Phenol 2-amino-4-methoxy

Phenol 2-Amino-4-methoxy- XI/I, 525 Propansanre 3-(2-Pyrryl)- VI/2, 554 Pyridin... 

Auch Li t hi urn a I ana t reduziert die o- und p-standig mit elektronenliefemden Gruppen (z.B. Amino, Dial-kylamino, Methoxy) substituierten aromatischen Aldehyde und Ketone mcist nur unter cncrgischen Bedingun-gen zu Kohlenwasserstoffen (z. B. in Dibutylather mehrere Tage bei 80-90°). Formyl- und Acyl-phenole werden nicht reduziert1. 

Chorionic gonadotropin. Follicle stimulating hormone Urea, Uric add. Bilirubin, Cortisol, n-Maimitol. n-Glucose, Sodium pyruvate, 4-hydroxy-3-methoxy mandelic add, 4-Nitro-phenol, 17 Amino adds in HQ, Angiotensin-I, Tripahnitin, Bone meal (8 elements), Bone ash (8 elements), lithium carbonate Luteinizing hormone. Thyroid stimulating hormone... 

As is also illustrated in Scheme 6.23, the optically enriched amino nitriles can be converted to the corresponding a-amino esters through a four-step sequence (74—> 75). Unlike the aforementioned imine alkylations with alkylzinc reagents, methylation of the phenolic OH is required, since the corresponding o-methoxy aniline is less reactive and affords significantly lower enantioselectivities similar observations are made when aniline is used. 

The one-electron reduction potentials, (E°) for the phenoxyl-phenolate and phenoxyl-phenol couples in water (pH 2-13.5) have been measured by kinetic [pulse radiolysis (41)] and electrochemical methods (cyclic voltammetry). Table I summarizes some important results (41-50). The effect of substituents in the para position relative to the OH group has been studied in some detail. Methyl, methoxy, and hydroxy substituents decrease the redox potentials making the phe-noxyls more easily accessible while acetyls and carboxyls increase these values (42). Merenyi and co-workers (49) found a linear Hammett plot of log K = E°l0.059 versus Op values of substituents (the inductive Hammett parameter) in the 4 position, where E° in volts is the one-electron reduction potential of 4-substituted phenoxyls. They also reported the bond dissociation energies, D(O-H) (and electron affinities), of these phenols that span the range 75.5 kcal mol 1 for 4-amino-... 

The rearrangement reaction continues to be of synthetic utility, often involved in industrial processes. Patent references (e.g. Reference 48) refer to the formation of 4-amino phenols. Often the reactant nitro compound is reduced (to the hydroxylamine) in an acid environment so that the two-stage reaction can be accomplished as a one-pot synthesis. 4-Amino phenol itself 45 can be made in high yield directly from nitrobenzene49 and the 4-methoxy aniline derivative 46 similarly from 2-methylnitrobenzene by hydrogenation in MeOH/H2S0450. 

A number of phenolic ethers of this series show the expected properties. 5-Amino-3-ethoxy-l,2,4-thiadiazole is considerably more soluble in water than its 3-methoxy homolog (3.24 and 0.76 g/100 ml, respectively).88 Their ultraviolet spectra resemble those of the 3-alkyl (or aryl)-5-amino-l,2,4-thiadiazoles.88 3-Alkoxy(or aryloxy)-l,2,4-thiadiazoles are more sensitive towards acids than are the 3-alkyl(or aryl) analogs.88... 

Phenoxazin-3-ones and phenothiazin-3-ones can be prepared by the oxidation of the parent heterocycles in acidic media, but it is often more practical to employ condensation reactions between 2-amino-phenols or -thiols and quinones. Alizarin Green G (263), for example, is obtained from the aminophenol (261) and the 1,2-naphthoquinone (262). Similarly, 2-aminothiophenols (264) and 6-chloro-2-methoxy-l,4-benzoquinone (265) afford phenothiazin-3-ones (266) bearing methoxyl groups at position 1. 

Availability is not the only constraint on substrate consumption. The value of a substrate is also related to the resources needed to convert the molecule into an intermediary metabolite. Thus in aerobic environments, monosaccharides and amino acids are readily consumed under anaerobic conditions, heterotrophic metabolism is largely fueled by small organic acids. Some taxa consume other types of substrates as long as they are reasonably abundant. Important examples include P-proteobacteria that consume phenols, a significant component of DOM inputs originating from plant material, and methylotrophs that consume single carbon compounds produced by anaerobic metabolism, photochemical reactions, and oxidation of methyl and methoxy substituents (Giovannoni and Rappe, 2000). 

An extension of this synthetic route to alkyl-substituted o-amino-phenols gave symmetrically substituted dialkyl phenoxazines, but chloro- and methoxy-substituted o-aminophenols failed to react under similar conditions. 4-Methyl- (or 4-ethyl-)2-aminophenol, by reaction with the corresponding hydrochloride, yielded 2,8-dimethyl-and 2,8-diethylphenoxazine, respectively.8... 

The simpler architecture is the 1,1 -biphenyl scaffold, likewise introduced by Hoveyda and coworkers [19]. The synthesis of the imidazolium salt starts with a chiral diamine and a substituted, achiral biphenyl [82-84], Subsequent introduction of a Mes substituent on the remaining primary amino end and ring closure reaction yields the chiral saturated imidazolium salt after hydrolysation of the methoxy group to liberate the phenolic hydroxy group (see Figure 4.22). Reaction with silver(I) oxide and carbene transfer to a Grubbs (Hoveyda) catalyst sets up the ruthenium catalyst complex. 

The chemical information available through LFER is primarily the reaction constant p, but this value depends upon the substituent constants selected for the construction of the LFER. The u values available are ct, ct", ct" or and Ui, these quantities are listed, for many substituents, in Tables 7-1, 7-3, 7-4, 7-6, and 7-7. A reasonable approach is to plot log k against the substituent constant defined by a standard reaction that is expected to be most like the reaction under study. It is also reasonable to plot log k against several of the ct quantities, seeking the best correlation. [In choosing between two types of substituent constants, it is necessary to make use of substituents for which the two scales (say ct and rr, for example) are not themselves correlated, for otherwise both LFERs will be acceptable. ] The ct or o constants should be applicable to reactions that do not combine reaction sites and para substituents of the + and — type (push-pull systems capable of through resonance) for example, one would not expect ct" or o to provide good correlations for reactions of phenols or anilines substituted with nitro or cyano or for reactions of benzoic acids substituted with amino or methoxy. 

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