Self-association free bifunctional thiourea organocatalysts: synthesis of chiral α-amino acids via dynamic kinetic resolution of racemic azlactones
作者:Joong-Suk Oh、Ji-Woong Lee、Tae Hee Ryu、Jae Heon Lee、Choong Eui Song
DOI:10.1039/c1ob06629c
日期:——
Concentration-independent high enantioselectivity in the dynamickineticresolution (DKR) of racemic azlactones affording chiral α-aminoesters has been achieved using self-association free thiourea-based dimeric cinchona alkaloid organocatalysts. Detailed experimental studies and single crystal X-ray analysis confirmed that these bifunctionalorganocatalysts I do not form H-bonded self-aggregates in either
Organocatalytic asymmetric [4+2] cyclization of 2-benzothiazolimines with azlactones: access to chiral benzothiazolopyrimidine derivatives
作者:Qijian Ni、Xuyang Wang、Fangfang Xu、Xiaoyun Chen、Xiaoxiao Song
DOI:10.1039/d0cc00736f
日期:——
An organocatalytic asymmetricdomino Mannich/cyclization reaction between 2-benzothiazolimines with azlactones has been successfully developed. With the bifunctional squaramide catalyst, this formal [4+2] cyclization occurs with good to high yields and excellent stereoselectivities (up to 99% ee, >20 : 1 dr), providing an efficient and mild access to chiral benzothiazolopyrimidines bearing adjacent