Chiral phosphoric acid-catalyzed asymmetric epoxidation of alkenyl aza-heteroarenes using hydrogen peroxide.

The synthesis of chiral α-azaheteroaryl oxiranes via enantioselective catalysis is a formidable challenge due to the required complex stereoselectivity and diverse N-heterocyclic structures. These compounds play a crucial role in developing bioactive molecules, where precise chirality significantly influences biological activity. Here we show that using chiral phosphoric acid as a catalyst, our method efficiently addresses these challenges. This technique not only achieves high enantio- and diastereoselectivity but also demonstrates superior chemo- and stereocontrol during the epoxidation of alkenyl aza-heteroarenes. Our approach leverages a synergistic blend of electrostatic and hydrogen-bonding interactions, enabling the effective activation of both substrates and hydrogen peroxide. The resulting chiral oxiranes exhibit enhanced diversity and functionality, aiding the construction of complex chiral azaaryl compounds with contiguous stereocenters. Kinetic and density functional theory studies elucidate the mechanism, highlighting chiral phosphoric acid's pivotal role in this intricate enantioselective process.

Research progress of new oral anticoagulants in nonvalvular atrial fibrillation / 心血管康复医学杂志

Oral anticoagulants has become the cornerstone preventing thromboembolic complications in patients with atrial fibrillation (AF ) who are at high risk for stroke .Advantages of new oral anticoagulants (NOAC ) include greater pharmacokinetic predictability ,less risk of fatal or intracranial hemorrhage compared to vitamin K antago-nists ,fewer drug-food interactions and no long time monitoring of international standardized ratios etc .The present article focused on recent studies of NOAC in AF complicated coronary diseases ,for secondary prevention of stroke and its specific antagonists .

Isolation and antifungal activities of a pair of isomers of phloroglucinol derivatives from Dryopteris fragrans / 中草药

Objective: To study the chemical constituents and antifungal activitiy of phloroglucinol derivatives from Dryopteris fragrans. Methods: The phloroglucinol derivatives were isolated by silica gel column chromatography, Sephadex LH-20 column chromatography, and pre-HPLC. The chemical structures were elucidated on the basis of physicochemical and spectral properties. The antifungal activities against Trichophyton rubrum and Microsporum gypseum were tested by CLSI M38-A2 broth microdilution methods. Results: Two phloroglucinol derivatives were isolated and identified as disflavaspidic acid PB (1) and flavaspidic acid PB (2). The minimum inhibitory concentration (MIC) of compounds 1 and 2 were 13.33 and 1.875 μg/mL against T. rubrum respectively, 10 and 1.325 μg/mL against M. gypseum. Conclusion: Compound 1 is a new compound named disflavaspidic acid PB. Compound 2 is isolated from D. fragrans for the first time. Compounds 1 and 2 are a pair of isomers with promising antifungal activity.