TY - DATA T1 - Self-Assembled Benzophenone Bis-urea Macrocycles Facilitate Selective Oxidations by Singlet Oxygen PY - 2016/02/19 AU - Michael F. Geer AU - Michael D. Walla AU - Kyril M. Solntsev AU - Cristian A. Strassert AU - Linda S. Shimizu UR - https://acs.figshare.com/articles/dataset/Self_Assembled_Benzophenone_Bis_urea_Macrocycles_Facilitate_Selective_Oxidations_by_Singlet_Oxygen/2407855 DO - 10.1021/jo400685u.s002 L4 - https://ndownloader.figshare.com/files/4047559 KW - oxidation processes KW - methyl KW - allylic alcohol KW - parent benzophenone KW - selectivity KW - UV irradiation KW - cumene KW - form endoperoxides KW - formation KW - columnar host KW - Subsequent UV irradiation KW - Singlet OxygenThis manuscript KW - photophysical properties KW - reactive singlet oxygen KW - triplet sensitizer KW - singlet oxygen KW - oxygenated solvents KW - benzophenone result KW - complex KW - singlet oxygen photoproduction KW - guest molecules N2 - This manuscript investigates how incorporation of benzophenone, a well-known triplet sensitizer, within a bis-urea macrocycle, which self-assembles into a columnar host, influences its photophysical properties and affects the reactivity of bound guest molecules. We further report the generation of a remarkably stable organic radical. As expected, UV irradiation of the host suspended in oxygenated solvents efficiently generates singlet oxygen similar to the parent benzophenone. In addition, this host can bind guests such as 2-methyl-2-butene and cumene to form stable solid host–guest complexes. Subsequent UV irradiation of these complexes facilitated the selective oxidation of 2-methyl-2-butene into the allylic alcohol, 3-methyl-2-buten-1-ol, at 90% selectivity as well as the selective reaction of cumene to the tertiary alcohol, α,α′-dimethyl benzyl alcohol, at 63% selectivity. However, these products usually arise through radical pathways and are not observed in the presence of benzophenone in solution. In contrast, typical reactions with benzophenone result in the formation of the reactive singlet oxygen that reacts with alkenes to form endoperoxides, diooxetanes, or hydroperoxides, which are not observed in our system. Our results suggest that the confinement, the formation of a stable radical species, and the singlet oxygen photoproduction are responsible for the selective oxidation processes. A greater understanding of the mechanism of this selective oxidation could lead to development of greener oxidants. ER -