Enantioselective Protonation of Radical Anion Intermediates in Photoallylation and Photoreduction Reactions of 3,3-Diaryl-1,1-dicyano-2-methylprop-1-ene with Allyltrimethylsilane

• Published in: Molecules (Basel, Switzerland) Vol. 24; no. 14; p. 2677
• Main Authors: Maeda, Hajime, Iida, Masayuki, Ogawa, Daisuke, Mizuno, Kazuhiko
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 23.07.2019; MDPI
• Subjects: Acetic acid; Acetic Acid - chemistry; Acetonitrile; Acids; Alkenes - chemistry; allylsilane; Anions; Carboxylic acids; Carboxylic Acids - chemistry; Catalysis; Catalysts; Effluents; electron deficient alkene; Electron transfer; enantiomer; Enantiomers; enantioselectivity; Felkin-Anh model; Free Radicals; Hydrogenation; Intermediates; Light; mandelic acid; Nitriles - chemistry; Phenanthrene; Phenanthrenes - chemistry; Photochemical Processes; Photochemical reactions; photoinduced electron transfer; photoreaction; Photoredox catalysis; photoredox catalyst; Photoreduction; Protonation; Protons; radical anion; Stereoisomerism; Trimethylsilyl Compounds - chemistry; enantioselectivity; Felkin-Anh model; electron deficient alkene; enantiomer; radical anion; mandelic acid; photoinduced electron transfer; photoredox catalyst; photoreaction; allylsilane
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules24142677

Photoreactions of acetonitrile solutions of 3,3-diaryl-1,1-dicyano-2-methylprop-1-enes ( - ) with allyltrimethylsilane ( ) in the presence of phenanthrene as a photoredox catalyst and acetic acid as a proton source formed photoallylation ( ) and photoreduction ( ) products via photoinduced electron transfer pathways. When ( )-mandelic acid was used as the proton source, the reactions proceeded with 3.4 and 4.8 %ee for formation of and , respectively. The results of studies of the effect of aryl ring substituents and several chiral carboxylic acids suggested that the enantioselectivities of the reactions are governed by steric controlled proton transfer in intermediate complexes formed by π-π and OH-π interactions of anion radicals derived from - and chiral carboxylic acids.