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Pyridyls

Yang W H, Hulteen J 0, Schatz G G and Van Duyne R P 1996 A surface-enhanced hyper-Raman and surface-enhanced Raman scattering study of trans-1,2-bis(4-pyridyl)ethylene adsorbed onto silver film over nanosphere electrodes. Vibrational assignments experiments and theory J. Chem. Phys. 104 4313-26... [Pg.1228]

Another example illustrating the greater reactivity of organolithium compounds is the preparation of the otherwise difficultly accessible esters of 2-pyridyl-acetlc acid by the following series of reactions from a-picoline ... [Pg.929]

The synthesis of 3-phenyl-]-(2-pyridyl)-2-propen-]-one (2.4c) via an aldol reaction of 2-acetylpyridine with benzaldehyde has been described in the literature ". O jmpound 2.4a-e have been prepared in high yields, using slightly modified versions of these literature procedures. [Pg.50]

It is obvious that the reaction is accelerated markedly by water. However, for the first time, the Diels-Alder reaction is not fastest in water, but in 2,2,2-trifiuoroethanol (TFE). This might well be a result of the high Bronsted acidity of this solvent. Indirect evidence comes from the pH-dependence of the rate of reaction in water (Figure 2.1). Protonation of the pyridyl nitrogen obviously accelerates the reaction. [Pg.52]

A quantitative correlation between rate and equilibrium constants for the different metal ions is absent. The observed rate enhancements are a result of catalysis by the metal ions and are clearly not a result of protonation of the pyridyl group, since the pH s of all solutions were within the region where the rate constant is independent of the pH (Figure 2.1). [Pg.59]

Ni(N03)2 6H20, Cu(N03)2 3H20, Zn(N03)2-4H20 and KNOj were of the highest purity available. Substituted 3-phenyl-l-(2-pyridyl)-2-propene-ones (2.4a-e) were prepared by an aldol condensation of the corresponding substituted benzaldehyde with 2-acetylpyridine, following either of two modified... [Pg.64]

In Chapter 2 the Diels-Alder reaction between substituted 3-phenyl-l-(2-pyridyl)-2-propene-l-ones (3.8a-g) and cyclopentadiene (3.9) was described. It was demonstrated that Lewis-acid catalysis of this reaction can lead to impressive accelerations, particularly in aqueous media. In this chapter the effects of ligands attached to the catalyst are described. Ligand effects on the kinetics of the Diels-Alder reaction can be separated into influences on the equilibrium constant for binding of the dienoplule to the catalyst (K ) as well as influences on the rate constant for reaction of the complex with cyclopentadiene (kc-ad (Scheme 3.5). Also the influence of ligands on the endo-exo selectivity are examined. Finally, and perhaps most interestingly, studies aimed at enantioselective catalysis are presented, resulting in the first example of enantioselective Lewis-acid catalysis of an organic transformation in water. [Pg.82]

This goal might well be achieved by introducing an auxiliary that aids the coordination to the catalyst. After completion of the Diels-Alder reaction and removal of the auxiliary the desired adduct is obtained. This approach is summarised in Scheme 4.6. Some examples in which a temporary additional coordination site has been introduced to aid a catalytic reaction have been reported in the literature and are described in Section 4.2.1. Section 4.2.2 relates an attempt to use (2-pyridyl)hydrazone as coordinating auxiliary for the Lewis-acid catalysed Diels-Alder reaction. [Pg.111]

Inspired by the work of Burk and Feaster ) we attempted to use (2-pyridyl)hydrazine (4.36) as a coordinating auxiliary (Scheme 4.10). Hydrazines generally react effidently with ketones and aldehydes. Hence, if satisfactory activation of the dienophile can be achieved through coordination of a Lewis acid to the (2-pyridyl)hydrazone moiety in water. Lewis-add catalysis of a large class of ketone- and aldehyde-activated dienophiles is antidpated Subsequent conversion of the hydrazone group into an amine functionality has been reported previously by Burk and Feaster ... [Pg.113]

Reaction of dnnamaldehyde 4.35 with (2-pyridyl)hydrazine (4.36) yielded the desired hydrazone 4.37. As anticipated, this compound coordinates readily to copper(II)nitrate in aqueous solution as... [Pg.113]

Pyridyl)hydrazine (Aldrich), 4-acetylpyridine (Acros), N,N,N -trimethylethylenediamine (Aldrich), methylrhenium trioxide (Aldrich), InQj (Aldrich), Cu(N0j)2-3H20 (Merck), Ni(N03)2-6Il20 (Merck), Yb(OTf)3(Fluka), Sc(OTf)3 (Fluka), 2-(aminomethyl)pyridine (Acros), benzylideneacetone (Aldrich), and chalcone (Aldrich) were of the highest purity available. Borane dimethyl sulfide (2M solution in THE) was obtained from Aldrich. Methyl vinyl ketone was distilled prior to use. Cyclopentadiene was prepared from its dimer immediately before use. (R)-l-acetyl-5-isopropoxy-3-pyrrolin-2-one (4.15) has been kindly provided by Prof H. Hiemstra (University of Amsterdam). [Pg.119]

Finally, in Chapter 5, micellar catalysis of Diels-Alder reactions is discussed. In view of the nonpolar nature of most Diels-Alder reactants, efficient micellar catalysis of this reaction was anticipated However, this has not been observed. The results for the Diels-Alder reaction between cyclopentadiene and substituted 3-phenyl-l-(2-pyridyl)-2-propene-l-one dienophiles, discussed in... [Pg.162]

In summary, the work in this thesis provides an overview of what can be achieved with Lewis-acid and micellar catalysis for Diels-Alder reactions in water as exemplified by the reaction of3-phenyl-l-(2-pyridyl)-2-propene-l-ones with cyclopentadiene. Extension of the observed beneficial effect of water on rates and particularly enantioselectivities to other systems is envisaged. [Pg.163]

Chapter 2 describes the results of the first detailed study of Lewis-acid catalysis of a Diels-Alder reaction in water. Substituted 3-phenyl-l-(2-pyridyl)-2-propen-l-one dienophiles (la-gin Scheme 1) were found to coordinate to Co, Cu" and Zn ions in aqueous solution. This process forms... [Pg.173]

The cross-coupling of aromatic and heteroaromatic rings has been carried out extensively[555]. Tin compounds of heterocycles such as oxazo-lines[556,557], thiophene[558,559], furans[558], pyridines[558], and seleno-phenes [560] can be coupled with aryl halides. The syntheses of the phenylo.xazoline 691[552], dithiophenopyridine 692[56l] and 3-(2-pyridyl)qui-noline 693[562] are typical examples. [Pg.229]

Methyl-5-(4-pyridyl)-7-aza- 2-Araino-3-iodo-6-methyl-,S- (4-pyridyl)pyridine Trimethylsilylethyne. Pd(PPh,)jCl4, Cut 96,40 ... [Pg.22]

Alky]-5-imino-3-methy -A2-l,2,4-thiadiazoIines react exotherm ally at 0°C with dibenzoy] or dimethoxy carbonylacetylenes in tetrahydrofuran to give the 2-alkylaminothiazoles in high yields (1564). The cycio addition reaction of 2-pyridyl isothiocyanates with 1-azirines results in the formation of 2-pyridylaminothiazoles (1565). [Pg.15]

The 5-position is the preferred site for sulfonation (58. 392). This position is more reactive than any of the pyridine ring in. V-[pyridyl-(2)]-thiazolyl-(2)-amine (178) (132, 382, 383). [Pg.75]

These halogenation reactions all take place in the 5-position (408. 409. 430) even when there is a phenyl or a 2-pyridyl (382) substituent on the exocyclic nitrogen. Crystalline perbromides have been isolated (166. 320. [Pg.77]

Treating 5.5 g of 2-amino-4,5-dimethylthiazole HCl with 0.66 g of solid sodium hydroxide 15 min at 220°C yields 53% of 4.4. 5.5 -tetramethyT 2,2 -dithiazolylamine, whose structure w as proved by identification with the produa obtained from the reaction between dithiobiuret and 3-bromo-2-butanone (467). This result is comparable to the reaction between 2-aminopyridine and its hydrochloride to yield bis(pyridyl-2)amine (468). Gronowitz applied this reaction to 2-aminothiazole, refluxing it with its hydrochloride 4 hr in benzene and obtained the dimeric 2-aminothiazole (236). He proposed a mechanism (Scheme 143) that involves the addition of a proton to the 5-position of the ring to give 234. The carbocation formed then reacts on the 5-position of a second... [Pg.85]


See other pages where Pyridyls is mentioned: [Pg.929]    [Pg.62]    [Pg.65]    [Pg.65]    [Pg.66]    [Pg.66]    [Pg.66]    [Pg.75]    [Pg.113]    [Pg.114]    [Pg.120]    [Pg.120]    [Pg.120]    [Pg.164]    [Pg.227]    [Pg.146]    [Pg.25]    [Pg.61]    [Pg.90]    [Pg.79]    [Pg.120]    [Pg.123]    [Pg.142]    [Pg.180]    [Pg.180]    [Pg.180]    [Pg.197]    [Pg.198]   
See also in sourсe #XX -- [ Pg.65 ]

See also in sourсe #XX -- [ Pg.10 , Pg.238 , Pg.257 ]




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1,2,4-Triazole, 4-(2-pyridyl

2 -Pyridyl C-nucleosides

2 -Pyridyl thioglycoside

2- Methyl-l,3-dioxolane, reaction with 2-pyridyl cations

2- Pyridyl methanesulfonic acid

2-(2 pyridyl (quinoline

2-Oxazolines, pyridyl-, lithiation

2-Pyridyl benzoate

2-Pyridyl catalyst, oxidation with

2-Pyridyl cations, reaction with 2-methyl1,3-dioxolane

2-Pyridyl chloroformate

2-Pyridyl disulfide reactive crosslinkers

2-Pyridyl ketone-O-acyloximes

2-Pyridyl ketone-O-acyloximes Grignard reagents

2-Pyridyl ketone-O-acyloximes acylation

2-Pyridyl phosphate, hydrolysis

2-Pyridyl phosphonosulfate hydrolysis

2-Pyridyl phosphonosulfate zinc catalysis

2-Pyridyl platinum complexes, reaction with

2-Pyridyl pyrazoles

2-Pyridyl pyrrolidines

2-Pyridyl selenides

2-Pyridyl sulfones

2-Pyridyl sulfones, anomeric

2-Pyridyl triflates synthesis

2-pyridyl allyl sulfide

2-pyridyl and 3-pyridylzinc bromides

2-pyridyl boronates

2-pyridyl disulfide

2-pyridyl group on silicon

2-pyridyl ring

3- Aminopyridines 3-pyridyl)pyridinium

3- Aminopyridines 3-pyridyl)pyridinium salt

3- Methoxy-2-pyridyl glycosides

3- Pyridyl alkanol

3- Pyridyl alkanols

3- Pyridyl ethyl ketone

3- Pyridyl isocyanide

3- Pyridyl isocyanide O-acyl thiohydroxamate photolysis

3- pyridyl derivatives

3- pyridyl group

3-2 -Pyridyl pyridine

3-Pyridyl alkanol, enantioselective asymmetric

3-Pyridyl alkanol, enantioselective asymmetric autocatalysis

3-pyridyl ketone

4,4 -Bipyridine, formation from 4-pyridyl

4- Methyl-2-pyridyl-pyrimidine

4- Pyridyl thioglycosides

4-pyridyl position

5-(4-Pyridyl(porphyrin

5-Carbamoyl-3-pyridyl alkanol

5-Carbamoyl-3-pyridyl alkanol, asymmetric

6- Methyl-2-pyridyl methanesulfonic

Acid/pyridyl complexes

Alanine 3-pyridyl

Alcohols, pyridyl reaction with

Alkyl pyridyl ketones, reduction

Alkyl-2-pyridyl sulfide

Amides pyridyl

Aryl 2- pyridyl

Aryl 2- pyridyl organometallic reagents

Aryl 2- pyridyl sulfoxides, reactions with

Azetidine pyridyl ethers

Benzyl 2-pyridyl carbonate

Bis pyridyl

Bis pyridyl ligand

Bis(2-pyridyl)benzoquinoxaline (dpb)

Bis(2-pyridyl)quinoxaline (dpq)

Boranes, pyridyl

Copper complexes pyridyl

Di-2-pyridyl carbonate

Di-2-pyridyl disulfide

Di-2-pyridyl ketones

Di-2-pyridyl sulfite

Di-2-pyridyl thionocarbonate

Di-3-pyridyl

Di-a-pyridyl carbonate

Diels-Alder reactions of pyridyl dienophile

Directing group 4-pyridyl

Disulfide exchange pyridyl disulfides

Disulfide formation with pyridyl

Disulfide pyridyl disulfides

Ethyl 2-pyridyl disulfide

Grignard reagents pyridyl, reactions with

Grignard reagents with pyridyl thiolates

Hydrogen bond carboxyl-pyridyl

Hydrogen bond pyridyl

Hydrogen bonding pyridyl

Hydroxamates, O-acyl selenodecomposition synthesis of alkyl 2-pyridyl selenides

Hydroxamates, O-acyl thiocarboxyl radicals from alkyl 2-pyridyl sulfides

Iridium complexes pyridyl

Iron complexes pyridyl

Ketones aryl-pyridyl

Lithium pyridyls

Manganese Complexes for Alkene Oxidation Based on Pyridyl Ligands

Mannosyl pyridyl sulfones

Methanol, pyridyl

Methyl 2-pyridyl

Methyl 2-pyridyl sulphoxides

Methyl Pyridyl Ketone

Methyl pyridyl sulfoxide

Nitrenes 2-pyridyl

Olefins pyridyl-substituted

Phenyl 2-pyridyl ether

Phenyl pyridyl ketone

Phenyl-2-pyridyl ketoxime

Phosphine pyridyl

Platinum-pyridyl-carboxylate

Pyrazyl-pyridyl

Pyridines pyridyl-2-sulfonates

Pyridyl

Pyridyl Disulfide Reagents

Pyridyl Disulfides

Pyridyl N-oxide

Pyridyl Substituents in Preformed Blocks

Pyridyl Ureas and Amides

Pyridyl acrylic acids

Pyridyl alcohol, chiral, Asymmetric

Pyridyl alkali

Pyridyl alkoxides

Pyridyl alkyl ketones

Pyridyl amine

Pyridyl ammonia

Pyridyl aniline

Pyridyl azides

Pyridyl based systems

Pyridyl betaine, nitrocycloaddition reactions

Pyridyl betaine, nitrocycloaddition reactions fulvenes

Pyridyl bipyridyls from

Pyridyl blues

Pyridyl boronic acid

Pyridyl bromide

Pyridyl carbonyl compounds

Pyridyl carboxylic acids

Pyridyl complexes

Pyridyl complexes, protonation state-dependent

Pyridyl diazonium salts, reactions with

Pyridyl disulfide AMCA-HPDP

Pyridyl disulfide immobilized

Pyridyl disulfide reactions

Pyridyl disulfide reactive cross-linkers

Pyridyl disulphides

Pyridyl donor sites

Pyridyl esters

Pyridyl esters, hydrolysis

Pyridyl fragment of pyridomycin

Pyridyl functional groups

Pyridyl functional groups ligands

Pyridyl groups, substituent constants

Pyridyl halide

Pyridyl hydrazines

Pyridyl hydrogen sulphide

Pyridyl hydrolysis

Pyridyl indoles from

Pyridyl ketenes

Pyridyl ligand

Pyridyl methyl pyrrolidine

Pyridyl methylsulfinyl benzimidazole

Pyridyl nitrous acid

Pyridyl oxidation

Pyridyl oxides

Pyridyl oxiranes

Pyridyl phenol

Pyridyl phosphorus halides

Pyridyl pyrazole

Pyridyl pyridine 1-oxides

Pyridyl pyridinium salts

Pyridyl radical cation

Pyridyl radicals

Pyridyl reactions with

Pyridyl reactions with aromatics

Pyridyl stable

Pyridyl stannanes

Pyridyl sulfone

Pyridyl sulfonyl group

Pyridyl sulfoxides

Pyridyl sulfoxides reaction with Grignard reagents

Pyridyl sulphones

Pyridyl sulphoxides

Pyridyl thiocyanates

Pyridyl thioesters

Pyridyl thioesters lactones

Pyridyl thiols

Pyridyl triflate

Pyridyl triflate coupling reactions

Pyridyl triflates

Pyridyl unit

Pyridyl water

Pyridyl)-2 -propanol

Pyridyl)methylcyclohexanol

Pyridyl-1,2,3,6-tetrahydropyridine

Pyridyl-1,2,3-triazoles

Pyridyl-Propionic Acid

Pyridyl-acyl hydrazone

Pyridyl-based ligands

Pyridyl-porphyrin binding

Pyridyl-quinoline-based complexes

Pyridyl-type ligands

Pyridyls 2-pyridyl group

Quinolines pyridyl

Reaction pyridyl disulfides

Rhenium-pyridyl complex

Rhodium complexes pyridyl

S)-(-)-4-(2-Methylpropyl)-2-(2-pyridyl)-2-oxazoline

Selenides, alkenyl pyridyl

Selenides, alkyl 2-pyridyl

Selenides, alkyl 2-pyridyl synthesis

Selenides, nor-alkyl-2-pyridyl

Selenides, nor-alkyl-2-pyridyl synthesis

Sulfides, 2-pyridyl

Sulfides, 2-pyridyl coupling reactions

Sulfides, 2-pyridyl with Grignard reagents

Sulfides, alkyl 2-pyridyl synthesis

Supramolecular Assembly Using Peripheral Pyridyl-Substituents

Tetra-pyridyl-porphyrin

Uranium-pyridyl

Ureas pyridyl

With Pyridyl Derivatives

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