Amino compounds, methylation

Diphenyl-2H-imidazoles 120 have been shown to form methosalts 121 in high yields (Scheme 29) ethyl iodide, however, gave only small amounts of ethosalts. In 4-amino compounds, methylation occurs at the ring N-3. ... 

The 3-amino group brings a second nucleophilic center in these structures thus 2-imino-3-amino-4-methyl-4-thia201ine (409) reacts with methyl diloroformate to give the bicyclic compound (410) (Scheme 234). Other thiazolo-s-triazoles of the [3.2-l>] type have been obtained by... 

Does the NMR spectrum shown in Figure 22 10 correspond to that of 1 amino 2 methyl 2 propanol or to 2 ammo 2 methyl 1 propanoD Could this compound be prepared by reaction of an epoxide with ammonia" ... 

Nltropropane. As much as 9100 t of 2-nitropropane once were consumed for use in coatings annually. Concern about toxicity and a general movement to low volatile organic compound (VOC) coatings have resulted in almost the complete disappearance of this use for 2-nitropropane. However, derivatives such as 2-meth5l-2-nitro-l-propanol (used in tire cord adhesive) and 2-amino-2-methyl-l-propanol (a pigment dispersant and buffer), have served as an outlet for 2-nitropropane production. 

A similar series of reactions can be carried out for the 6-methyl series, (13) and (15), where catalytic reduction affords the amino compounds, ie (17,... 

The effect of substituents on the reactivity of heterocyclic nuclei is broadly similar to that on benzene. Thus mem-directing groups such as methoxycarbonyl and nitro are deactivating. The effects of strongly activating groups such as amino and hydroxy are difficult to assess since simple amino compounds are unstable and hydroxy compounds exist in an alternative tautomeric form. Comparison of the rates of formylation and trifiuoroacetylation of the parent heterocycle and its 2-methyl derivative indicate the following order of sensitivity to substituent effects furan > tellurophene > selenophene = thiophene... 

The American authors suggested (X) or (XI), already considered by Spath and Nikawitz for vasicine, and support for a formula of type (XI) was provided by Spath, Kuffner and Platzer, who, by condensing o-nitrobenzyl chloride with methyl y-aminobutyrate to o-nitrobenzyl-pyrrolidone (XII), reduction of this to the amino-compound (XII NOa —> NHj) and ring-closure in presence of phosphoryl chloride obtained the base d -pegene (XIII), m.p. 99-100°, identical with the product formed by the reduction of deoxychloropeganine. The same substance... 

In comparison with mercapto-, hydroxy-, and amino-pyridines, methylpyridines should show an even greater tendency to exist in the methyl form [instead of as pyridmethines (297)] than do the amino compounds to exist as such. If the methyl carbon atom carries an electron-withdrawing group, it might be expected that structures of type 297 would be stabilized. Fused benzo groups should also tend to stabilize the methine form, and tautomerism involving 298 has, in-... 

Aminopyrimidine is the only monosubstituted derivative studied in which the position of quaternization is ambiguous. Methyl iodide and the 4-amino compound react slowly in 2-ethoxyethanol at 100° to give the N-1 salt (42 R = H), whereas 5-aminopyrimidine and... 

Lieber et have come to the same conclusion by an investigation of the ultraviolet spectra and dipole moments of 5-amino-, 5-methyl-amino-, and 5-dimethylamino-l, 2,3,4-thiatriazole. The dimethylamino derivative, in which no tautomerism is possible, shows the same characteristic absorption near 250 m/A as the unsubstituted compound and the monomethyl derivative. The dipole moments of the three compounds differ very little. These moments are quite large (5.8 Debye), showing that ionic resonance forms of type 9 contribute considerably to the structure of these compounds. 

Aminoquinoxaline exists predominantly as such rather than in the tautomeric imino form. This is indicated by a comparison of the basic strength of the 2-amino compound (pKo 3.90) and those of its fixed methylated tautomers, 2-dimethylaminoquinoxaline pKa 3.72) and l-methylquinoxalin-2-oneimine (pfCn 8.70). The ultraviolet spectrum of the neutral molecule of 2-dimethylaminoquinoxaline shows the expected bathochromic shifts compared to that of 2-aminoquinoxaline these spectra differ from the ultraviolet spectrum of the neutral molecule of l-methylquinoxalin-2-oneimine (Fig. 1). The mono-cations (68) and (69) derived from 2-aminoquinoxaline and l-methylquinoxalin-2-oneimine have a similar chromophoric system and show almost identical ultraviolet absorption (Fig. 2). 

Methylations—lactams, thiolactams, amino compounds, and enols. 

D. Methylation of Heterocyclic Amino Compounds 1. Cyclic Enamines... 

Although direct nitration was not possible, 2-amino-4-methylselena-zole can be directly brominated by treatment with bromine in carbon tetrachloride, the hydrogen bromide salt of 2-amino-4-methyl-5-bromoselenazole, mp 180°C (decomp.) is formed. However, all attempts to obtain the free base from this salt failed and led to complete decomposition. In this bromination, an equivalent quantity of bromine must be used excess also leads to complete destruction of the molecule. From the decomposition products an oily compound can be detected similar to bromoacetone. ... 

The action of nitrous acid on the benzodiazepine A -oxide 38 gives the nitrosoamino derivative 39,234 which reacts with alcohols, ethanethiol and various amino compounds, such as hydrazines and guanidine, by replacement of the methyl(nitroso)amino group.235 Reaction with aziridine affords the aziridinyl compound 40f or the 2-(aziridin-l-yl)ethylainino derivative 40g, depending on the conditions. 

Balli and Felder (1978) and Balli and Ritter (1981) showed that diazo transfer can be applied advantageously to the diazotization of sufficiently nucleophilic heteroaromatic compounds such as 5-hydroxy- and 5-amino-3-methyl-l-phenyl-pyrazole if 3-ethyl-2-azido-benzthiazolium tetrafluoroborate (2.50) is used as diazo transfer reagent (for other applications of this diazo transfer reagent see Zollinger, 1995, Secs. 2.6-2.8). The diazonio group is introduced in the 4-position (2.51). 

As shown by Heindel and Corley (1979), ring closure also takes place if the nucleophilic nitrogen is part of a heterocycle, as in the diazotization of 5-amino-3-methyl-2-H-l,2,4-benzothiadiazine-l, 1-dioxide (6.50). In the tricyclic compound 6.51 formed initially, the thiadiazinedioxide ring is opened rapidly in water, forming 1-acetyl-7-aminosulfonyl-l-i/-benzo-l,2,3-triazole (6.52). 

Katritzky et al.508 have measured rates of deuteration of aminopyridine by deuterated sulphuric acid (Table 146), and for the 4-amino and 2-amino-5-methyl compounds, the general increase in rate with increasing acidity, dlogkjd (—H0) 0.6, shows reaction to be occurring on the conjugate acids. For the latter compound this is only true at acidities > —H0 = 4.0, below which rates are relatively independent of acidity indicating reaction on the free base. For the 2,6-dichloro... 

D. Miscellaneous.—A further study of the reactions of diphenyl-phosphine oxide with tetracyclone has confirmed that the reaction yields the oxide (30) under mild, basic conditions, and that the reaction is thermally reversible. The displacement of halogen from phosphorus by amino-compounds has been used in the synthesis of a number of aminofluoro-phosphine oxides (31), and of A-methyl-AA-bis(dichlorophosphinyl)-amine (32). ... 

The principal degradation products of bifenox are the free acid, 5-(2,4-dichlorophenoxy)-2-nitrobenzoic acid, and the amino derivatives, methyl 5-(2,4-dichlorophenoxy)anthranilate and its free acid, in flooded soil. A free acid is observed in nonflooded soil. When [ " C]chlomethoxfen was used to treat rice field soil, chlomethoxfen was extensively transformed into unextractable products with organic solvents however, the amine, the A-demethylated compound and the formyl-amino and acetylamino compounds were isolated and identified as the metabolites of chlomethoxfen. ... 

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