Pyridone, analogues

Degani et al., 1968). A comparison of the basicity of these compounds with those of the corresponding pyridone analogues (2- and 4-quinolones and 9-acridones) is given in Table 4. The order of basicities for these compounds is NH > S > Se > O. They are all protonated on the carbonyl oxygen. Such is the resonance stabilization of the pyrone cations that they do not accept any further... 

Sengupta, T., Gayen, K. S., Pandit, R, Maiti, D. K. (2012). FeCl3 6H20-catalyzed intermolecular-cascade cyclization of acetoacetanilide aldehyde-tuned synthesis to valuable 2-pyridone analogues. Chemistry - A European Journal, 18, 1905-1909. 

The pyridone analogues (160) of neplanocin have been prepared from a previous intermediate (Vol. 23, p.l96),l78 as has psicoplanocin A (161), a carbocyclic nucleoside combining the structural features of neplanocin A and... 

AminothiaZoles. In contrast to the pyrazolones, pyridones, and indoles just described, aminotliiazoles are used as diazo components. As such they provide dyes that ate more bathochromic than their benzene analogues. Thus aminothiazoles are used chiefly to provide dyes in the red-blue shade areas. The most convenient synthesis of 2-aminothiazoles is by the condensation of thiourea with an a-chlorocarbonyl compound for example, 2-aminothiazole [96-50A-] (94) is prepared by condensing thiourea [62-56-6J with a-chloroacetaldehyde [107-20-0J both readily available intermediates. 

The primary fragmentations of 5-methylsulfonyl-6-phenyl-2-pyridone (41) and its 3,4-dihydro analogue (42) are dominated by the methylsulfonyl substituent and not by the pyridone moiety26. Equation (18) summarizes the most important primary fragmentations and shows that the pyridone ions m/z 186 and 170 yield the pyrrole-type ions m/z 158 and 142 only after the sulfonyl side-chain has been broken off. Since the mass spectrum... 

The Boehringer Ingelheim group chose a pyridone-based core structure to replace the -Glu-Glu-Ile- tripeptide of the generic SH2 domain recognition sequence [130]. From a series of more than 200 analogues, pyridones with mutually different decoration patterns were identified to result in pTyr derivatives with submicromolar affinities (e.g., 55,56) for the Lck SH2 domain [130]. 

Acylation of Hydroxypyridines, Pyridones and their Benzo Analogues 352... 

It is now well established that 2- and 4-pyridone and their benzo analogues exist predominantly in the oxo form, e.g. (101a), rather than the hydroxypyridine form, e.g. (101b) (76AHC(S1)84 63AHC(l)34l). The enaminone system NH—C=C—C=0 is considerably more stable than the alternative iminoenol system N=C—C=C—OH by a factor of... 

The angular annelation of the pyridine and pyrazine rings in 28 have been confirmed by a large coupling constant (9 Hz), and this is believed to be attributable to oz/,4o-interaction of the protons. The same configurations on the 4-pyridone and pyrazine analogue 20 shows Vs 9 = 6Hz and Jz,3 = 1.8 Hz, respectively <2000M293>. 

The formation of a 4-pyridone with simultaneous oxidative elimination has never been observed for 4-substituted pyridinium salts, which is in contrast to the 2-substituted analogues. 

An analogue in which a carboxylic acid attached to the 3 position takes the place of the polar pyridone ring in the previous examples also exhibits antiandrogenic activity. The synthesis starts by reaction of the intermediate (44-1) common to the preceding antiandrogens with phosphorus tribromide. This reagent converts the... 

Meuwly, M., Muller, A. and Leutwyler. S. (2003) Energetics, dynamics and infrared spectra of the DNA base-pair analogue 2-pyridone 2-hydroxypyridine. Phys. Chem. Chem. Phys., 5, 2663-2672. 

Stable anions can be formed by the loss of a proton from /V-unsubstituted pyridones or hydroxypyridines. They are the pyridine analogues of phenolate anions and react very readily with electrophilic agents at N, O or ring carbon (see Section 3.2.1.8.4). 

As discussed in Section 2.4.5.2, hydroxy derivatives of azoles fe.g. 622, 624, 626) are tautomeric with either or both of (i) aromatic carbonyl forms (e.g. 623, 627) (as in pyridones), and (ii) alternative non-aromatic carbonyl forms (e.g. 625, 628). In the hydroxy enolic form (e.g. 622, 624, 626) the reactivity of these compounds toward electrophilic reagents is greater than that of the parent heterocycles these are analogues of phenol. 

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