Hydrometallation rearrangement

The other questions raised above—about the relative roles of alkene complexation and hydrometallation, and the possible requirement for structural rearrangement before insertion—cannot be answered in this system, as the alkene binding and geometry are essentially immutable. Roe has shown for a rhodium complex with trans alkene and hydride ligands, that rearrangement does not contribute to the hydrometallation barrier the first step in equation (10) is fast, and k2 is rate determining. It is notable that for... 

The RhI-catalysed rearrangement of A-allylaziridines to (Z)-A-alkenylaziridines has been investigated by computational methods and the reaction occurs via a hydrometalation//3-hydride elimination. Alkylidene cycloheptadienes have been prepared via a rhodium(I)-catalysed tandem isomerization of cyclopropylenynes through a [1,5] carbon-carbon migration via an allene intermediate with high Z E selectivities (Scheme 152). ... 

The ability of Pd to participate in both hydrometallation and dehydrometallation snggests that Pd and its complexes can serve as catalysts for isomerization of alkenes and alkynes via a series of hydropalladation-dehydropalladation, that is 1,2-H shift. On the other hand, Pd-induced aUylic rearrangement provides a mechanism whereby alkenes can iso-merize via 1,3-shift. In either of these processes, the crucial reqnirement is the presence or ready availability of an empty coordination site. As amply demonstrated throughout this Handbook, Pd is imminently capable of serving as the catalyst center for isomerization of alkenes and alkynes. 

Vinylallenes can be hydrometallated to produce 1-cobaloxime-substituted dienyl complexes (Equation (25)). Cobaloxime-substitued 1,3-diene without a substituent in the 3-position will participate in thermal and Lewis acid-catalyzed Diels-Alder reactions, but the resulting cycloadducts apparently rearrange and give products with... 

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