Pericyclic reactions writing mechanisms

Another reason why it is sometimes difficult to identify conclusively whether a reaction proceeds by a pericyclic mechanism is that it is usually possible to write very reasonable alternative free-radical or polar mechanisms for the same reaction. In this text, when both pericyclic and nonpericyclic mechanisms can be drawn for a reaction, the pericyclic mechanism will be assumed to be correct unless there is theoretical or experimental evidence to the contrary. 

The following reaction is known as the Carroll rearrangement. Write a mechanism for this reaction. What pericyclic reaction is involved ... 

At first glance, the following reaction appears to be a [2-1-2] cycloaddition of a single double bond from cyclopen tad iene with the C=C double bond of diphenylketene. However, it has been experimentally shown that the product actually results from two more conventional pericyclic reactions. Show by writing an alternative mechanism what these two reactions must be. 

Write reasonable mechanisms for the following multistep pericyclic reactions based on Evans principle ... 

An aryne-ene reaction has been reported and evidence supports it as a pericyclic reaction [59], Write a mechanism for the reaction below. When the allylic methyl groups are substituted with deuterium, greater than 95% deuterium transfer is observed. How does this support the conclusion that the reaction is conceited ... 

---

See also in sourсe #XX -- [ , , , , , ]

---