Posts Tagged ‘asynchronous’

The direct approach is not always the best: butadiene plus dichlorocarbene

Wednesday, September 19th, 2012

The four-electron thermal cycloaddition (in reverse a cheletropic elimination) of dichlorocarbene to ethene is a classic example of a forbidden pericyclic process taking a roundabout route to avoid directly violating the Woodward-Hoffmann rules. However, a thermal six-electron process normally does take the direct route, as in for example the Diels-Alder cycloaddition as Houk and co have recently showed using molecular dynamics[1]. So can one contrive a six-electron cycloaddition involving dichlorocarbene?



  1. K. Black, P. Liu, L. Xu, C. Doubleday, and K.N. Houk, "Dynamics, transition states, and timing of bond formation in Diels-Alder reactions", Proceedings of the National Academy of Sciences, vol. 109, pp. 12860-12865, 2012.