51229-55-1Relevant academic research and scientific papers
Photoredox/Nickel Dual Catalytic Cross-Coupling of Potassium Thiomethyltrifluoroborates with Aryl and Heteroaryl Bromides
Townsend, Katherine,Huestis, Malcolm P.,Tellis, John C.
, p. 6937 - 6942 (2021/05/29)
The cross-coupling of S-aryl and S-alkyl potassium thiomethyltrifluoroborates with aryl and heteroaryl bromides is reported via photoredox/nickel dual catalysis. The transformation is achieved under mild conditions with commercially available or readily prepared, air stable reagents and affords benzylthioether products in moderate to good yields with good functional group tolerance. A practical and improved synthesis of potassium thiomethyltrifluoroborates is also reported that affords access to previously undescribed reagents.
Radical Cleavage and Competing Photoreactions of Phenacyl Sulfides
Wagner, Peter J.,Lindstrom, Michael J.
, p. 3062 - 3067 (2007/10/02)
The photochemistry of ketones with the stuctures PhCOCH2SR, PhCOCH2S(O)R, PhCOCH2SO2R, and p-X-PhCOCH2SPh has been studied.They all give primarily acetophenone as product when irradiated in the presence of benzenethiol, which traps free phenacyl radicals formed by excited state β-cleavage.The sulfur-centered radicals give coupling products.The maximum quantum yield for β-cleavage is 0.40; apparently 60percent of the initially formed radical pairs undergo in-cage reaction.When R = methyl or butyl, some acetophenone is formed by γ-hydrogen abstraction as well.Alkyl subtituents on the α-carbon enhance the disproportionation reactions of the phenacyl radicals.Measurements of quantum yields and triplet life times (by Stern-Volmer quenching of acetophenone formation) allowed determination of rate constants for β-cleavage as follows: PhS, 1E10-1E11; MeS(O), 6 * 1E9; BuS, 1.5 * 1E8; BuSO2, 1 * 1E7 s-1.Ring substituents increase triplet lifetimes.Absorption and phosphorescence spectra indicate that the n,?* and ?,?* transitions both involve some population of the C-S ?* orbital.This mixing, together with free spin density on the excited carbonyl carbon, appears to determine the rate constant for cleavage.Radical cleavage is also very fast and efficient for p-((phenylthio)methyl)acetophenone.
