Side‐Arm Effect of a Methyl α‐d‐Glucopyranoside Based Lariat Ether Catalysts in Asymmetric Syntheses. Issue 1 (9th September 2014) - Rapi, Zsolt
ABSTRACT Methyl α‐d‐glucopyranoside based monoaza‐15‐crown‐5 type lariat ethers with different heteroatom‐containing side arm attached to the nitrogen of the macrocyclic ring have been synthesized. These compounds were used as chiral phase transfer catalysts in a few asymmetric reactions, such as Michael additions, Darzens condensation, and epoxidation of chalcone. The side arms of the macrocycles had a significant impact on the chemical yields and the enantioselectivity. The effect of the lariat ethers with side arms having heteroatom (O, N, and S) was compared with the effect of the analogues having substituents without a heteroatom. The terminal allyl group also generated a significant enantioselectivity (79% enantiomeric excess) in one of the Michael additions. The application of crown ethers with substituents (CH2)3OH or (CH2)3OCH3 leads to the best enantioselectivities 85% and 99%, respectively.