Diiodo oxide

Addition of halogens proceeds stepwise, sometimes accompanied by oxidation. Iodine forms 2,3-diiodo-2-butene-l,4-diol (53). Depending on conditions, bromine gives 2,3-dibromo-2-butene-l,4-diol, 2,2,3,3-tetrabromobutane-l,4-diol, mucobromic acid, or... 

Displacement of aromatic halogen in 2,4-diiodo-estradiol with tritiated Raney nickel yields 2,4-ditritiated estradiol. Aromatic halogen can also be replaced by heating the substrate with zinc in acetic acid-OD or by deuteration with palladium-on-charcoal in a mixture of dioxane-deuterium oxide-triethylamine, but examples are lacking for the application of these reactions in the steroid field. Deuteration of the bridge-head position in norbornane is readily accomplished in high isotopic purity by treatment of the... 

Diiodo-l,2-benzenediamine gave 5,8-diiodo-2-(pyridin-2-yl)quinoxaline (131, R = I) [2-(bromoacetyl)pyridine HBr, Me2SO, 60°C, 1 h 20% aerial or solvent oxidation ] 172 perhaps by a comparable mechanism, 1,2-benzenediamine... 

The (EDT-TTF-I)2Br salt described above [36] and the 1 1 (TTFI4)I salt reported by Gompper [51] were the only structurally characterized salts with simple halide anions until Imakubo recently described an extensive series of Cl" and Br" salts from several ortho-diiodo tetrathiafulvalene, tetraselena-fulvalene and dithiadiselenafulvalene derivatives (Scheme 8) [62], The X-ray crystal structure analysis of the nine salts described there show a variety of halogen bonded motifs, demonstrating the adaptability of the supramolecu-lar interactions to other structural requirements imposed by the nature of the heteroatoms (O, S, Se) in the TTF frame. Indeed, in (EDT-TTF-l2)2X-(H20)2 (X = Cl, Br), a bimolecular motif (Fig. 6) associates two partially oxidized EDT-TTF-I2 molecules with one Br" anion and one water molecule. 

Several compounds can be oxidized by peroxidases by a free radical mechanism. Among various substrates of peroxidases, L-tyrosine attracts a great interest as an important phenolic compound containing at 100 200 pmol 1 1 in plasma and cells, which can be involved in lipid and protein oxidation. In 1980, Ralston and Dunford [187] have shown that HRP Compound II oxidizes L-tyrosine and 3,5-diiodo-L-tyrosine with pH-dependent reaction rates. Ohtaki et al. [188] measured the rate constants for the reactions of hog thyroid peroxidase Compounds I and II with L-tyrosine (Table 22.1) and showed that Compound I was reduced directly to ferric enzyme. Thus, in this case the reaction of Compound I with L-tyrosine proceeds by two-electron mechanism. In subsequent work these authors have shown [189] that at physiological pH TPO catalyzed the two-electron oxidation not only L-tyrosine but also D-tyrosine, A -acetyltyrosinamide, and monoiodotyrosine, whereas diiodotyrosine was oxidized by a one-electron mechanism. 

Chlorination of the isomeric (3) led to similar C-2 mono- and C-2, C-5 di-substituted products (91) and (92) no C-3 substituted product was identified in the mixture by GC. In comparison with bromination and chlorination considerably less is known about the iodination of (3) and (7). Rather unstable C-2 substituted derivatives (93) and (94) were obtained when iodination was carried out in the presence of mercury(II) oxide. The assigned structures were confirmed by standard conversion to the known carboxylic acids. During the iodination of (3), diiodo derivative (95) was also observed (76AHC(19)123). 

The third known method of synthesis of the heterocycles 82 is exemplified by the preparation of 4,4-diiodo-l-oxa-4-telluracyclohexane 84 on heating bis(2-iodoethyl)ether with powdered tellurium (45JCS11). It has an analogy in the synthesis of dimethyl tellurium diiodide from methyl iodide and elemental tellurium (20JCS86), but is characterized by a rather low yield (10-13%) of product 84 because of partial decomposition of the initial oxide under the reaction conditions. When bis(2-chloroethyl)ether and Nal were used instead of bis(2-iodoethyl)ether and the reaction was... 

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