Lin-Li Wei

A Novel and Highly Stereoselective Intramolecular Formal [3+3] Cycloaddition Reaction of Vinylogous Amides Tethered withα,β-Unsaturated Aldehydes: A Formal Total Synthesis of (+)-Gephyrotoxin

Complex piperidinyl heterocycles (for example, 2) were accessed by using a novel intramolecular formal [3+3] cycloaddition reaction of vinylogous amides tethered with enals (for example, 1). This method has been applied to a formal total synthesis of (+)-gephyrotoxin (3).

The total synthesis of (′)-arisugacin A

Abstract A 20-step total synthesis of (±)-arisugacin A with an overall yield of 2.1% is described here in detail. This synthesis features a formal [3+3] cycloaddition reaction of α,β-unsaturated iminium salts with 6-aryl-4-hydroxy-2-pyrones through a highly stereoselective 6π-electron electrocyclic ring-closure of 1-oxatriene. A strategic dihydroxylation–deoxygenation protocol leading to the desired angular C12a–OH was developed to serve as a critical step in leading to the final total syntheses of arisugacin A. This synthetic endeavor also led to an interesting and unexpected retro-aldol–aldol sequence in the AB-ring.

Synthesis of dihydroxanthone derivatives and evaluation of their inhibitory activity against acetylcholinesterase: unique structural analogs of tacrine based on the BCD-ring of arisugacin.

A general approach to synthesis of dihydroxanthone derivatives is described here. In vitro evaluation of these dihydroxanthones demonstrated that some derivatives possess moderate anti-cholinesterase activities and better selectivities than tacrine for acetylcholinesterase over butyrylcholinesterase. Structural effects on anti-cholinesterase activities were also examined, and docking experiments were carried out to provide preliminary understandings of these experimental observations.

An unexpected retro-aldol–aldol in the AB-ring in the synthesis of (±)-arisugacin A

Abstract Endeavors including an unexpected retro-aldol–aldol process that proved to be critical for our eventual total synthesis of arisugacin A are described here.