Manganese—lead bonds reactions with

Reactions with alkynes may lead to the formation of cyclized products. The reaction of iodobenzenes with two equivalents of an alkyne has been shown to give naphthalene derivatives in the presence of cobalt catalyst with a manganese reduc-tant. The process, shown in Scheme 15, is thought to involve oxidative addition of the aryliodide to cobalt followed by double alkyne insertion. The cobalt-catalysed annulation step probably involves an pathway. The cyclopentadienyl-rhodium-catalysed annulation of benzoic acids with alkynes has been used to form isocoumarin derivatives, such as (126). The process is thought to involve cyclorhodation at the ortho-position of a rhodium benzoate intermediate, followed by alkyne insertion to form a seven-membered rhodacycle and reductive elimination The silver-catalysed annulations of diphenylphosphine oxides with alkynes proceed in the absence of rhodium. Benzophosphole oxides such as (127), formed with diphenylethyne, are produced. Here, the proposed mechanism involves homolytic cleavage of the phosphorus-hydrogen bond to give a radical which can add to the alkyne and subsequently cyclize. ... 

Both oxides of silver, Ag20 and AgO, have been used for aldehyde oxidations. The silver]I) reagent has mainly been applied in transformations of aliphatic [83] and aromatic aldehydes [84], less so in oxidations of organometallic complexes bearing an aldehyde function [85] or a,P-unsaturated compounds [86]. Use of the silver(II) oxide is less common [70, 87], probably due to its limited availability and high cost Cyanide ions catalyze this oxidation in methanol leading to carboxylic acids (and not to esters as compared with manganese) [70]. In reactions with a,p-unsaturated aldehydes, double bond isomerizations have been observed [70]. Less common silver re-... 

A hydroxy and an arylthio group can be added to a double bond by treatment with an aryl disulfide and lead tetraacetate in the presence of trifluoroacetic acid." Manganese and copper acetates have been used instead of Pb(OAc)4. ° Addition of the groups OH and RSO has been achieved by treatment of alkenes with O2 and a thiol (RSH)." Two RS groups were added, to give vie- dithiols, by treatment of the alkene with a disulfide RSSR and Bp3-etherate."° This reaction has been carried... 

The liquid polymer is converted to the rubbery state by reagents that react with mercaptan (-SH) and side groups of the polymer segments by oxidation, addition or condensation to effect sulfide (-S-S-) bond formation. The oxidation reactions are exothermic and accelerated by an alkaline environment. The most commonly employed oxidizing agents which are suitable for curing liquid polymers are cobalt or manganese or lead octoate, p-quinonedioxime and di- or tri-nitrobenzene. Epoxy resin also reacts with liquid polysulfide polymers by addition in the presence of an aliphatic or aromatic amine and polyamide activator as shown in Equation 5.8 ... 

Another oxidation reactions have been reported that led to C-C bond formation. They deal with treatment of A-allylsilane-substituted SMAs with CAN, lead tetraacetate or manganese triacetate to form methylene piperidines and azepines. Yields are in the same range as those obtained using SET-photolytic or electrolytic processes.359... 

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