Benzothiazole Schiff-bases as potential imaging agents for β-amyloid plaques in Alzheimer’s disease
摘要:
A series of benzothiazole Schiff-bases as potential diagnostic imaging agents targeting beta-amyloid (A beta) plaques in Alzheimer's disease (AD) were synthesized and evaluated. When in vitro binding studies using AD homogenate with [I-125] 6-iodo-2-(4'-dimethyl- amino)-phenyl-imidazo[1,2-alpha]pyridine ([I-125]IMPY) as the reference ligand were carried out with the derivatives, the compounds showed high to low binding affinities for AD homogenate at the K (i) values ranged from 4.38 to 514.65 nM, depending on the substitution on the phenyl ring. Fluorescent staining in vitro showed that one compound with a N,N-dimethylamino group intensely stained A beta plaques within brain sections of postmortem AD patients. The results strongly suggest that these derivatives are worthy of further study and may be a useful amyloid imaging agents for early detection of amyloid plaques in the brain of AD.
Asymmetric Synthesis of α-Amino Phosphonates by Using Cinchona Alkaloid-Based Chiral Phase Transfer Catalyst
作者:Weihua Li、Yifeng Wang、Danqian Xu
DOI:10.1002/ejoc.201801013
日期:2018.10.24
imines catalyzed by a cinchona alkaloid‐based chiralphase‐transfercatalyst has been developed. The process affords the desired hydrophosphonylation of imine products with quaternary stereocenters in good to high yields (up to 95 % yield) and excellent enantioselectivities (up to 99 % ee). And this straightforward protocol can be applied to gram scale reaction effectively.
A highly efficient catalyticenantioselective [4+2] cycloaddition was developed between 2-benzothiazolimines and enecarbamates. A wide range of benzothiazolopyrimidines bearing three contiguous stereogenic centers was obtained in high to excellent yields and with excellent diastereo- and enantioselectivities (d.r. > 98 : 2 and up to >99% ee). Furthermore, this chiral phosphoric acid-catalyzed strategy