Enantioselective Total Synthesis of Lycoposerramine-Z Using Chiral Phosphoric Acid Catalyzed Intramolecular Michael Addition.

A new enantioselective total synthesis of phlegmarine-type Lycopodium alkaloid lycoposerramine-Z (1) has been accomplished, using one-pot chemoselective sequential additions of two different Grignard reagents to the bis-Weinreb-amide intermediate and an efficient construction of the fully fuctionalized cyclohexanone intermediate with a chiral phosphoric acid catalyzed enantioselective intramolecular Michael addition.

Total syntheses of lycoposerramine-V and 5-epi-lycoposerramine-V.

Enantioselective total syntheses of lycopodium alkaloids lycoposerramine-V and 5-epi-lycoposerramine-V have been accomplished. Features of the newly established total synthesis include: 1) introduction of the first chiral center with a scalable desymmetrization reaction of an meso-anhydride; 2) chemoselective functionalization of a bis-Weinreb-amide with Grignard addition; and 3) construction of the multifunctionalized cyclohexanone with a stereoselective intramolecular Michael addition.

Protecting group-free total synthesis of (-)-lannotinidine B.

The first total synthesis of (-)-lannotinidine B, a unique tetracyclic constitutent of Lycopodium annotinum, has been accomplished in 10 steps with 23% overall yield. The completed short and efficient synthesis is characterized with three highly chemo- and/or stereoselective reductive-amination steps to furnish the desired trans-fused 6/6 bicycle and the aza seven-membered ring system, and a direct intramolecular acyloin condensation to deliver the cyclopentanone moiety, as well as successful application of a protecting group-free strategy and an optimal redox order.