Recommanded Product: (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diolOn October 6, 2003 ,《Synthesis and characterization of new biphenolate and binaphtholate rare-earth-metal amido complexes: Catalysts for asymmetric olefin hydroamination/cyclization》 was published in Chemistry – A European Journal. The article was written by Gribkov, Denis V.; Hultzsch, Kai C.; Hampel, Frank. The article contains the following contents:
Monomeric diolate amido yttrium complexes [Y{diolate}{N(SiHMe2)2}(THF)2] can be prepared in good yield by treating [Y{N(SiHMe2)2}3(THF)2] with either 3,3′-di-tert-butyl-5,5′,6,6′-tetramethyl-1,1′-biphenyl-2,2′-diol (H2(Biphen)), 3,3′-bis(2,4,6-triisopropylphenyl)-2,2′-dihydroxy-1,1′-dinaphthyl (H2(Trip2BINO)) or 3,3′-bis(2,6-diisopropylphenyl)-2,2′-dihydroxy-1,1′-dinaphthyl (H2(Trip2BINO)) in racemic and enantiopure form. The racemic complex [Y(biphen){N(SiHMe2)2}(THF)2] dimerizes upon heating to give the heterochiral complex (R,S)-[Y(biphen){N(SiHMe2)2}(THF)]2. The corresponding dimeric heterochiral lanthanum complex was the sole product in the reaction of H2(Biphen) with [La{N(SiHMe2)2}3(THF)2]. Single-crystal x-ray diffraction of both dimeric complexes revealed that the two Ln(biphen){N(SiHMe2)2}(THF) 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 timescale. All complexes were active catalysts for the hydroamination/cyclization of aminoalkynes and aminoalkenes at elevated temperature, with [Y((R)-dip2bino){N(SiHMe2)2}(THF)2] being the most active one giving enantioselectivities of up to 57% ee. Kinetic resolution of 2-aminohex-5-ene proceeded with this catalyst with 6.4:1 trans selectivity to give 2,5-dimethylpyrrolidine with a krel of 2.6. After reading the article, we found that the author used (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol(cas: 329735-68-4Recommanded Product: (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. 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).Recommanded Product: (R)-3,3′-Di-tert-butyl-5,5′,6,6′-tetramethylbiphenyl-2,2′-diol
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