5-Amino-3-methylthio- -4-oxid

Pteridine-4,7-dione, 8-methyl-2-methylthio-oxidation, 3, 299 Pteridine-4,7-dione, 2-methylthio-reactions, 3, 296 Pteridine-6,7-dione, 2-amino-synthesis, 3, 293... 

The alkylthio group is replaceable by nucleophiles. The positions 7 and 4 react under mild conditions in that order the 2-alkylthio functions require more drastic treatment. Conversion of l-methyl-4-methylthiopteridin-2-one (157) into the 4-methylamino derivative (158) can be achieved by stirring with methylamine at room temperature (equation 48). The reactivity of an alkylthio group can often be further enhanced by oxidation to the corresponding sulfoxide and sulfone. Thus, reaction of l,3-dimethyl-7-methylthiolumazine (160) with m-chloroperbenzoic acid yields 7-methylsulfinyl- (161) and 7-methylsulfonyl-l,3-dimethyllumazine (162 equation 49) (82UP21601). 4-Amino-2-methylthio-7-... 

The / -(methylthio)phenyl ester has been prepared from an A-protected amino acid and 4-CH3SC6H4OH (DCC, CH2CI2, 0°, 1 h 20°, 12 h, 60-70% yield). The p-(methylthio)phenyl ester serves as an unactivated ester that is activated on oxidation to the sulfone (H2O2, AcOH, 20°, 12 h, 60-80% yield), which then serves as an activated ester in peptide synthesis. ... 

Of the twenty amino acids that are normally found in proteins, only two contain sulfur, cysteine and methionine. Cysteine has long been recognized as being easily oxidized and this oxidation is associated with the loss of biological activity of many proteins. In recent years, it has been shown that methionine also shares these characteristics. Methionine was first isolated by Mueller19 and was one of the last amino acids discovered. Its structure was later proven to be y-methylthio-a-aminobutyric acid by Barger and Coyne20 who named the amino acid methionine as a contraction for its chemical name. 

Itoh et al. (151) employed a tetradentate amine and synthesized the complex [Znn(l)(MeCN)]PF6, where 1 represents the monoanion of 2-methylthio-4-ferf-6-[[bis[2-(2-pyridyl)ethyl]amino]methyl]phenol (see Fig. 31 for 1). This complex was chemically [with (NH4)2[Ce(N03)6]) or electrochemically oxidized yielding the (phenoxyl)zinc species Zn1 (1 )(MeCN )]PF6. It displays phenoxyl K-K tran-... 

Scheme 3.30 depicts an intriguing case, when one-electron oxidation of the conformationally constrained exo-2-(carboxy)-en(i(9-2-(ammo)-en(i(9-6-(methylthio)-bicyclo[2.2.1]heptane gives rise to a cation-radical in which an amino- and not a carboxylate group participates in the three-electron bond with sulfur (Glass 1995). 

Diese Aminierung ist auch fur l,2,4-Triazin-4-oxide beschrieben3 die Aminierungspro-dukte (z. B. 5-Amino-3-methyhhio-l,2,4-triazin-4-oxid) werden in einer zweiten Stufe mit Phosphor(III)-chlorid zu den 1,2,4-Triazinen (z.B. 5-Amino-3-methylthio-l,2,4-triazin) deoxygeniert. 

Protection of amino compounds by the 2,4-bis(methylthio)phenoxycarbonyl residue [266] converts them into acid stable entities. Removal of the protecting group can be achieved through oxidation at sulfur such that the resulting bissulfone provides conjoint pathways for ready fragmentation. 

A number of 1,2,4-triazines such as the parent compound, the 3-methylthio, 3-methoxy and 3-amino-6-bromo derivatives add ammonia in liquid ammonia at -44 °C to the N(4) —C(5) bond to give adducts of type (lOl), as was shown by XH and 13CNMR spectroscopy. No reaction was observed with 3-methoxy-l,2,4-triazine 1-oxide (71), other 3-amino-l,2,4-triazines, or compounds with a substituent in the 5-position. As was shown using lsN-enriched ammonia, an equilibrium between the covalent addition products (101) and the open-chain isomers (102) does not occur (78RTC273). 

Oxidation of 3,5-bis(methylthio)-l,2,4-triazines (81) with potassium permanganate afforded the 3-monosulfones (241) which could be hydrolyzed to 5-methylthio-l,2,4-triazin-3-ones (242) (69BSF3670). 6-Benzyl-3-thioxo-l,2,4-triazin-5-one (243) with potassium permanganate afforded the 6-benzoyl-3-sulfonic acid (244) (67BSF2551). Similarly, 5-amino-... 

Irradiation of 1,2,4-triazine 4-oxides (124) led to the deoxygenated products, and also, when position 5 was unsubstituted, to 1,2,4-triazoles (364) (76LA153). 4-Amino-l,2,4-triazin-5-ones (365) are photochemically deaminated. This has been demonstrated, in particular, with the 6-r-butyl-3-methylthio compound (8) which is used as a herbicide... 

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