Aryl iodides chloride dimer

As mentioned before (Sect. 4.4) the stoichiometric reaction of phenyinorbornylpalladium chloride dimer with an aryl iodide in the absence of added norbornene gave hexahydromethanotriphenylene [43] (Scheme 4). When the same reaction was carried out in the presence of norbornene, the product derived from incorporation of another arene molecule was obtained (Scheme 6). This result could be explained as a consequence of the ortho effect. [7,25c, 47]. 

As conclusion, the high catalytic efficiency of the polymeric palladacycle derived from Kaiser oxime resin similar to that of related unsupported dimeric pal-ladacycles was observed in the Mizoroki-Heck reaction. This polymer showed a good catalytic activity, not only in organic but also in aqueous media, for aryl iodides, bromides, and activated chlorides with high turnover numbers (TONs), rmder aerobic conditions at relatively lower temperature. 

Condensations of amines with 1-chlorocycloheptene in the presence of the complex base , sodamide and sodium t-butoxide, gave mixtures of enamines and cyclo-hepta-1,2-diene dimer. Excess n-butyl-lithium has been used to convert vinyl and aryl bromides into organolithium compounds which undergo useful reactions with, for example, benzophenone, dimethyl disulphide, diphenyl disulphide, trimethylsilyl chloride, and methyl iodide. Hence 1-bromo-cis-cyclononene was converted into 1-methylthio-cis-cyclononene via 1-lithio-cis-cyclononene the 1-methylthio... 

Furthermore, homobimetallic dimers derived from phosphinous acids [134] or phosphine chlorides [239], palladium nanoparticles stabilized by wBu4NBr [142], as well as the catalyst derived from [Pd(C3H5)Cl]2 as well as the tetraphosphine ligand Tedicyp (l,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane) [240] are also systems with high catalytic activity that enable the cross-coupling of primary alkylzincs and aryl bromides or iodides with good generality. 

Ultrasound can give useful improvements in the yield, reaction time, and convenience of organometallic reactions, and these facets of the technique are demonstrated well in its application to the Reformatsky reaction. Yields are improved by up to almost 100 % over the conventional method, and are nerally superior even to those of the trimethyl borate method. Reaction times are reduced by a factor of 5-10, and the need to prepare zinc powder by the active-metal reduction of anhydrous zinc chloride is eliminated. This technique has also been applied to the zinc-mediated dimerization of a,a -dibromo -xylene, although only low yields are obtained, and to the Pd-catalysed zinc coupling of allyl or aryl halides with perfluoroalkyl iodides. ... 

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