作者:Rakeshwar B. Chhor、Bernd Nosse、Sebastian Sörgel、Claudius Böhm、Michael Seitz、Oliver Reiser
DOI:10.1002/chem.200390019
日期:2003.1.3
development of a new method for the enantioselective synthesis of disubstituted gamma-butyrolactones is reported. Based on this strategy, the totalsynthesis of three paraconic acids, that is (-)-roccellaricacid, (-)-nephrosteranicacid and (-)-protopraesorediosic acid, and the formal totalsynthesis of (-)-methylenolactocin and (-)-protolichesterinic acid is described, which are important because of their
Continuous flow asymmetric cyclopropanation reactions using Cu(<scp>i</scp>) complexes of Pc-L* ligands supported on silica as catalysts with carbon dioxide as a carrier
作者:Brunilde Castano、Emma Gallo、David J. Cole-Hamilton、Vladimiro Dal Santo、Rinaldo Psaro、Alessandro Caselli
DOI:10.1039/c4gc00119b
日期:——
Continuous flow heterogeneous asymmetric cyclopropanations catalysed by supported hydrogen-bonded (SHB) chiral copper(I) complexes of pyridine containing tetraazamacrocyclic ligands Pc-L* using CO2 as a transport vector are described. The catalytic system showed high stability and good recyclability without loss of activity for at least 24 h in CO2 and catalyst turnover numbers up to 440 were obtained
A strategy towards the stereoselectivesynthesis of bi-and tricyclic sesquiterpene lactones is reported. As key step radical cyclizations of appropriately functionalized trans-4,5-disubstituted γ-butyrolactones, which arereadily available from methyl 2-furoate, were carried out to give rise to 5,6-, 5,7- and 5,7,5-ring systems in diastereo- and enantiomerically pure form.