Facile enantioselective synthesis of multi-substituted norbornanes/norbornenes using a latent synthon strategy

The development of a new catalytic asymmetric synthetic methodology has been following virtually the same pattern in the past decades. Herein, we present a latent synthon strategy within this well-established research domain. By employing substrates containing latent groups, specifically “ON-alkene” in this investigation, a single optimization exercise yields the Diels–Alder adduct with excellent enantiomeric purity. This adduct serves as a universal intermediate, undergoing late-stage diversifications via robust and easily performed synthetic transformations. Consequently, a broad array of structurally diverse chiral norbornanes (NBAs) and norbornenes (NBEs) are obtained with consistent and high enantiomeric purities. Furthermore, our methodology allows for facile asymmetric preparation of chiral NBE ligands as well as the concise synthesis of (+)-gemmacin, ( + )-gemmacin B, and their structural analogs.