Organopalladium Stille reactions

Eberson has compared the isomer ratios for the acetoxylation of aromatic substrates at the anode with those obtained from different oxidants (Table 1) [26]. The anodic reaction proceeds by an initial electron transfer, thus forming a radical cation, which is then attacked by acetate ion. The homogeneous reactions, which come closest to the results of the anodic oxidation, are the Co(III)Wi2O40 and the Ag(II) oxidation. These and also the Ce(IV) oxidant, which still exhibits some similarities in the isomer distribution, have been characterized as electron transfer oxidants, whereas the Pd(II)-catalyzed acetoxylation has been shown to proceed via organopalladium species [27]. The isomer distributions in the latter, where predominantly meta orientation is being observed, are drastically different from those of ET-mediated reactions. 

This reaction involves organoboronic acids [RB(OH)2] and could be included in chapter 5 with organo-borane chemistry. The chemistry is sufficiently different from that presented in Chapter 5, and involves organopalladium catalysts so it is presented with the Heck reaction and Stille coupling. This assumption is reasonable since it may be a synthetic alternative to those reactions.267... 

In principle, there can be many other Pd-catalyzed rearrangement reactions. At present, however, the overall scope of Pd-catalyzed rearrangement reactions is still rather limited. In one sense, lack of skeletal rearrangements in some Pd-catalyzed reactions, such as Wacker processes, where cationic species may be implicated as transient species, is considered to be a very desirable feature of organopalladium chemistry. On the other... 

The existence of organopalladium(iv) complexes, in particular triorganopalladium(iv) species, has been invoked as intermediates in carbon-carbon bond-formation reactions involving dimethyldiphosphinepalladium(ii) compounds and iodomethane by Milstein and Stille as early as 1979." ... 

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