Assembly of (2xC₂+C'₂)xn Molecular Complexity Using a Sequence of Pt- and Pd-Catalyzed Transformations with Calcium Carbide

Constructing molecular complexity from simple precursors stands as a cornerstone in contemporary organic synthesis. Systems harnessing easily accessible starting materials, which offer control over stereochemistry and support a modular assembly approach, are particularly in demand. In this research, we utilized calcium carbide, presenting a sustainable pathway to generate acetylene gas - a fundamental C-2 building block. We performed a Pt-facilitated linkage of two C-2-units sourced from two calcium carbide molecules to craft a conjugated C-4 core with exceptional stereoselectivity. As a benchmark, we selected the synthesis of (E,E)-1,4-diiodobuta-1,3-diene, executing it in a two-chamber reactor. Compartmentalization of the reactions across these chambers resulted in the desired product in 85% yield. Furthermore, high-energy polymeric substances were derived by marrying the molecular intricacy between (E,E)-1,4-diiodobuta-1,3-diene and calcium carbide, underpinning a unique C-4+C-2 assembly blueprint. The structure and morphology of the polymeric material were characterized by IR and NMR spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Overall, two complementary 2xC(2)-to-C-4 and (2xC(2)+C'(2))xn assembly schemes were developed using Pt and Pd catalysis.