The electrocyclic ring closure of 1,2,4-pentatriene, or vinylallene, is not a synthtically viable transformation, as it is both high energy and reversible.  Delas, Urabe and Sato demonstrated (J. Am. Chem. Soc. 2001 , 123, 7937) an organometallic analog that gives reasonable yield at low temperatures.  Our intial examination of this proecess using denstity functional theory suggests that this is not a simple pericyclic reaction, but rather a cationic process.  Loss of a ligand from the titanium opens up a coordination site that then brings together together the two ends of the carbon framework.  Cyclization through a transition state resembling a titanocycle proceeds much more readily than the parent hydrocarbon ring closure.  Our ongoing examination seeks to clarify this mechanism and also goes on to look at the effect of substituents and stereochemical considerations.

Examination of the cyclization mechanism for titanated vinylallenes

243rd National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.