60664-80-4Relevant academic research and scientific papers
Dirhodium-Catalyzed Enantioselective B?H Bond Insertion of gem-Diaryl Carbenes: Efficient Access to gem-Diarylmethine Boranes
Huang, Ming-Yao,Li, Xiao-Yu,Su, Yu-Xuan,Yang, Liang-Liang,Zhao, Yu-Tao,Zhu, Shou-Fei
supporting information, p. 24214 - 24219 (2021/10/07)
The scarcity of reliable methods for synthesizing chiral gem-diarylmethine borons limits their applications. Herein, we report a method for highly enantioselective dirhodium-catalyzed B?H bond insertion reactions with diaryl diazomethanes as carbene precursors. These reactions afforded chiral gem-diarylmethine borane compounds in high yield (up to 99 % yield), high activity (turnover numbers up to 14 300), high enantioselectivity (up to 99 % ee) and showed unprecedented broad functional group tolerance. The borane compounds synthesized by this method could be efficiently transformed into diaryl methanol, diaryl methyl amine, and triaryl methane derivatives with good stereospecificity. Mechanistic studies suggested that the borane adduct coordinated to the rhodium catalyst and thus interfered with decomposition of the diazomethane, and that insertion of a rhodium carbene (generated from the diaryl diazomethane) into the B?H bond was most likely the rate-determining step.
Enantioselective Si-H Insertion Reactions of Diarylcarbenes for the Synthesis of Silicon-Stereogenic Silanes
Jagannathan, Jake R.,Fettinger, James C.,Shaw, Jared T.,Franz, Annaliese K.
supporting information, p. 11674 - 11679 (2020/07/27)
We report the first example of enantioselective, intermolecular diarylcarbene insertion into Si-H bonds for the synthesis of silicon-stereogenic silanes. Dirhodium(II) carboxylates catalyze an Si-H insertion using carbenes derived from diazo compounds where selective formation of an enantioenriched silicon center is achieved using prochiral silanes. Fourteen prochiral silanes were evaluated with symmetrical and prochiral diazo reactants to produce a total of 25 novel silanes. Adding an ortho substituent on one phenyl ring of a prochiral diazo enhances enantioselectivity up to 95:5 er with yields up to 98percent. Using in situ IR spectroscopy, the impact of the off-cycle azine formation is supported based on the structural dependence for relative rates of diazo decomposition. A catalytic cycle is proposed with Si-H insertion as the rate-determining step, supported by kinetic isotope experiments. Transformations of an enantioenriched silane derived from this method, including selective synthesis of a novel sila-indane, are demonstrated.
Contributions of Quantum Mechanical Tunneling to the Rate of Benzylic Hydrogen Atom Abstractions Reactions of Triplet Diarylcarbenes in Fluid Solution
Shaffer, Myron W.,Leyva, Elisa,Soundararajan, N.,Chang, Edith,Chang, David H. S.,et al.
, p. 7273 - 7277 (2007/10/02)
Kinetic isotope effects for the benzylic hydrogen atom abstraction reactions of the triplet states of several diarylcarbenes with toluene-toluene-d8 in fluid solution were determined by measuring the ratio of 1,2-diphenylethane to 1,2-diphenylethane-d7 pr
