Total Syntheses of Seven Stemoamide-Type Stemona Alkaloids

Six Stemona alkaloids were synthesized racemically by using stemoamide, obtained via cascade cyclization or our reported transannular cyclization of parvistemoamide, as the common intermediate. Thioamides facilitated the separation of isosaxorumamide...

Ring-Closing Metathesis Approach to Cage Propellanes Containing Oxepane and Tetrahydrofuran Hybrid System

The preparation of a variety of structurally interesting oxygenated cage compounds involving atom-economic processes such as Claisen rearrangement, Diels–Alder reaction, [2+2] photocycloaddition, and ring-closing metathesis (RCM) as key steps is reported. For the first time, oxepane ring system is introduced in cage framework using olefin metathesis as a key step. These cage systems assembled here are difficult to prepare by traditional methods. The synthetic sequence described here opens up new routes to higher order polycycles containing heteroatoms without the involvement of protecting groups. Transannular cyclization observed during Grignard addition and the RCM protocol used here may be applicable to generate unknown oxygenated cage systems.

Total synthesis of (±)-20S-hydroxy-1,2-dehydro-pseudoaspidospermidine via a C–H activation/transannular cyclization strategy

A total synthesis to the pseudoaspidospermidine family via a C–H activation/transannular cyclization strategy has been accomplished.