Alkadienyl cations

Deno, Richey, and their co-workers88 have observed a substantial number of alkadienyl cations. Sorensen239 has observed divinyl and trivinyl cations 83 and 84. 

Alkadienyl cations such as the 1,3,5-trimethylheptadienyl cation 85 show great tendency to cyclize [Eq. (3.37)] and these reactions have been followed by NMR.240 Several novel fulvenes have been protonated to their corresponding dienyl cations241 (e.g., 86 and 87). 

Alkadienyl cations show great tendency to cyclize and these reactions have been followed by NMR80. More recently several novel fulvenes have been protonated to... 

The 3-alkyi-1,3-butadiene-2-carboxylate (2-vinylacrylate) 850 is obtained in a high yield by the carbonylation of the 2-alkyl-2,3-butadienyl carbonate 849 under mild conditions (room temperature, atm)[522]. The corresponding acids are obtained in moderate yields by the carbonylation of 2,3-alkadienyl alcohols under severe conditions (100 °C, 20 atm) using a cationic Pd catalyst and p-TsOH[523],... 

Cycloalkenes can undergo a retro-Diels-Alder reaction (Section 13.11) that produces an alkene and an alkadienyl radical cation ... 

---