This work discloses a palladium-catalyzed borylation
of the B–I
bond of carboranes with B 2 pin 2 . A series of
9-Bpin- o -carborane and 9-Bpin- m -carborane
derivatives have been synthesized with moderate to good yields. This
work has important references for functionalization of the B–I
bond of carboranes.
Hydrogen has attracted much attention as one of the most promising chemical fuel candidates because of its zero emission during consumption. In order to solve the freezing problem of water based hydrolysis process, herein, the Pd/C as an efficient and stable catalyst for the methanolysis, ethanolysis, propanolysis and butanolysis of B 2 pin 2 for the generation of hydrogen has been first developed. The large kinetic isotope effect (KIE) of k H /k D = 5.0, D 2 formation from CD 3 OD and in situ tandem reaction have confirmed that alcohol is the only hydrogen source. Interestingly, the order of E a of these alcohols in H 2 evolution is MeOH (methanol, 29.57 kJ/mol) < EtOH (ethanol, 34.80 kJ/mol) < PrOH (propanol, 39.08 kJ/mol) < n BuOH (n-butanol, 41.98 kJ/mol), which is consistent with the known order of acidities of these alcohols (MeOH > EtOH > PrOH > n BuOH).
Ming Huang,Changsheng Zhou,Ke-Fang Yang,Ze Li,Guo-Qiao Lai,Pinglu Zhang
An effective (NHC)AgCl catalysis was developed in the hydroborylation of cyclopropenes with B2pin2, delivering a variety of cyclopylboronates in a stereoselective manner, which could be easily transformed for the construction of versatile cyclopropanes. This protocol works effectively under mild reaction conditions in an open-air atmosphere, and it was easy to apply on a gram scale. This novel method in detail was also explored by control experiments, providing a number of key insights. The kinetic process followed by 1H NMR indicated that the reaction was finished in 15 min. Furthermore, the mechanism of silver(I)-catalyzed hydroborylation of cyclopropenes was proposed, with the protonation by methanol as the rate-determining step.
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