Highly Enantioselective Decarboxylative Protonation of α-Aminomalonates Mediated by Thiourea <i>Cinchona</i> Alkaloid Derivatives: Access to Both Enantiomers of Cyclic and Acyclic α-Aminoacids
Thiourea derived cinchona alkaloids promote the asymmetric decarboxylative protonation of cyclic, acyclic, or bicyclic alpha-aminomalonate hemiesters under mild and metal-free conditions to afford enantioenriched aminoesters in high yields and enantioselectivities up to 93%. Both enantiomers of the aminoesters have been synthesized with the same selectivity when using organic base 3 and its pseudoenantiomer
Ultrasound-Promoted Enantioselective Decarboxylative Protonation of α-Aminomalonate Hemiesters by Chiral Squaramides: A Practical Approach to Both Enantiomers of α-Amino Esters
作者:Surajit Some、Han Yong Bae Mun Jong Kim、Yong Jian Zhang、Choong Eui Song
DOI:10.1002/ejoc.201700786
日期:2017.8.24
Ultrasound-promoted enantioselective decarboxylative protonation reaction of α-aminomalonate hemiesters in the presence of chiral cinchona-derived squaramide Brønsted bases under mild conditions afforded both the (S)- and (R)-enantiomers of α-amino acid derivatives in excellent yields (> 90 %) and excellent enantioselectivities (up to 98 % ee).