Preparation of a Bicyclic Analog of Qinghao (Artemisinic) Acid via a Lewis Acid Catalyzed Ionic Diels-Alder Reaction Involving a Hydroxy Diene and Cyclic Enone and Facile Conversion into (.+-.)-6,9-Desdimethylqinghaosu

Bouncing off walls - widths of exit channels from shallow minima can dominate selectivity control

A selectivity model based on the widths of pathways to competing products, rather than barrier heights, is formulated for the butadiene + allyl cation reaction. This model was arrived at via analysis of stationary points, intrinsic reaction coordinates, potential energy surface shapes and direct dynamics trajectories, all determined using quantum chemical methods.

Synthesis of Benzothiophene-Fused Oxa[6.6.5]tricyclic Skeletons through a Cinchonidine- or NaOH-Promoted Quadruple Domino Sequence

Two base-promoted quadruple domino reactions between thioaurones and allylic phosphonium salts have been developed to synthesize benzothiophene-fused oxa[6.6.5]tricyclic skeletons in moderate to good yields with excellent stereoselectivity and broad functional-group tolerance. This is a simple and useful protocol for the rapid construction of the umbrella-like oxa[6.6.5]tricyclic skeleton.

Convenient Access Both to Highly Antimalaria-Active 10-Arylaminoartemisinins, and to 10-Alkyl Ethers Including Artemether, Arteether, and Artelinate

An economical phase-transfer method is used to prepare 10-arylaminoartemisinins from DHA and arylamines, and artemether, arteether, and artelinate from the corresponding alcohols. In vivo sc screens against Plasmodium berghei and P. yoelii in mice reveal that the p-fluorophenylamino derivative 5 g is some 13 and 70 times, respectively, more active than artesunate; this reflects the very high sc activity of 10-alkylaminoartemisinins. However, through the po route, the compounds are less active than the alkylaminoartemisinins, but still approximately equipotent with artesunate.