Electronic effects in the regioselectivity of the singlet oxygen and 4-methyl-1,2,4-triazoline-3,5-dione ene reactions with isobutenylarenes
作者:Mariza N. Alberti、Georgios C. Vougioukalakis、Michael Orfanopoulos
DOI:10.1016/s0040-4039(02)02783-1
日期:2003.1
The regioselectivity of the ene pathway in the photooxidation of several 1-aryl-2-methylpropenes, as probed by stereoselective deuterium-labeling, depends on the electronic nature of the para phenyl-substituents. The reaction of the same array of alkenylarenes with 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) gives ene products with an impressive >97% allylic hydrogen abstraction from the more substituted
Ene Hydroperoxidation of Isobutenylarenes within Dye-Exchanged Zeolite Na−Y: Control of Site Selectivity by Cation−Arene Interactions
作者:Manolis Stratakis、Constantinos Rabalakos、Giannis Mpourmpakis、George E. Froudakis
DOI:10.1021/jo020599g
日期:2003.4.1
The site selectivity in the singlet oxygen ene reaction of several deuterium-labeled isobutenylarenes depends on the position and the electronic nature of the aryl substitutents. For example, 1-(4-trifluoromethylphenyl)-2-methylpropene gives 82% twin selectivity whereas the isomeric 1-(2-trifluoromethylphenyl)-2-methylpropene gives 68% twix selectivity. If photooxygenation of these CF3-substituted compounds is carried out in solution, the opposite selectivity trends are found. On the basis of DFT calculations, these results are rationalized in terms of oxygen-cation and cation-arene interactions.