Total syntheses of variolin B and deoxyvariolin B.

Two alternative synthetic routes have been developed for the preparation of variolin B and deoxyvariolin B. The strategy is based on the preparation of the core tricyclic ring common to all variolins, pyrido[3',2':4,5]pyrrolo[1,2-c]pyrimidine, followed by a palladium-catalyzed cross-coupling reaction to give the tetracyclic system.

A general method for convergent synthesis of functionalized exo-glycals based on halogenation and Suzuki cross-coupling of 1-exo-methylene sugars.

Functionalized exo-glycals can be readily obtained by palladium catalyzed Suzuki cross-coupling of halo-exo-glycals with boronic acids.