33968-47-7Relevant academic research and scientific papers
Cooperative Activation of Cobalt–Salen Complexes for Epoxide Hydration Promoted on Flexible Porous Organic Frameworks
Zhong, Mingmei,Li, He,Chen, Jian,Tao, Lin,Li, Can,Yang, Qihua
supporting information, p. 11504 - 11508 (2017/08/30)
Developing solid catalysts with multiple active sites working cooperatively is desirable for efficient chemical transformations. However, most solid catalysts are rigid and impede the cooperation between their spatially isolated active sites. Two flexible porous organic frameworks (POFs) with integrated Co(salen) as active sites have been successfully synthesized for mimicking the cooperative modes of enzymes. The POFs exhibit second-order rate dependence on Co(salen) concentration in the network and afford much higher TOF (3300 versus 2670 h?1) than the homogeneous counterpart in the hydration of propylene epoxide. POFs with a flexible network thus not only facilitate but also enhance the cooperation of nearby Co(salen). Moreover, POFs could catalyze oversized substrates, have a wide substrate scope, and exhibit high stability.
Osmium(III) and osmium(V) complexes bearing a macrocyclic ligand: A simple and efficient catalytic system for cis-dihydroxylation of alkenes with hydrogen peroxide
Sugimoto, Hideki,Ashikari, Kenji,Itoh, Shinobu
, p. 2154 - 2160 (2013/09/23)
A simple protocol that uses [OsIII(OH)(H2O)(L-N 4Me2)](PF6)2 (1; L-N 4Me2=N,N′-dimethyl-2,11-diaza[3.3](2,6) pyridinophane) as a catalyst and H2O2 as a terminal oxidant for efficient cis-1,2-dihydroxylation of alkenes is presented. Unfunctionalized (or aliphatic) alkenes and alkenes/styrenes containing electron-withdrawing groups are selectively oxidized to the corresponding vicinal diols in good to excellent yields (46-99 %). In the catalytic reactions, the stoichiometry of alkene:H2O2 is 1:1, and thus the oxidant efficiency is very high. For the dihydroxylation of cyclohexene, the catalytic amount of 1 can be reduced to 0.01 mol % to achieve a very high turnover number of 5500. The active oxidant is identified as the Os V(O)(OH) species (2), which is formed via the hydroperoxide adduct, an OsIII(OOH) species. The active oxidant 2 is successfully isolated and crystallographically characterized. The wizard of Os: A simple protocol that uses [OsIII(OH)(H2O)(L-N4Me 2)](PF6)2 (1) and H2O2 for efficient cis-1,2-dihydroxylation of alkenes is presented. Unfunctionalized (or aliphatic) alkenes and alkenes/styrenes containing electron-withdrawing groups were converted into the corresponding vicinal diols in good to excellent yields. It has been confirmed that the OsV(O)(OH) species (2) is the active oxidant, which is formed via the hydroperoxide adduct A. Copyright
