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2- Aminopyridines, synthesis

Aminopyridines. Aminopyridines are key intermediates for the synthesis of important pharmaceutical and agricultural products (88,89). [Pg.336]

An important early method simulated the well-known Widman-Stoermer cinnoline synthesis. 3-Aminopyridine-2- or -4-alkenes such as (348) gave pyrido-[3,2-c]- or -[3,4-c]-pyridazines on diazotization and alkaline cyclization (66JCS(C)2053>. [Pg.243]

The historieal aspeets of synthesis, study and applieation of heteroeyelie azoeompounds (HAC) pyridynie of a line in airalytieal ehemistry are eonsidered. Works of A.E. Chieibabin on diazotation of 2-aminopyridine and it azoeopulation with resoreinol (PAR) and 2-naphthol (PAN-2). [Pg.399]

Syntheses of Nicotine. Pictet and Cr pieux found that 3-aminopyridine mueate on dry distillation yielded l-(3-pyridyl)pyrrole (I), and this, in accordance with the usual behaviour of such pyrrole derivatives, transfers its pyridyl substituent from the 1- to the 2-position at a red heat giving 2-(3-pyridyl)pyrrole (II), which is nomieotyrine. The potassium derivative of this reacts with methyl iodide to form l-methjd-2-(3-pyridyl)-pyrrole methiodide, which is identical with nieotyrine methiodide (III), and on distillation with lime yields nieotyrine (IV Cl — CH). For a re-investigation of this synthesis see Spath and Kainrath. ... [Pg.40]

A variety of aryl systems have been explored as substrates in the Knorr quinoline synthesis. Most notable examples are included in the work of Knorr himself who has demonstrated the high compatibility of substituted anilines as nucleophilic participants in that reaction. In the case of heteroaromatic substrates however, the ease of cyclization is dependent on the nature and relative position of the substituents on the aromatic ring." For example, 3-aminopyridines do not participate in ring closure after forming the anilide... [Pg.439]

The labeled aminopyridine 103 was further used for the synthesis of iV-(2-ethyl-3-chloro-4-pyiidin-2-yl-[ C]-4-(4-chlorophenoxy)phenylacetamide-[ C]-1)(98MI1). [Pg.184]

Reaction of 2-aminopyridines with formaldehyde and electron rich styrenes 383 permitted the synthesis of 3,4-dihydro-2//-pyrido[l,2-n]pyr-imidines 384 (96TL2615). First imines 382 formed they are involved in a formal aza-Diels-Alder reaction to give compounds 384. [Pg.249]

Replacement of a benzene ring by its isostere, thiophene, is one of the more venerable practices in medicinal chemistry. Application of this stratagem to the NSAID piroxicam, gives tenoxicam, 136, a drug with substantially the same activity, nie synthesis of this compound starts by a multi-step conversion of hydroxy thiophene carboxylic ester 130, to the sulfonyl chloride 133. Reaction of that with N-methylglycinc ethyl ester, gives the sulfonamide 134. Base-catalyzed Claisen type condensation serves to cyclize that intermediate to the p-keto ester 135 (shown as the enol tautomer). The final product tenoxicam (136) is obtained by heating the ester with 2-aminopyridine [22]. [Pg.173]

In a similar way, 1,3-dinitrogen systems such as diamines, amidines, guanidines, aminothiazoles, aminopyridines, ureas and thioureas react with alkynyl-carbene complexes generating the corresponding heterocycles. Of particular interest is the reaction with ureas, as the process can be applied to the easy synthesis of pyrimidine derivatives [88] (Scheme 41). [Pg.89]

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 tremendous scope of utilization of DMAP and PPY as catalysts has led to an active interest in the development of their polymeric analogs. The pioneering work was carried out by Hierl et al (8) and Delaney et al. (9). They attached 4-dialkyl-aminopyridine derivatives to poly(ethyleneimine) and found the modified polymers to be highly active catalysts for hydrolysis of p-nitrophenylcarboxylates. Since then, many research groups have reported the synthesis of polymers functionalized with 4-dialkyl-aminopyridine (10-18). [Pg.73]

We have previously (13) reported a rapid two step synthesis of 4-(pyrrolidino)pyridine copolymers via the reaction of commercially available maleic anhydride copolymers with 4-aminopyridine followed by reduction with LiAlH, yielding polymers with a high degree of functionalization. [Pg.76]

As already described for the all-carbon-Diels-Alder reaction, a hetero-Diels-Alder reaction can also be followed by a retro-hetero-Diels-Alder reaction. This type of process, which has long been known, is especially useful for the synthesis of heterocyclic compounds. Sanchez and coworkers described the synthesis of 2-aminopyridines [48] and 2-glycosylaminopyridines 4-144 [49] by a hetero-Diels-Alder reaction of pyrimidines as 4-143 with dimethyl acetylenedicarboxylate followed by extrusion of methyl isocyanate to give the desired compounds (Scheme 4.30). This approach represents a new method for the synthesis of 2-aminopyridine nucleoside analogues. In addition to the pyridines 4-144, small amounts of pyrimidine derivatives are formed by a Michael-type addition. [Pg.300]

This approach involves intermolecular cyclization of two six-membered heterocycles substituted with appropriate functional groups. Synthesis of 83 by the reaction between 2-aminopyridines and 3-ethoxycarbonyM-pipcridonc hydrochloride 82 in polyphosphoric acid is provided as an example (Equation 5) <1996T7789>. [Pg.1017]

Syntheses of naphthyridone derivatives follow the same procedures as those of quinolones, except that substituted 2-aminopyridines (Gould-Jacobs modification) or substituted nicotinic ester/nicotinoyl chloride are used instead of anilines or o-halobenzoic acid derivatives. Most of the recently introduced quinolone antibacterials possess bicyclic or chiral amino moieties at the C-7 position, which result in the formation of enantiomeric mixtures. In general, one of the enantiomers is the active isomer, therefore the stereospecific synthesis and enantiomeric purity of these amino moieties before proceeding to the final step of nucleophilic substitution at the C-7 position of quinolone is of prime importance. The enantiomeric purity of other quinolones such as ofloxacin (a racemic mixture) plays a major role in the improvement of the antibacterial efficacy and pharmacokinetics of these enan-... [Pg.172]

The 5-, 6-, and 7-azaindoles were synthesized via the Pd-catalyzed heteroannulation of internal alkynes using orf/w-aminopyridine derivatives in an extention of Larock s indole synthesis [169], LiCl was found to be an essential component in order to obtain regioselectivity, reproducibility and improved yields. [Pg.226]

Irnidazo[ 1,2-tf ]py ridines were covered in CHEC(1984) <1984CHEC(6)613> along with others imidazoles fused to six-membered rings and they were reviewed together with imidazo[l,5- ]pyridines in CHEC-II(1996) <1996CHEC-II(8)249>. The chemical literature on this heterocycle is very abundant, due to its easy synthesis (most of the preparations use readily available 2-aminopyridines) and to the very broad spectrum of bioactivities displayed by many derivatives. A simple Beilstein search on the fully conjugated heterocycle (free sites everywhere) disclosed ca. 3000 hits for the past decade. Therefore, this chapter cannot be exhaustive in view of space limitations, but will mainly focus on the original synthetic methods that have appeared in the last decade. [Pg.457]

A lot of methods are available for the synthesis of this heterocycle, and most of them rely on the formation of the five-membered ring. In this section, only the methodologies of reasonable scope will be reported. The most classical method involves the cyclocondensation of 2-aminopyridine with an a-halo carbonyl compound. Due to the broad availability of the required substrates and the efficiency of this cyclocondensation, it continues to be the method of choice to prepare this heterocycle. New examples highlighting the generality of this reaction are collected in Table 14. [Pg.463]

Table 14 Synthesis of imidazo[1,2-a]pyridines through cyclocondensation of 2-aminopyridine and a-halo carbonyls 2-Aminopyridine a-Halo carbonyl Conditions Product Yield (%) Reference... Table 14 Synthesis of imidazo[1,2-a]pyridines through cyclocondensation of 2-aminopyridine and a-halo carbonyls 2-Aminopyridine a-Halo carbonyl Conditions Product Yield (%) Reference...
Studies on the synthesis of [l,2,4,3]triazaphospholo[l,5-tf]pyridines have been reported by Schmidpeter et al. <1993JPR458, 1994PS381, 1995ZNB558>. The reaction pathway starts from 2-aminopyridine 147 which is first subjected to an Anamination reaction to give 1,2-diaminopyridinium iodide 148, and this compound is treated with tris-dimethylaminophosphine to yield the five-membered phosphorus-containing heterocycle 149. [Pg.665]


See other pages where 2- Aminopyridines, synthesis is mentioned: [Pg.335]    [Pg.336]    [Pg.337]    [Pg.208]    [Pg.685]    [Pg.685]    [Pg.731]    [Pg.731]    [Pg.865]    [Pg.877]    [Pg.877]    [Pg.173]    [Pg.181]    [Pg.254]    [Pg.90]    [Pg.435]    [Pg.122]    [Pg.301]    [Pg.17]    [Pg.193]    [Pg.510]    [Pg.225]    [Pg.102]    [Pg.33]    [Pg.218]    [Pg.464]    [Pg.619]    [Pg.622]   
See also in sourсe #XX -- [ Pg.20 ]




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2-Aminopyridine

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