TY  - JOUR
A1  - Fudickar, Werner
A1  - Metz, Melanie
A1  - Mai-Linde, Yasemin
A1  - Krüger, Tobias
A1  - Kelling, Alexandra
A1  - Sperlich, Eric
A1  - Linker, Torsten
T1  - Influence of functional groups on the ene reaction of singlet oxygen with 1,4-cyclohexadienes
T2  - Photochemistry and photobiology : the official journal of the American Society for Photobiology
N2  - The photooxygenation of 1,4-cyclohexadienes has been studied with a special focus on regio- and stereoselectivities. In all examples, only the methyl-substituted double bond undergoes an ene reaction with singlet oxygen, to afford hydroperoxides in moderate to good yields. We explain the high regioselectivities by a "large-group effect" of the adjacent quaternary stereocenter. Nitriles decrease the reactivity of singlet oxygen, presumably by quenching, but can stabilize proposed per-epoxide intermediates by polar interactions resulting in different stereoselectivities. Spiro lactams and lactones show an interesting effect on regio- and stereoselectivities of the ene reactions. Thus, singlet oxygen attacks the double bond preferentially anti to the carbonyl group, affording only one regioisomeric hydroperoxide. If the reaction occurs from the opposite face, the other regioisomer is exclusively formed by severe electrostatic repulsion in a perepoxide intermediate. We explain this unusual behavior by the fixed geometry of spiro compounds and call it a "spiro effect" in singlet oxygen ene reactions.
Y1  - 2021
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/57186
SN  - 0031-8655
SN  - 1751-1097
VL  - 97
IS  - 6
SP  - 1289
EP  - 1297
PB  - Wiley
CY  - Malden, Mass.
ER  -