Dialkylamino

Likewise, the ynaminoketones with phenylhydrazine give a similar mixture of isomerie l-phenyl-3-dialkylammo-5-methylpyrazoles (369) and l-phenyl-5-dialkylamino-3-methylpyrazoles (370) in the same 3 4 ratio (87ZOR1635). 

Scheme 12 General synthesis of 5-dialkylamino-3-ethoxycyclopentadienes 60 from 3-di-alkylamino-l-ethoxypropenylidenechromium complexes 57 and alkynes in a donor solvent. Conditions A pyridine, 55-80 °C, 1.5-4 equiv. of the alkyne B MeCN, 80 °C, slow addition of 2-4 equiv. of the alkyne. For further details see Table 1 [43,44,60,61]...

Amino-hydroximino-methyl)-pyridin liefert mit Dimethylamino-trichlor-methan beim Sie-den in Acetonitril 5-Dialkylamino-3-(2-pyridyl)-l,2,4-oxadiazol (29% Schmp. 82—85°)113 ... 

Oxalsaure-l-chlorid-2-ethylester-l-hydroximid addiert sich an Dialkylcyanamide beim Erhit-zen auf 100 in 1,2-Dimethoxy-ethan und mit Triethylamin als Base zu 5-Dialkylamino-3-ethoxy-carbonyl-1,2,4-oxadiazolen350 z.B. ... 

Regioselective N-2 methylation of 5-phenoxy- and 5-dialkylamino- 3-amino-4-cyano-2//-1,2,6-thiadiazine 1,1-dioxides (99 R = OPh or NR 2) (Section 6.16.9.1.2) has been noted (Equation (3)) <91S753>. 

In the alkylation of 5-dialkylamino-3-imino-l,2,4-dithiazoles (98), the occasional use of acetonitrile as solvent resulted in its 1,3-dipolar addition to the heterocycle, yielding 1,2,4-thiadiazoles (99) as the minor products.93... 

The thermal decomposition of 5-dialkylamino-3-alkylimino-l,2,4-dithia-zoles (100) gives products derived from two molecules of the reactant, with loss of one atom of sulfur. They were formulated as substituted 3,5-bis(thio-ureido)-l,2,4-thiadiazolidines (101), and were thought to arise by a mechanism involving intermediate spirans.94 They were also obtained from the thioureido-l,2,4-dithiazoles (102) by successive alkylation and aminolysis.95 An X-ray analysis has confirmed the structure of 101 (R = Me) in its solid state.96... 

Thiadiazoles have been isolated as minor by-products in certain reactions of 5-(dialkylamino)-3-imino-l,2,4-dithiazoles in aceto- or benzo-nitrile as a result of 1,3-dipolar addition of the solvent. 

The p-substituted amino ketones can be reduced readily to the more stable P-dialkylamino alcohols, many of which are useful local anaesthetics. Thus the local anaesthetic Tutocaine is made from the Mannich base derived from formaldehyde, methyl ethyl ketone and dimethylamine, followed by reduction and conversion into the p-aminobenzoate ... 

This reactivity pattern underlies a group of important synthetic methods in which an a-substituent is displaced by a nucleophile by an elimination-addition mechanism. Even substituents which are normally poor leaving groups, such as alkoxy and dialkylamino, are readily displaced in the indole series. 

An important method for construction of functionalized 3-alkyl substituents involves introduction of a nucleophilic carbon synthon by displacement of an a-substituent. This corresponds to formation of a benzylic bond but the ability of the indole ring to act as an electron donor strongly influences the reaction pattern. Under many conditions displacement takes place by an elimination-addition sequence[l]. Substituents that are normally poor leaving groups, e.g. alkoxy or dialkylamino, exhibit a convenient level of reactivity. Conversely, the 3-(halomethyl)indoles are too reactive to be synthetically useful unless stabilized by a ring EW substituent. 3-(Dimethylaminomethyl)indoles (gramine derivatives) prepared by Mannich reactions or the derived quaternary salts are often the preferred starting material for the nucleophilic substitution reactions. 

Dimethyl acetylenedicarboxylate (DMAD) has also been used to catalyse gramine alkylations (see Entry 7). It may function by both activating the dialkylamino leaving group and deprotonating the nucleophile[3]. 

A traditional method for such reductions involves the use of a reducing metal such as zinc or tin in acidic solution. Examples are the procedures for preparing l,2,3,4-tetrahydrocarbazole[l] or ethyl 2,3-dihydroindole-2-carbox-ylate[2] (Entry 3, Table 15.1), Reduction can also be carried out with acid-stable hydride donors such as acetoxyborane[4] or NaBHjCN in TFA[5] or HOAc[6]. Borane is an effective reductant of the indole ring when it can complex with a dialkylamino substituent in such a way that it can be delivered intramolecularly[7]. Both NaBH -HOAc and NaBHjCN-HOAc can lead to N-ethylation as well as reduction[8]. This reaction can be prevented by the use of NaBHjCN with temperature control. At 20"C only reduction occurs, but if the temperature is raised to 50°C N-ethylation occurs[9]. Silanes cun also be used as hydride donors under acidic conditions[10]. Even indoles with EW substituents, such as ethyl indole-2-carboxylate, can be reduced[ll,l2]. 

A rigidized molecule obtained when the two a-carbons of the trimethine chain are linked by a dimethylene bridge cannot be planar. According to the resonance concept, its stability increases as a bathochromic effect of 41 nm is observed (122). The of the bistyryl dye obtained by the substitution of the -proton in the chain of a styryl dye by a dialkylamino group is nearly the same as for the parent styryl dye (123). 

The condensation of a-haloketones with monosubstituted alkyl or aryl-selenoureas (25) leads to 2-alkylamino- (26. 27) or 2-arylaminOselana-zoles (28) while disubstituted selenoureas give 2-(dialkylamino) selenazoles (26. 27) (Table X-3a). 

Isopropylidene and benzylidene hydrazones of selenazole unsubstituted in the 5-position react with p-nitrosodimethylanilines or p-nitrosodiethyl-anilines when heated in organic solvents in the presence of acetic acid or pyridine (49). Highly colored crystalline 2-hydrazono-5-(p-dialkylamino-phenylimino)selenazoles are recovered from the reaction medium (Table X-10). 

Hofmann (1) had already demonstrated this type of hydrolysis, which occurs often where the possibility of a tautomerism towards the imino form exists. In the case of 2-(dialkylamino) selenazolines. hydrolysis does not take place. 

Photocurable materials for photographic films contain pentaerythritol and dialkylamino and/or nitrile compounds, which have good adhesion and peelabihty of the layers, and produce clear transfer images (97,98). 

Polymerization ofiVIasked Disilenes. A novel approach, namely, the anionic polymerization of masked disilenes, has been used to synthesize a number of poly(dialkylsilanes) as well as the first dialkylamino substituted polysilanes (eq. 13) (111,112). The route is capable of providing monodisperse polymers with relatively high molecular weight M = lO" — 10 ), and holds promise of being a good method for the synthesis of alternating and block copolymers. 

The reaction of halosilanes with alcohols proceeds analogously. Dihinctional amines react with tetrahalosilanes to yield tetrakis(dialkylamino)silanes. 

Alkylamines react with leucoquinizarin in a stepwise manner to give l-alh anaino-4-hydroxyanthraquinone, and 1,4-diaLkylamino derivatives after air oxidation. Aromatic amines react similarly in the presence of boric acid as a catalyst. The complex formed (129) causes the less nucleophilic aromatic amines to attack at the 1-, and 4-positions. 

Other methods of generating a-aminoketones in situ are common, if somewhat less general than the methods already described. 2-Nitrovinylpyrrolidine, which is readily available, yields 2,3-bis(3-aminopropyl)pyrazine on reduction and this almost certainly involves ring opening of the intermediate enamine to an a-aminoketone which then dimerizes under the reaction conditions (Scheme 59) (78TL2217). Nitroethylene derivatives have also served as a-aminoketone precursors via ammonolysis of the derived epoxides at elevated temperatures (Scheme 60) (76S53). Condensation of 1,1-disubstituted hydrazine derivatives with a-nitro-/3-ethoxyethylene derivatives has been used in the synthesis of l,4-dialkylamino-l,4-dihydropyrazines (Scheme 61) (77S136). 

The other main reaction in this class is the Dieckmann-type cyclization of the intermediates (163) from 4(6)-halo-5-ethoxycarbonylpyrimidines with AC-substituted /3-alanine esters and nitriles, and related compounds, to give 5,6,7,8-tetrahydro-5-oxopyrido[2,3-[Pg.221]

The corresponding saturated dialkylamino ketones (Mannich bases) have also been used to provide 5,6-dihydro derivatives, which are oxidized in air to aromatic pyrido[2,3-[Pg.229]

Alkoxy-2,l-benzisoxazole-4,7-diones undergo ready nucleophilic displacement of the 3-alkoxy substituent, yielding 3-alkylamino and 3-dialkylamino derivatives with primary and secondary amines, respectively (67TL4313). In this instance the 4-carbonyl group apparently provides an activating effect. 

Azafulvene, 6-aryl-6- N, N-dimethylamino-dimerization, 4, 309 1-Azafulvene, 6,6-bis(alkylthio)-synthesis, 4, 310 1-Azafulvene, 6-dialkylamino-reactions... 

H-Azepine, bis(trifluoromethyl)dihydro-synthesis, 7, 539 3H-Azepine, 2-butoxy-synthesis, 7, 536 3H-Azepine, 2-butylamino-synthesis, 7, 536 3H-Azepine, 2-dialkylamino-quaternization, 7, 511 synthesis, 7, 536... 

Benzazepin-4-one, 2-dialkylamino-hydrolysis, 7, 510 Benzazepinones azatropolone character, 7, 503 synthesis, 7, 529 Benzazepinones, 2-ethoxy-azatropolone character, 7, 503 Benzazepinones, hydroreactivity, 7, 503 Benzazepin-2-ones alkylation, 7, 514 tautomerism, 7, 503... 

Benzo[6]thiophene, 4,7-dialkoxy-synthesis, 4, 930 Benzo[6]thiophene, 2,3-dialkyl-synthesis, 4, 877-878 Benzo[6]thiophene, 3 -(dialkylamino)-synthesis, 4, 925 Benzo[c]thiophene, 1,3-diaryl-oxidative ring opening, 4, 768 Benzo[6]thiophene, 2,3-dibromo-reactions, 4, 830... 

Coumarin, 7-(dialkylamino)-, I, 333 Coumarin, 7-dialkylamino-4-hydroxy-synthesis, 3, 808... 

Furoxans, bis[(acetoxyalkyl)carbonyl]-synthesis, 6, 421 Furoxans, bisarylsulfonyl-synthesis, 6, 423 Furoxans, bis(dialkylamino)-synthesis, 6, 414 Furoxans, butylhexynyl-synthesis, 6, 423 Furoxans, decamethylenering cleavage, 6, 405 Furoxans, diacyl-thermolysis, 6, 81 synthesis, 6, 442 Furoxans, diadamant-1-yl-ring cleavage, 6, 404 Furoxans, dialkoxycarbonyl-synthesis, 6, 423 Furoxans, dialkyl-synthesis, 6, 423 Furoxans, diaryl-ozonolysis, 6, 405 Furoxans, diaroyl-isoxazoles from, 6, 82 Furoxans, dibenzoyl-synthesis, 6, 423 Furoxans, diethoxycarbonyl-synthesis, 6, 423... 

Oxazole, 2-aryl-4-chloro-5-phenyl-synthesis, 6, 219 Oxazole, 2-dialkylamino-synthesis, 6, 218 Oxazole, 5-dialkylamino-synthesis, 6, 217, 219 Oxazole, 5-dialkylamino-2-phenyl-reactions... 

Pyran, 2,2-dialkoxy-3,4-dihydro-synthesis, 3, 772 Pyran, 2-dialkylamino-3-(2-... 

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