need to go through the amide.) Cyclization as above affords phendimetra-zine (62), - Both these agents show activity related to the parent acyclic molecule that is, the agents are CNS stimulants... 

These constitutions have recently received support from the work of A. Haller. If they are correct, then thujone should be capable of yielding trialkyl substitution products, whilst isothujone should not be able to go beyond the dialkyl stage. By alkylation with the assistance of sodium amide, triallylthujone could be prepared, but no higher substitution product than dimethylisothujone could be prepared from isothujone. In the course of his work, Haller prepared the following alkyl derivatives of the two ketones —... 

Ketones, esters, and nitriles can all be alkylated using LDA or related dialkyl-amide bases in THE. Aldehydes, however, rarely give high yields of pure products because their enolate ions undergo carbonyl condensation reactions instead of alkylation. (We ll study this condensation reaction in the next chapter.) Some specific examples of alkylation reactions are shown. 

The carbanion 5, formed from V,V-diethyl-5-phenyl-3//-azepin-2-amine (4) with potassium amide in liquid ammonia, or with lithium 2,2,6,6-tetramethylpiperidide in tetrahydrofuran, is thiolated by dialkyl or diaryl disulfides to yield 3-(alkylsulfanyl)-3//-azepines, e.g. 6.38... 

N,N-Dialkyl-amide konnen z. B. mit Lithium-triathyl-hydrido-boranat in THF zu den... 

A recent development in understanding the reactivity of bases has focused on their structures in solution and in the crystalline state. Due to the importance of dialkyl amide bases, there is a significant body of work, led by Williard and Collum , that has attempted to understand the structures of these reactive molecules. It is clear that they are aggregates. Lithium diisopropylamide (LiN/-Pr2) was isolated from a THF solution and X-ray crystallography revealed a dimeric structure (13 R = i-Pr, S = THF) in the... 

The reaction with disubstituted formamides and phosphorus oxychloride, called the Vilsmeier or the Vilsmeier-Haack reaction,is the most common method for the formylation of aromatic rings. However, it is applicable only to active substrates, such as amines and phenols. An intramolecular version is also known.Aromatic hydrocarbons and heterocycles can also be formylated, but only if they are much more active than benzene (e.g., azulenes, ferrocenes). Though A-phenyl-A-methyl-formamide is a common reagent, other arylalkyl amides and dialkyl amides are also used. Phosgene (COCI2) has been used in place of POCI3. The reaction has also been carried out with other amides to give ketones (actually an example of 11-14),... 

In an indirect amination process, acyl halides are converted to amino acids. Reaction of the acyl halide with a chiral oxazolidinone leads to a chiral amide, which reacts with the N=N unit of a dialkyl azodicarboxylate [R"02C—N=N—CO2R ]. Hydrolysis and catalytic hydrogenation leads to an amino acid with good enantioselectivity. ... 

When secondary amines are treated with nitrous acid, N-nitroso compounds (also called nitrosamines) are formed. The reaction can be accomplished with dialkyl-, diaryl-, or alkylarylamines, and even with mono-N-substituted amides RCONHR -I-HONO RCON(NO)R. Tertiary amines have also been N-nitrosated, but in these cases one group cleaves, so that the product is the nitroso derivative of a secondary amine.The group that cleaves appears as an aldehyde or... 

The groups R2N and Cl can be added directly to alkenes, allenes, conjugated dienes, and alkynes, by treatment with dialkyl-V-chloroamines and acids. " These are free-radical additions, with initial attack by the R2NH- radical ion. " N-Halo amides (RCONHX) add RCONH and X to double bonds under the influence of UV light or chromous chloride. " Amines add to allenes in the presence of a palladium catalyst. ... 

Finally, the N-propargyl-P,P-dialkyl or diaryl phosphinous amides rearrange at room temperature to the P-(4-azabutadienyl)phosphanes 28 [127] (Scheme 29). Interestingly, this rearrangement did not occur in other structurally similar P-N functionalities (R=OEt, OTr, NEt2). 

The stable P-unsubstituted phosphinous amide H2PN(SiMe3)2 has been shown to suffer the nucleophilic displacement of the disilazane moiety by the action of thiols R-SH giving the phosphinous thioesters R-S-PH2 [13]. For the sake of brevity we shall not comment on other relevant reactions of AT-silyl phosphinous amides, such as the anionic P-silylation [115] and P-alkylation [22], the consecutive dialkylation of PH derivatives [18] and the fluorodesily-lation of P-fluoro-JV-silyl derivatives [140]. 

Note also that dialkyl ketones such as acetone and 3-pentanone are slightly more acidic than the simple alcohols in DMSO. Use of alkoxide bases in DMSO favors enolate formation. For the amide bases, -K b-h) << a(c-H)> and complete formation of the enolate occurs. 

---