62618-74-0Relevant academic research and scientific papers
Catalytic scaffolding ligands: An efficient strategy for directing reactions
Lightburn, Thomas E.,Dombrowski, Michael T.,Tan, Kian L.
supporting information; experimental part, p. 9210 - 9211 (2009/02/03)
The design and application of a scaffolding ligand that promotes branch and diastereoselective hydroformylation of terminal olefins as well as the regio- and diastereoselective hydroformylation of disubstituted olefins is reported. It is shown that the ligand covalently and reversibly bonds to the substrate, allowing for directed hydroformylation. As the substrate ligand interaction is dynamic, hydroformylations are catalytic in ligand and do not require any additional synthetic steps to add or remove the directing group. Using a catalytic quantity of a scaffolding ligand (20-25 mol %), excellent regioselectivity for disubstituted olefins (up to 98:2) and high branch selectivity (up to 88:12) for terminal olefins were obtained. Copyright
HIGHLY REGIOSELECTIVE RING-OPENING OF α-SUBSTITUTED CYCLIC ACID ANHYDRIDES CATALYZED BY LIPASE
Hiratake, Jun,Yamamoto, Kazuyoshi,Yamamoto, Yukio,Oda, Jun'ichi
, p. 1555 - 1556 (2007/10/02)
Lipase Amano P irreversibly catalyzed a ring-opening of α-substituted cyclic acid anhydrides 1 preferentially at the less hindered carbonyl group to give monoesters with high regioselectivity.
Quantitative Correlation between Calculated Molecular Properties and Retention of a Series of Structurally Related Racemates on Cellulose Triacetate
Wolf, Romain M.,Francotte, Eric,Lohmann, Dieter
, p. 893 - 902 (2007/10/02)
Racemic compounds cionsisting of an alicyclic six-membered ring with a phenyl group attached to the chiral carbon atom have been investigated.The chemical structure of the alicyclic part was varied systematically, in order to establish its influence on the separability of the racemates into their pure enantiomers on cellulose triacetate (CTA).Theoretical investigations, involving conformational analysis and charge distribution, have been undertaken to correlate structural features with chromatographic behaviour.For this class of compounds two major parameters governing the interaction with CTA are the rotational freedom of the bond to the phenyl group and thereby the relative ability to assume the flattest possible conformation, and a negatively charged neighbourhood of the chiral centre.
Ruthenium Complex Catalyzed Regioselective Dehydrogenation of Unsymmetrical α,ω-Diols
Ishii, Youichi,Osakada, Kohtaro,Ikariya, Takao,Saburi, Masahiko,Yoshikawa, Sadao
, p. 2034 - 2039 (2007/10/02)
Ruthenium complex catalyzed regioselective dehydrogenation of unsymmetrically substituted 1,4- and 1,5-diols in the presence of such a hydrogen acceptor as α,β-unsaturated ketone gave predominantly β-substituted γ-lactones and γ-substituted δ-lactones, respectively.Among the ruthenium complexes, RuH2(PPh3)4 was the most active and selective catalyst and showed high catalytic activity even at 20 deg C.For example, 2,2-dimethyl-1,4-butanediol was quantitatively converted to dihydro-4,4-dimethyl-2(3H)-furanone and dihydro-3,3-dimethyl-2(3H)-furanone in a ratio of 99.6/0.4 in the presence of 4-phenyl-3-buten-2-one (hydrogen acceptor) and a catalytic amount of RuH2(PPh3)4 at 20 deg C.The proposed main factor controlling the regioselectivity is the steric constraints produced by the substituent(s) of a diol at the coordination step of alkoxy group to ruthenium.
