95128-48-6Relevant academic research and scientific papers
Selectivity Reverse of Hydrosilylation of Aryl Alkenes Realized by Pyridine N-Oxide with [PSiP] Pincer Cobalt(III) Hydride as Catalyst
Dong, Yanhong,Xie, Shangqing,Zhang, Peng,Fan, Qingqing,Du, Xinyu,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
, p. 4551 - 4562 (2021/04/06)
Six silyl cobalt(III) hydrides 1-6 with [PSiP] pincer ligands having different substituents at the P and Si atoms ([(2-Ph2PC6H4)2MeSiCo(H)(Cl)(PMe3)] (1), [(2-Ph2PC6H4)2HSiCo(H)(Cl)(PMe3)] (2), [(2-Ph2PC6H4)2PhSiCo(H)(Cl)(PMe3)] (3), [(2-iPr2PC6H4)2HSiCo(H)(Cl)(PMe3)] (4), [(2-iPr2PC6H4)2MeSiCo(H)(Cl)(PMe3)] (5), and [(2-iPr2PC6H4)2PhSiCo(H)(Cl)(PMe3)] (6)) were synthesized through the reactions of the ligands (L1-L6) with CoCl(PMe3)3 via Si-H bond cleavage. Compounds 1-6 have catalytic activity for alkene hydrosilylation, and among them, complex 3 is the best catalyst with excellent anti-Markovnikov regioselectivity. A silyl dihydrido cobalt(III) complex 7 from the reaction of 3 with Ph2SiH2 was isolated, and its catalytic activity is equivalent to that of complex 3. Complex 7 and its derivatives 10-12 could also be obtained through the reactions of complexes 3, 1, 4, and 5 with NaBHEt3. The molecular structure of 7 was indirectly verified by the structures of 10-12. To our delight, the addition of pyridine N-oxide reversed the selectivity of the reaction, from anti-Markovnikov to Markovnikov addition. At the same time, the reaction temperature was reduced from 70 to 30 °C on the premise of high yield and excellent selectivity. However, this catalytic system is only applicable to aromatic alkenes. On the basis of the experimental information, two reaction mechanisms are proposed. The molecular structures of cobalt(III) complexes 3-6 and 10-12 were determined by single crystal X-ray diffraction analysis.
General and practical one-pot synthesis of dihydrobenzosiloles from styrenes
Kuznetsov, Alexey,Gevorgyan, Vladimir
supporting information; experimental part, p. 914 - 917 (2012/05/05)
A one-pot synthesis of dihydrobenzosiloles from styrenes has been developed. The reaction involves the nickel-catalyzed hydrosilylation of styrene with diphenylsilane, followed by the iridium-catalyzed dehydrogenative cyclization. This method is efficient for both electron-rich and -deficient styrenes and exhibits good functional group tolerance, as well as excellent regioselectivity. The forming dihydrobenzosiloles can be efficiently converted into valuable benzosiloles or 2-hydroxyphenethyl alcohols.
