Quaternization of quinazoline with methyl iodide

Bunting, John W.; Meathrel, William G.

doi:10.1139/v70-576

Cited by 19 publications

(13 citation statements)

References 10 publications

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“…The reactivity also sharply increases for dications when compared with those of monocations. Whereas pK R+ values of 1-methyl-1,5-70, 6-methyl-1,6-71, 7-methyl-1,7-72 and 1-methyl-1,8-naphthyridium 73 ions have pK R+ between 12.3 and 13.1 86 , with 2-methyl-2,7-naphthyridinium cation 74 having pK R+ = 10.58 99 , the dications of naphthyridines with two methyl groups on nitrogens 1,5 75 (pK R+ = 4.93), 1,6 76 (pK R+ = 2.1) and 2,7 77 (pK R+ = 3.84) are much more reactive. In these cases the addition of the hydroxide ion occurs 99 on carbon 4.…”

Section: Issn 1424-6376mentioning

confidence: 99%

“…Whereas pK R+ values of 1-methyl-1,5-70, 6-methyl-1,6-71, 7-methyl-1,7-72 and 1-methyl-1,8-naphthyridium 73 ions have pK R+ between 12.3 and 13.1 86 , with 2-methyl-2,7-naphthyridinium cation 74 having pK R+ = 10.58 99 , the dications of naphthyridines with two methyl groups on nitrogens 1,5 75 (pK R+ = 4.93), 1,6 76 (pK R+ = 2.1) and 2,7 77 (pK R+ = 3.84) are much more reactive. In these cases the addition of the hydroxide ion occurs 99 on carbon 4. The readily formed pseudobases in aqueous solutions reflect the extreme electron deficiency of the heteroaromatic dications produced by quaternization of both ring nitrogens of the naphthyridines …”

Section: Issn 1424-6376mentioning

confidence: 99%

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Additions of water, hydroxide ions, alcohols and alkoxide ions to carbonyl and azomethine bonds

Zuman¹

2002

Arkivoc

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In this review are discussed equilibria involved in nucleophilic additions of H 2 O, HO -, ROH, and RO -(where R is an alkyl) to compounds containing carbonyl and azomethine bonds. These reactions result in a formation of covalent bonds between the heteroatom of the nucleophile and the carbon of the carbonyl double bond. After a brief summary of reactions resulting in additions to aliphatic carbonyl compounds, attention is paid to additions to benzaldehydes and formyl aromatic heterocycles. Equilibria involving additions to pyridoxal and some related compounds are dealt with in some detail. Discussion of additions of stated nucleophiles to azomethine bonds is practically restricted to additions to C=N bonds in heterocyclic rings. The reactivity of nucleophiles in such additions depends on the number of heteroatoms (in particular nitrogen) in the attacked ring, as well as on the number and position of substituents in such rings. In polynuclear compounds the reactivity depends on the number and kind of annelled rings, on the number and mutual position of heteroatoms and on the kind, number and position of substituents. In particular additions to pyrimidines, quinazolines, 1,2,4-and 1,3,5-triazines, pteridines and other heterocycles with four nitrogens, as well as 8-azapurines are mentioned.

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Section: Issn 1424-6376mentioning

confidence: 99%

Section: Issn 1424-6376mentioning

confidence: 99%

Additions of water, hydroxide ions, alcohols and alkoxide ions to carbonyl and azomethine bonds

Zuman¹

2002

Arkivoc

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“…1. The appearance of a broad absorption maximum in the vicinity of 450-500 nm is characteristic of 1,2-dihydro-5-nitroisoquinoline derivatives (14,15). Confirmation of the structure of the product of this reaction was obtained upon the isolation of a red oil from solutions containing higher concentrations of this cation.…”

Section: Resultsmentioning

confidence: 77%

“…Since this isoquinolinium cation undergoes hydroxide ion addition to form the pseudobase 3 with pKR+ 11.7 (14), pseudobase formation competes with the formation of 2 in more basic aqueous solutions. Cation-pseudobase equilibration is essentially instantaneous (15), and is much faster than the reaction of the 2-methyl-5-nitroisoquinolinium cation with Can.…”

Section: Resultsmentioning

confidence: 99%

A rate and equilibrium study of the addition of acetone enolate ion to the 2-methyl-5-nitroisoquinolinium cation in aqueous solution

Bunting¹,

Tam²

1986

Can. J. Chem.

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Rate and equilibrium constants for the reaction between acetone and the 2-methyl-5-nitroisoquinolinium cation to give l-acetonyl-l,2-dihydro-2-methyl-5-nitroisoquinoline (2) have been evaluated over the pH range 10.0-1 1.3 in aqueous solutions at 25°C. This reaction is shown to occur under much milder conditions (temperature, pH) and in much shorter reaction times than 1 I previously used for the synthesis of this adduct. Analogous data for the reaction of hexadeuteroacetone with this heterocyclic 1 cation are also presented. The formation of 2 is shown to be first order in each of acetone, isoquinolinium cation, and hydroxide ion, and is not catalyzed by carbonate buffer species. These data are consistent with the rate-determining attack of the acetone enolate anion upon the isoquinolinium cation. The microscopic reverse of this reaction is the uncatalyzed decomposition of 2, which is consistent with the observed pH independence of the first-order rate constant for this process. Quantitative comparisons of rates and equilibria for the addition of hydroxide ion and acetone enolate ion to this isoquinolinium cation and to substituted benzaldehydes are now available. Chem. 64,973 (1986) OpCrant en solutions aqueuses, a 25°C et dans un lntervalle de pH allant de 10,O 11,3, on a CvaluC les constantes de vitesse et les constantes d'kquilibre pour la rkaction entre lYacCtone et le catlon mkthyl-2 nitro-5 isoquinolkinium qui conduit a l'acktonyl-1

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“…If general acid catalysis operates in the hydrolysis of alkyl and aryl galactosides, then it is reasonable to suppose that general base catalysis by the same group operates during the hydrolysis of the galactosyl- enzyme. But protonation of this general base catalytic group cannot be detected above pH 6 [16]. There are at least three possible explanations for this, as follows.…”

Section: Results and Discussion Acryl Galactosidesmentioning

confidence: 96%

Dependence upon pH of Steady‐State Parameters for the β‐Galactosidase‐Catalysed Hydrolyses of β‐D‐Galactopyranosyl Derivatives of Different Chemical Types

Withers¹,

Sinnott²,

Jullien³

et al. 1978

European Journal of Biochemistry

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The effect of pH upon the p-galactosidase-catalyzed hydrolyses of aryl galactosides is essentially similar for each of the three steps of their hydrolysis. It differs markedly from that on the hydrolysis of galactosyl pyridinium salts ; these proceed through a 'non-bottleneck' pathway.While pH increase abolishes the rate of every step of the reaction for aryl galactosides, it favors the first step of hydrolysis of the galactosyl pyridinium salts, which supports the hypothesis that catalysis of these compounds originates largely in non-covalent interactions.The effect of change in pH upon the kinetic parameters of an enzyme-catalysed process is widely studied. However, whilst results are experimentally easy to obtain, their interpretation is more complicated. Bloomfield and Alberty [1] derived some simplified equations, and these are often applied without knowledge as to whether the necessary simplifying assumptions are indeed correct. Knowles has widely discussed this question [ 2 ] . The interpretation of such results should, in the case of Escherichia coli /3-galactosidase, be facilitated by the use of substrates whose hydrolysis can be studied by other methods. THEORYThe action of j-galactosidase upon a Pa-galactopyranosyl derivative can be described by the following scheme [3 -81 :where E . GalX* is a complex resulting from the conformational step [7,8]. Which step is rate-deterEnzyme. 8-Galactosidase (EC 3.2.1.23) mining, and whether the k + 2 or k + 4 pathway is taken from the first ES complex, can be determined by criteria other than the dependence of kinetic parameters upon pH. For some substrates, such evidence has been obtained. Degalactosylation Rate-LimitingAt low temperature [9] or with the product of a mutant Z gene [lo], a 'burst' of aglycone is observed which is evidence of degalactosylation ( k , 6 k -5/ki s) being rate-limiting. Under ordinary conditions, however, this process is too fast for conventional stoppedflow work and degalactosylation can be shown to be rate-limiting by methanol competition. Addition of methanol, which is about 100 times more nucleophilic than water towards the galactosyl-enzyme [3,6], causes an increase in kcat, and a pronounced increase in K , only if degalactosylation is the slow step: if it is not, methanol causes a slight decrease in k,,, and a modest increase in K , [3,5 -71. Degalactosylation is associated with an a-deuterium kinetic isotope effect of 1.25 [S]; this is one piece of evidence for the complex, ion-paired nature of the galactosyl-enzyme [S]. k, 2 Rate-LimitingThe non-covalent rearrangement of the ES complex is characterised by the absence of both an CIdeuterium kinetic isotope effect and any but the weak-

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Quaternization of quinazoline with methyl iodide

Abstract: Contrary to previous reports, the methylation of quinazoline with methyl iodide has been shown to produce both 1-methylquinazolinium iodide and 3-methylquinazolinium iodide. These quaternary salts are formed in the ratio of 5:1 in favor of the latter isomer.

Cited by 19 publications

References 10 publications

Additions of water, hydroxide ions, alcohols and alkoxide ions to carbonyl and azomethine bonds

Additions of water, hydroxide ions, alcohols and alkoxide ions to carbonyl and azomethine bonds

A rate and equilibrium study of the addition of acetone enolate ion to the 2-methyl-5-nitroisoquinolinium cation in aqueous solution

Dependence upon pH of Steady‐State Parameters for the β‐Galactosidase‐Catalysed Hydrolyses of β‐D‐Galactopyranosyl Derivatives of Different Chemical Types

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