Retrosynthetic strategies to forge such entities are still plagued with a non-intuitive logic where building blocks used do not clearly map onto the product into which they are ultimately incorporated. Specifically, these approaches are non-modular and individually target each poly-olefin synthesized. Furthermore, they often lack complete control of olefin geometry (a critical feature controlling the resulting sp 3 stereochemistry), and require multiple functional group interconversions (FGIs). The current barrier to rapid, modular, and controlled polyene construction therefore limits the effectiveness of what is arguably one of the most powerful complexity-inducing chemical transformations known. Meanwhile, steady advancement in the development of methodology for creating sp -sp linkages has pointed towards a simpler approach to polyene synthesis (Figure ). The cyclase phase of natural terpene assembly points to inherent advantages of a modular approach as a simple building block like isopentenyl pyrophosphate (IPP) can be intuitively mapped onto the final polyene product. The goal of this study was to mimic this strategy for modular terpene synthesis by focusing on disconnecting sp 2 -sp 3 bonds directly to arrive at simple carboxylic acid precursors (Figure ). By combining the learnings of decarboxylative C-C bond formation and electrochemical cross-electrophile coupling with a new application of in situ electrode functionalization we show how halo-acid modules can be iteratively coupled resulting in more logical retrosynthetic analyses that reduce step-counts, reliance on pyrophoric reagents, and remove non-ideal manipulations. The scalable access to 13 terpene natural products exemplifies the strategic power of this logic. Furthermore, the mechanistic interplay between the Fig. . The synthesis of polyene cyclization precursors remains a challenge to chemists. Taking inspiration from chemical and natural precedent, this work developed a modular platform constructing sp -sp bonds utilizing an electrochemical reaction and functionalized electrodes. (A) Retrosynthetic analysis of Johnson's classic total synthesis of progesterone. (B) The advantages of a prototypical sp 2 -sp disconnection and the biosynthesis of geraniol pyrophosphate. Adenosine triphosphate (ATP) activation of an alcohol generates the reactive chemical feedstocks necessary for terpene synthesis. (C) Combining the advantages of the sp 2 -sp 3 disconnection and nature's modular and selective activation strategy required development of a mild reaction using nickel electrocatalysis and Ag-nanoparticle functionalized electrodes.