Total Synthesis of Tipranavir Based on Iridium-Catalyzed Asymmetric Allylic Substitution of Dihydropyranone.

An efficient and highly enantioselective synthesis of tipranavir is realized based on an iridium-catalyzed asymmetric allylic substitution. High yield and diastereoselectivity (>20:1), as well as excellent enantioselectivity (99% ), were obtained for the key intermediate through direct asymmetric alkylation reaction of dihydropyranone with allylic -butyl carbonate. Anti-AIDS drug of tipranavir was finally accomplished in 8 steps and 6 pots starting from commercially available 1-phenyl-3-hexanone in 20.

Effect of Permeable Crystalline Materials on the Mechanical and Porosity Property of Recycled Aggregate and Recycled Aggregate Concrete.

This study investigates the potential of permeable crystalline materials to improve the properties of recycled aggregates and recycled aggregate concrete (RAC). The use of recycled aggregates in concrete production has gained increasing attention due to environmental and economic benefits. However, the lower quality and poorer durability of recycled aggregates limit their wider application.

Invasive Rosa rugosa populations outperform native populations, but some populations have greater invasive potential than others.

Increased performance of invasive plant species in their introduced range vs. their native range has been previously documented. However, performance differences among invasive populations have rarely been explored, despite this information being central to understanding the evolution of invasiveness as well as being a useful basis to inform management of invasive species.