Synthesis of Functionalized 2,3- and 3,4-Dihydropyrans Starting from α-Hydroxycarboxylic Esters <i>via</i> RCM
作者:Bernd Schmidt、Holger Wildemann
DOI:10.1055/s-1999-2884
日期:——
α-Hydroxy carboxylic acids and their derivatives are naturally occurring starting materials for the synthesis of functionalized tetrahydropyrans using ring closing metathesis and base induced epoxide rearrangement as key steps. (S)-Lactic acid methyl ester has been used as the starting material for the preparation of enantiomerically pure 6-desoxy C-glycoside precursors.
Ferrier/Aza‐Wacker/Epoxidation/Glycosylation (FAWEG) Sequence to Access 1,2‐
<i>Trans</i>
3‐Amino‐3‐deoxyglycosides
作者:Anselme Geulin、Yann Bourne‐Branchu、Kawther Ben Ayed、Thomas Lecourt、Antoine Joosten
DOI:10.1002/chem.202203987
日期:2023.3.22
Travelling without moving: A Ferrier rearrangement/aza-Wacker cyclization on commercial glycals allows both a 3,4-cis amination at position three and a motion of the double bound restoring the glycal. Epoxidation/glycosylation of N-Ts 3-amino-3-deoxygalactal provided disaccharide with high diastereoselectivity and yield, thus defining FAWEG (Ferrier/Aza-Wacker/Epoxidation/Glycosylation) as a new sequence
<i>pseudo</i>Enantiomeric Carbohydrate Olefin Ligands - Case Study and Application in Kinetic Resolution in Rhodium(I)-Catalysed 1,4-Addition
作者:Holger Grugel、Fabian Albrecht、Mike M. K. Boysen
DOI:10.1002/adsc.201400459
日期:2014.11.3
AbstractIn order to investigate significant differences in asymmetric induction for pseudo enantiomeric carbohydrate olefin ligands in rhodium(I)‐catalysed 1,4‐addition reactions, we designed a set of new olefin ligands differing in relative configuration and pyranoside conformation. With these, we have successfully elucidated structural requirements for metal binding and also identified an improved alternative for one pseudo enantiomer. Furthermore, we report the efficient kinetic resolution of a racemic 4‐hydroxycyclopentenone derivative by 1,4‐addition.magnified image