Nonconjugated dienes rearrangement

Nonconjugated dienes are rearranged to iron carbonyl complexes of conjugated dienes when treated with FefCOjs or Fe3(CO)i2. Thus 1,4-pentadiene gives tmw -l,3-pentadieneiron tricarbonyl (34) possibly by the route ... 

Vinylation of heteroaryl triflates also possible. Vinyl halides can be coupled to alkenes to form dienes. " The reaction of dihydrofurans with vinyl triilates and a palladium catalyst leads to a nonconjugated diene, 33. This example illustrates that the product is formed by an elimination step, as with the Heck reaction (13-10), and double bond migration can occur resulting in allylic rearrangement. 

Nonconjugated dienes bound to electrophilic transition-metal centers are activated toward nucleophilic attack analogous to olefin activation by transition metals discussed in 5.8.2.3.4. Although secondary reactions or rearrangements can occur, the pattern of the nucleophilic addition step (Nuc = nucleophile) leading to a, n complexes is shown... 

Di-7i-methane rearrangements of acyclic and monocyclic 1,4-dienes usually occur in the singlet excited state and, therefore, the reaction takes place on direct irradiation. This is an important limitation since nonconjugated alkenes absorb below 250 nm. Consequently, the DPM reaction in acyclic and monocyclic dienes is restricted to compounds in... 

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