Group oxygen reaction with

Alkali metal A metal in Group 1 of the periodic table, 31 hydrogen reactions with, 542 oxygen reactions with, 543-544 reactions of, 541t, 552q water reactions with, 542... 

Oxygenation of a silane. In the course of an anthracyclinone synthesis, Vedejs and Pribish2 found that a benzylic trimethylsilane can be converted into a hydroxyl group by reaction with TASF in the presence of oxygen and trimethyl phosphite (2 — 3,95% yield). The conversion is considered to involve formation of a benzylic... 

If the benzylidene acetal ring spans the oxygen atoms of two erstwhile secondary hydroxyl groups, the reaction with N-bromosuc-cinimide usually affords isomeric, bromodeoxy sugar benzoates. Thus, for example, the reaction with methyl 2,3-0-benzylidene-5-0-methyl-/3-D-ribofuranoside (106) afforded145 an approximately 1 1 mixture of the bromides 109 and 108, presumably by way of attack on C-2 and C-3 of the benzoxonium intermediate 107 by bromide ion. 

The stereochemical outcome of these electrophilic additions is consistent with a transition state in which the metal chelates the oxazolidinone carbonyl and the enolate oxygen. Reaction with an electrophile would, therefore, occur at the less hindered diastereotopic face of the (Z)-enolate, away from the shielding methyl groups of the auxiliary (Figure 24.6). Because both enantiomers of oxazolidinone 108 are equally available, the direction of the asymmetric induction can be controlled by proper choice of the absolute stereochemistry of the chiral auxiliary.106... 

The participation by metal catalysts in autoxidations may be divided into four main groups (a) reaction with peroxides (h) reaction with substrate (c) reaction with oxygen (d) reaction with alkoxy and alkylperoxy radicals. The latter (d) leads to inhibition rather than to catalysis. Each of these types of participation will be discussed in the following sections. 

Similar to homolytic mechanisms, the heterolytic reactions can be divided into three groups (i) reactions with hydroperoxides, (ii) activation of molecular oxygen, and (iii) direct reaction of metal complexes with substrate. 

The oxygen functions in pyrido[2,3-t/]pyrimidin-4(3/f)-one and in pyrido[2,3-t/]pyrimidine-2,4(l/f,3/7)-dione (15) have been replaced by sulfanyl groups on reaction with phosphorus pentasulfide in Tetralin.79... 

The development of fluorescent probes for detection of reactive oxygen species (ROS) has become an active research field. Probe 30 is a BODIPY-based probe bearing the reaction site of o-phenylenediamine toward NO. It shows fluorescence at 500 nm with low quantum yield due to the PET mechanism. The conversion of o-phenylenediamine into a benzotriazole group upon reaction with NO elicits a remarkable fluorescence enhancement (Scheme 7.26). 

STEPS 1-2 OF FIGURE 22.3 PHOSPHORYLATION AND ISOMERIZATION Glucose is first phosphorylated at the C6 hydroxyl group hy reaction with ATP in a process catalyzed hy hexokinase. As noted in Section 20.1, the reaction requires Mg + as a cofactor to complex with the negatively charged phosphate oxygens. 

Phenol condenses with phthahc anhydride in the presence of concentrated sulphuric acid or anhydrous zinc chloride to yield the colourless phenolphthalein as the main product. When dilute caustic alkah is added to an alcoholic solution of phenolphthalein, an intense red colouration is produced. The alkali opens the lactone ring in phenolphthalein and forms a salt at one phenolic group. The reaction may be represented in steps, with the formation of a h3q)othetical unstable Intermediate that changes to a coloured ion. The colour is probably due to resonance which places the negative charge on either of the two equivalent oxygen atoms. With excess of concentrated caustic alkali, the first red colour disappears this is due to the production of the carbinol and attendant salt formation, rendering resonance impossible. The various reactions may be represented as follows ... 

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