Recent Advances in Ent-Abietane Diterpenes: Natural Sources, Biological Activities and Total Synthesis

<i>Ent</i>-abietane diterpenoids constitute a class of terpenes with a C₂₀ carbon skeleton that underlie a wide range of biological activities. <i>Ent</i>-abietane diterpenoids, enantiomeric to the abietane counterparts, represent a family of diterpenoid natural products characterized by their distinct 6/6/6 tricyclic carbocyclic skeletons with exceptional structural complexity. An increasing number of these <i>ent</i>-abietane diterpenoids have recently been identified, constituting a well-defined group of naturally occurring compounds. This review provides a comprehensive summary of the natural sources, chemical structures, biological profiles and total synthesis of these <i>ent</i>-abietane diterpenoids from 2016 to early 2025.