157731-58-3Relevant academic research and scientific papers
NMR Quantification of Hydrogen-Bond-Activating Effects for Organocatalysts including Boronic Acids
Diemoz, Kayla M.,Franz, Annaliese K.
, p. 1126 - 1138 (2019)
The hydrogen-bonding activation for 66 organocatalysts has been quantified using a 31P NMR binding experiment with triethylphosphine oxide (TEPO). Diverse structural classes, including phenols, diols, silanols, carboxylic acids, boronic acids, and phosphoric acids, were examined with a variety of steric and electronic modifications to understand how the structure and secondary effects contribute to hydrogen-bonding ability and catalysis. Hammett plots demonstrate high correlation for the Δδ 31P NMR shift to Hammett parameters, establishing the ability of TEPO binding to predict electronic trends. Upon correlation to catalytic activity in a Friedel-Crafts addition reaction, data demonstrate that 31P NMR shifts correlate to catalytic activity better than pKa values. Boronic acids were investigated, and 31P NMR binding experiments predicted strong hydrogen-bonding ability, for which catalytic activity was confirmed, resulting in the greatest rate enhancement observed in the Friedel-Crafts addition of all organocatalysts studied. A detailed investigation supports that boronic acid activation proceeds through hydrogen-bonding interactions and not coordination with the Lewis acidic boron center. Using 31P NMR spectroscopy offers a simple and rapid tool to quantify and predict hydrogen-bonding abilities for the design and applications of new organocatalysts and supramolecular synthons.
Insight into Copper Catalysis: In Situ Formed Nano Cu2O in Suzuki-Miyaura Cross-Coupling of Aryl/Indolyl Boronates
Ranjani, Ganapathy,Nagarajan, Rajagopal
supporting information, p. 3974 - 3977 (2017/08/14)
A ligand-free copper catalyzed Suzuki-Miyaura coupling of 3,5-diiodopyridine with aryl and indole boronates has been explored in good to excellent yields. In situ generation of nano-Cu2O from CuCl2 under the reaction conditions has been discovered for the first time. The generality of the reaction was further demonstrated by the arylation of 5-iodopyrimidine, iodopyridines, iodobenzenes, and diiodobenzenes and resulted in good to moderate yields. Moreover, bisindole alkaloid Scalaridine A has been successfully synthesized in 60% overall yield.
Selective cine substitution of 1-arylethenyl acetates with arylboron reagents and a diene/rhodium catalyst
Yu, Jung-Yi,Shimizu, Ryosuke,Kuwano, Ryoichi
supporting information; experimental part, p. 6396 - 6399 (2010/11/17)
When the crowd says Bo: A carbon-carbon bond is selectively formed at the β position of 1- arylethenyl acetate when the alkenyl substrate is reacted with arylboronic acids in the presence of a cycloocta-1,5-diene/rhodium catalyst. The choice of the ligand is crucial for the unusual cine substitution. Copyright
