Abstract
Electrohydrocyclization (EHC) reactions began in the 1960’s with Baizer and Anderson and were eventually applied to mediated EHC reactions by Miranda, Wade, and Little in the early 2000’s. Mediated EHC reactions can lead to further advancements in organic synthesis in regards to conducting diastereoselective reactions. Currently, it is uncertain how exactly Ni(II) salen mediators are involved during EHC reactions. Depending upon the reaction mechanism and how the electron is transferred, the mediator may or may not be able to affect the stereochemistry of the final electrolysis product. For this thesis, multiple bulk electrolysis (BE) reactions were carried out with various mediators. There was much evidence from the cyclic voltammetry experiments that a catalytic electrolysis and an inner sphere electron transfer occurred during the BE reactions. However, there was a solution color change during the BE reactions which was due to the metal being reduced, indicating an outer sphere electron transfer. It appears that a combination of the two mechanisms occurred. The cis/trans ratio results from the mediated BE reactions did not show any clear isomer selection. Each reaction resulted in about the same isomer ratio. The following results were obtained for the mediated BE reactions with the EHC substrate: Ni(II) salen c/t = 1/1.46, 1,2-ethylenediamine Ni(II) di-tert-butyl salen c/t = 1/1.36, 1,2-phenylenediamine Ni(II) di-tert-butyl salen c/t = 1/1.21, (R,R)-1,2-cyclohexanediamine Ni(II) di-tert-butyl salen c/t = 1/1.20, (S,S)-1,2-cyclohexanediamine Ni(II) di-tert-butyl salen c/t = 1/1.34. The bridge variations and the added tert-butyl groups on the mediators did not greatly change the cis/trans results when compared to the BE reaction with Ni(II) salen. The tert-butyl groups were too bulky to allow for the electron transfer and cyclization to occur concertedly on the mediator. This required an inner sphere electron transfer through a covalent linkage. More BE reactions are needed with mediators containing the same bridge variations without the tert-butyl groups.