Diastereoselective Protonation on Radical Anions of Electron-Deficient Alkenes via Photoinduced Electron Transfer Tomoo Hayamizu Hajime Maeda Kazuhiko Mizuno 10.1021/jo0496953.s007 https://acs.figshare.com/articles/journal_contribution/Diastereoselective_Protonation_on_Radical_Anions_of_Electron_Deficient_Alkenes_via_Photoinduced_Electron_Transfer/3331243 Diastereoselective protonations in the photoinduced electron transfer (PET) reactions of 1,1-dicyanoethene derivatives (<b>1a</b><b>−</b><b>e</b>) by use of organosilicon compounds such as allyltrimethylsilane (<b>2</b>) and benzyltrimethylsilane (<b>5</b>) are described. Irradiation of an acetonitrile−acetic acid solution containing 4-<i>tert</i>-butylcyclohexylidenepropanedinitrile (<b>1a</b>) and an excess of <b>2</b> in the presence of phenanthrene (Phen) as a sensitizer afforded reduction and allylated products (<b>3a</b>, <b>4a</b>) in 63:37 and 57:43 ratios in a less regioselective manner. Photoreactions of 3,3,5-trimethylcyclohexylidenepropanedinitrile (<b>1b</b>), 2-methylcyclohexylidenepropanedinitrile (<b>1c</b>), bicyclo[2.2.1]-2-heptylidenepropanedinitrile (<b>1d</b>), and 1,7,7-trimethylbicyclo[2.2.1]-2-heptylidenepropanedinitrile (<b>1e</b>) with <b>2</b> showed higher diastereoselectivity via the PET process. Similar diastereoselectivities were obtained in the Phen-sensitized photoreaction of <b>1a</b><b>−</b><b>e</b> with <b>5</b>. When 2,4,6-trimethylpyridinium tosylate (<b>7</b>) was used as a proton source in place of acetic acid, the product ratios were substantially changed in several cases. From these results, steric and torsional effects have been postulated as important factors for the control of the diastereoselectivity in these PET reactions. 2004-07-23 00:00:00 PET process regioselective manner torsional effects product ratios acetic acid organosilicon compounds photoinduced electron transfer diastereoselectivity Photoinduced Electron Transfer Diastereoselective protonations allylated products Similar diastereoselectivities PET reactions Radical Anions Diastereoselective Protonation 1 e proton source