Cascade electrocyclic ring opening

The cascade rearrangements following double addition of alkenyl anions to the squarate ester was initiated by Paquette from the clue of Asensio s finding that twofold addition of organolithium (MeLi, PhLi, etc.) leads to the facile electrocyclic ring opening to 1,4-diketones [102]. This expedient method for construction of complex polycycles is achieved by a simple one-pot process... 

The focus of this chapter has so far not been so much on synthesis, but one very nice cascade reaction to dendralenes incorporating DTF donor groups and dicyanomethylene acceptor groups deserves mention. While TCNE can undergo a thermal [2+2] cycloaddition with electron-rich alkynes followed by electrocyclic ring opening [21, 39], TTF can undergo a similar reaction with electron-poor alkynes [40]. These observations were employed to construct a... 

There is a large literature that describes the electrocyclic ring opening of cyclobutenes and benzocyclobutenes as one step in a cascade of reactions that lead to fused aromatic rings. An example of this class of reactions is Suzuki and... 

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