Oxidative addition reactions synthesis

This synthetic approach is known from the synthesis of L M(alkene)H compounds from LnM(CO)alkane precursors and can easily be applied to the analogous silyl complexes. The Si—H bond even shows an increased activity for oxidative addition reactions [42, 43]. 

Thioamides are reducing agents. They inhibit thyroid hormone synthesis by inhibiting the peroxidase enzymatic system, which catalyzes oxidation of iodide ions and iodine that are consumed in food, which is necessary for iodination of tyrosine derivatives. Thus they reduce the concentration of free iodine necessary to react with tyrosine derivatives, and they can also block oxidative addition reactions of mono- and diiodtyrosines, which form L-thyroxine and L-triiodothyronin. 

Further chemistry of alkenes and alkynes is described in this chapter, with emphasis on addition reactions that lead to reduction and oxidation of carbon-carbon multiple bonds. First we explain what is meant by the terms reduction and oxidation as applied to carbon compounds. Then we emphasize hydrogenation, which is reduction through addition of hydrogen, and oxidative addition reactions with reagents such as ozone, peroxides, permanganate, and osmium tetroxide. We conclude with a section on the special nature of 1-alkynes— their acidic behavior and how the conjugate bases of alkynes can be used in synthesis to form carbon-carbon bonds. 

The reaction between a low-valent Group VIII metal complex and an alkyl halide belongs to the class known as oxidative addition and has attracted much study and controversy as to the mechanism. Recent evidence suggests free radicals as intermediates in many cases. The oxidative-addition reaction is of widespread occurrence and importance in transition metal chemistry, due in part to its use in synthesis and to its implication in many catalytic systems. In one of its forms it is described by... 

Their advantage over other types of dendrimers is their straightforward synthesis and, most importantly, their chemical and thermal stabilities. Two distinct steps characterize their synthesis a) an alkenylation reaction of a chlorosilane compound with an alkenyl Grignard reagent, and b) a Pt-cata-lyzed hydrosilylation reaction of a peripheral alkenyl moiety with an appropriate hydrosilane species. Scheme 2 shows the synthesis of catalysts Go-1 and Gi-1 via this methodology. In this case, the carbosilane synthesis was followed by the introduction of diamino-bromo-aryl groupings as the precursor for the arylnickel catalysts at the dendrimer periphery. The nickel centers of the so-called NCN-pincer nickel complexes were introduced by multiple oxidative addition reactions with Ni(PPh3)4. 

In a similar approach, naproxen is prepared from an olefin, the product of a Heck reaction (see Section 5.3.2.1). As described above, the reaction proceeds in the presence of water and HC1, additionally copper(n)chloride is added, possibly to prevent the formation of palladium black (Scheme 5.39). Addition of HC1 to the double bond and subsequent oxidative addition reaction of the benzylic chloride with the active Pd° species initiates the catalytic cycle, which proceeds similarly to the ibuprofen synthesis [70-73]. 

Figure 2.20 Synthesis and oxidative addition reactions of Vaska s complex...

---