1026003-01-9Relevant articles and documents
Optional site selectivity in the metalation of o- and p-anisidine through matching of reagents with neighboring groups
Maggi, Raimondo,Schlosser, Manfred
, p. 5430 - 5434 (1996)
N-Protected o- and p-anisidines (2- and 4-methoxyanilines) undergo a hydrogen/metal exchange at the position adjacent to either the oxygen or nitrogen atom depending on what organometalic base is employed. These synthetically useful findings support previous views about neighboring group/reagent interactions.
Toolbox approach to the search for effective ligands for catalytic asymmetric Cr-mediated coupling reactions
Guo, Haibing,Dong, Cheng-Guo,Kim, Dae-Shik,Urabe, Daisuke,Wang, Jiashi,Kim, Joseph T.,Liu, Xiang,Sasaki, Takeo,Kishi, Yoshito
supporting information; experimental part, p. 15387 - 15393 (2010/02/15)
Chromium catalysts derived from chiral sulfonamides represented by A effect the couplings of aldehydes with vinyl, allyl, or alkyl halides. With three distinct sites for structural modification, A affords access to a structurally diverse pool of chiral sulfonamides. The Cr catalysts derived from these sulfonamides exhibit a broad range of catalyst-substrate matching profiles. A strategy is presented to search for a satisfactory chiral sulfonamide for a given substrate. In order to demonstrate the generality and effectiveness of this approach, five diverse C-C bond-forming cases have been selected from the halichondrin synthesis. For each of the cases, two ligands have been deliberately searched for, to induce the formation of (R)- and (S)-alcohols, respectively, at the arbitrarily chosen efficiency level of "≥80% yield with ≥20:1 stereoselectivity in the presence of ≤20 mol % of a Cr catalyst". For 9 out of the 10 cases studied, a satisfactory catalyst has been found within this pool of sulfonamides. Even for the remaining case, a Cr catalyst inducing stereoselectivity up to 8:1 has been identified.
