Abstract: Terpenoid natural products host a range of potentially valuable biological activities. However, congeners with high degrees of oxidation and steric encumbrance are challenging to prepare by canonical chemical transformations. This problem inspired us to develop a novel annulation capitalizing on metal hydride hydrogen atom transfer (MHAT) chemistry. We leveraged this new annulation in a concise synthesis of a labdane diterpenoid, forskolin and a quassinoid natural product, quassin.