Pyrrolidine → 2-(Propan-2-yl)-5-(propan-2-ylidene)cyclopenta-1,3-diene

Participants

Reaction Steps

Therefore, 1,3-diisopropylcyclopentadiene was selected as the starting point for the synthesis. Unfortunately, the reported syntheses of 1,3-diisopropylcyclopentadiene gave low yields since the final step was always separation of the 1,3 product from the 1,2 product. A more selective method was found by extension of work by Nile in which he prepared a number of 1,3 disubstituted cyclopentadienes using a fulvene route. Using this method, reaction of isopropylcyclopentadiene with acetone catalyzed by pyrrolidine gave the 3-isopropyl-6,6-dimethylfulvene. Subsequent reduction of the fulvene with LAH and hydrolysis provided 1,3-diisopropylcyclopentadiene, "iPr2Cp." ##STR10##

Provenance & Evidence