newly formed stereocenters. When iron-catalyzed borrowing hydrogen from allylic alcohols was combined with a stereocontrolled organocatalytic oxa-Michael addition, a wide array of chiral tetrahydropyrans were efficiently prepared. The reaction could be performed in a diastereoselective manner from pre-existing stereocenters or enantioselectively from achiral substrates. The key to success was the reactivity
Asymmetric Dehydrative Cyclization of ω-Hydroxy Allyl Alcohols Catalyzed by Ruthenium Complexes
作者:Shinji Tanaka、Tomoaki Seki、Masato Kitamura
DOI:10.1002/anie.200904671
日期:2009.11.9
New axially chiral ligands and their allyl esters have been designed and synthesized. The combination of these ligands with [CpRu(CH3CN)3]PF6 has realized highly efficient intramolecular dehydrative cylization of ω‐hydroxy allylalcohols, to give α‐alkenyl‐substituted cyclic ethers with up to greater than 99:1 enantiomeric ratio without activation of the allylic moieties (see scheme; Cp=cyclopentadienyl