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2- Aminopyridine irradiation

Reaction of 2 equiv of 2-aminopyridines with 2-hydropolyfluoroalk-2-anoates 351 in MeCN in the presence of NEts at 90 °C for 50 h afforded a mixture of the isomeric 2-oxo-2H- and 4-oxo-4//-pyrido[l,2-n]pyrimidines 110 and 111. Reaction of 3 equiv of 2-amino-pyridines and 2-hydropoly-fluoroalk-2-enoates 351 in MeCN in the presence K2CO3 could be accelerated by ultrasonic irradiation (125W). 2-Amino-6-methylpyridine yielded only 2-substituted 6-methyl-4//-pyrido[l,2-n]pyrimidin-4-ones 111 (R = 6-Me), whereas 2-amino-5-bromopyridine gave a mixture of 7-bromo-4//-pyrido[l,2-n]pyrimidin-4-one (111, R = 7-Br, R = CF2C1) and 2-(chlor-o,difluoromethyl)-6-bromoimidazo[l, 2-n]pyrimidine-3-carboxylate in 44 and 8% yields, respectively (97JCS(P 1)981). Reactions in the presence of K2CO3 in MeCN at 90°C for 60h afforded only imidazo[l,2-n]pyrimidine-3-carboxylates. [Pg.243]

A one-pot synthesis of thiohydantoins has been developed using microwave heating [72]. A small subset of p-substituted benzaldehydes, prepared in situ from p-bromobenzaldehyde by microwave-assisted Suzuki or Negishi reactions, was reacted in one pot by reductive amination followed by cyclization with a thioisocyanate catalyzed by polystyrene-bound dimethyl-aminopyridine (PS-DMAP) or triethylamine, all carried out under microwave irradiation, to give the thiohydantoin products in up to 68% isolated yield (Scheme 16). [Pg.44]

The photocyclization of enamides has been widely employed in the construction of heterocyclic systems the N-acryloyl-2-aminopyridines 37, for example, are converted on irradiation to the lactams 38.36 Numerous benzylisoquinoline alkaloids have been prepared using this approach, and in particular, the syntheses of benzo[c]phenanthridine alkaloids have been reviewed.37 Thus, irradiation of the [Z]-l-ethylidene-2-benzoyltetra-hydroisoquinoline 39 affords the corresponding 8-oxoberberine 4038 competing photoisomerization to the E-isomer is observed but cyclization occurs only via the Z-isomer. Examples of syntheses of Amaryllidaceae and indole alkaloids have also been reported. In this way, the precursor 41 of ( )-lycoran has been obtained by oxidative cyclization of the enamide 42.39... [Pg.246]

For this purpose, perfluorooctanesulfonyl-tagged benzaldehydes were reacted with 1.1 equivalents of a 2-aminopyridine (or 2-aminopyrazine), 1.2 equivalents of an isonitrile, and a catalytic amount of scandium(III) triflate [Sc(OTf)3] under micro-wave irradiation in a mixture of dichloromethane and methanol (Scheme 7.85). A ramp time of 2 min was employed to achieve the pre-set temperature, and then the reaction mixture was maintained at the final temperature for a further 10 min. The fluorous tag constitutes a multifunctional tool in this reaction, protecting the phenol in the condensation step, being the phase tag for purification, and serving as an acti-... [Pg.353]

Pyridone on irradiation in concentrated solution gives the dimer (437) 2-aminopyridine behaves similarly. The acridizinium ion (see Scheme 39) like anthracene undergoes [4 + 4] photocycloaddition... [Pg.235]

Pyridone (260), unlike quinolin-2-one and coumarin, does not yield a dimer of the cyclobutane type, but on irradiation in concentrated solution is converted into the dimer (261) by a novel 1,4-cycloaddition process.266,267 The same dimerization has been observed in a number of nuclear-substituted pyridones.286,268 An analogous process is reported to occur in various 2-aminopyridines [Eq. (66)], on irradiation in acid solution.267... [Pg.68]

Keywords aldehyde, isocyanide, 2-aminopyridine, montmorillonite K-10, micro-wave irradiation, imidazol[l,2-a]annulated pyridine... [Pg.268]

A mixture of benzaldehyde la (106 mg, 1 mmol) and 2-aminopyridine 3a (94 mg, 1 mmol) was irradiated in an unmodified household microwave oven for 1 min (at full power of 900 W) in the presence of montmorillonite K-10 clay (50 mg). After addition of benzyl isocyanide 2a (117 mg, 1 mmol), the reaction mixture was further irradiated successively (2 min) at 50% power level for a duration of 1 min followed by a cooling period of 1 min. The resulting product was dissolved in dichlorometliane (2x5 mL) and the clay was filtered off. The solvent was removed under reduced pressure and the crude product was purified either by crystallization or by passing it through a small bed of silica gel using EtOAc-hexane (1 4, v/v) as eluent to afford 4a. [Pg.269]

Lateral-nuclear migrations also occur with heteroarenes, and it is reported that all three isomeric nitraminopyridines (300) irradiated at 254 nm in methanol solution undergo this type of rearrangement. Thus the 2-isomer yields both 3-nitro- and 5-nitro-2-aminopyridines in a respective ratio of 6.25 1, 3-nitraminopyridine gives the 4-nitro- and 2-nitro-3-aminopyridines (1.28 1 ratio respectively), while the 4-nitramine isomer produces only 3-nitro-4-aminopyridine. Under similar conditions, l-methyl-4-nitraminopyridine... [Pg.367]

MW irradiation activated the reaction of dimedone with aniline or p-chloroaniline in formic acid to give the acridines 356, which can be derivatized as the respective Ws-oxime and Ws-phenylhydrazone. However, under the same reaction condition 2-aminopyridine gave the corresponding xanthene derivative (06ARK178). [Pg.63]

The reactants are exposed to MW irradiation to afford the corresponding imida-zo[l,2-a]pyridines, imidazo[l,2-a]pyrazines and imidazo[l,2-a]pyrimidines (Scheme 2.2-48). The process is general for all three components, i.e. aldehydes (aliphatic, aromatic, and vinylic), isocyanides (aliphatic, aromatic, and cyclic) and amines (2-aminopyridine, 2-aminopyrazine, and 2-aminopyrimidine). [Pg.80]

More recently, Vittal and co-workers have used a similar approaeh in the structural study and solid-state reactivity of a series of moleeular salts based on trans-4,4 -stilbenedicarbo ylic acid (H2SDC) with various amines (cyclohe>ylamine, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, cystamine, guanidine, 4-aminopyridine, piperizine), resulting the salt obtained from the combination with 1,3-diaminopropane photoreactive in the solid state, allowing the quantitative dimerisation upon UV irradiation. ... [Pg.294]

Sulfuric acid (s. a. under Irradiation) Chlorination of aminopyridines... [Pg.460]

Photolysis of aminopyridines has been studied by Taylor and his co-workers. Ultraviolet irradiation of 2-aminopyridine (and several substituted 2-aminopyridines) in hydrochloric acid solution results in the formation of the 1,4-dimer having the anti-trans configuration IX-SS. [Pg.63]

A solvent-free reaction of enaminonitriles with amines provides 4-substituted-3-cyano-2-aminopyridines (Scheme 5). The reaction proceeds well under both conventional heating and MW irradiation although MW requires far less time (minutes) (13T1138). [Pg.355]


See other pages where 2- Aminopyridine irradiation is mentioned: [Pg.39]    [Pg.190]    [Pg.193]    [Pg.64]    [Pg.24]    [Pg.311]    [Pg.272]    [Pg.132]    [Pg.348]    [Pg.202]    [Pg.287]    [Pg.39]    [Pg.232]    [Pg.93]    [Pg.185]    [Pg.122]    [Pg.1041]    [Pg.766]    [Pg.803]    [Pg.380]    [Pg.251]    [Pg.12]    [Pg.279]    [Pg.242]    [Pg.39]    [Pg.237]   
See also in sourсe #XX -- [ Pg.313 ]




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2-Aminopyridine

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