Reference of (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diolOn October 18, 2004 ,《Synthesis and characterization of alkyllanthanum biphenolate complexes as catalysts for hydroamination/cyclization and hydrosilylation》 was published in European Journal of Inorganic Chemistry. The article was written by Gribkov, Denis V.; Hampel, Frank; Hultzsch, Kai C.. The article contains the following contents:
The homochiral, dimeric biphenolate alkyllanthanum complex [La{(R)-Biphen}{CH(SiMe3)2}]2 can be prepared by facile alkane elimination starting from [La{CH(SiMe3)2}3] and enantiopure (R)-3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphenyl-2,2′-diol [H2{(R)-Biphen}]. Single-crystal x-ray diffraction revealed that the two La{(R)-Biphen}{CH(SiMe3)2} fragments are connected through bridging phenolate groups of the biphenolate ligands. The two different phenolate groups undergo an intramol. exchange process in solution leading to their equivalence on the NMR time scale. The biphenolate alkyl complex shows high catalytic activity for hydroamination/cyclization of aminoalkenes, similar to previously known lanthanocene catalysts, but only low enantio-selectivity. Addition of THF to [La{(R)-Biphen}{CH(SiMe3)2}]2 leads to a monomeric tris-THF adduct [La{(R)-Biphen}{CH(SiMe3)2}(THF)3] with higher catalytic activity than the THF-free homochiral dimer in the cyclization of 2,2-dimethylpent-4-enylamine, suggesting that the dimeric structure of the catalyst system prevails under catalytic conditions in the absence of THF. Addition of HN(SiHMe2)2 to [La{(R)-Biphen}{CH(SiMe3)2}(THF)3] results in the formation of [La{(R)-Biphen}{N(SiHMe2)2}(THF)3] which is in equilibrium with its homochiral dimer [La{(R)-Biphen}{N(SiHMe2)2}(THF)]2 at elevated temperatures The biphenolate alkyl complexes exhibit good catalytic activity and diastereoselectivity in the hydrosilylation of styrene. Hydrosilylation of 1-hexene and norbornene also proceeds with high diastereoselectivity but rather low activity. In the part of experimental materials, we found many familiar compounds, such as (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol(cas: 329735-68-4Reference of (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol)
(R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol(cas: 329735-68-4) belongs to phenols. Phenols are more acidic than typical alcohols.Reference of (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol The acidity of the hydroxyl group in phenols is commonly intermediate between that of aliphatic alcohols and carboxylic acids (their pKa is usually between 10 and 12).
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